ASME Conference Presenter Attendance Policy and Archival Proceedings

2017;():V001T00A001. doi:10.1115/MSEC2017-NS1.

This online compilation of papers from the ASME 2017 12th International Manufacturing Science and Engineering Conference (MSEC2017) represents the archival version of the Conference Proceedings. According to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference by an author of the paper, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.

Commentary by Dr. Valentin Fuster

Processes: Advances and Challenges in Joining and Assembly Processes

2017;():V001T02A001. doi:10.1115/MSEC2017-2605.

Friction stir welding (FSW) is a solid state welding process used for welding similar and dissimilar materials. The process is widely used because it does not have common problems such as solidification and liquefaction cracking associated with the fusion welding techniques. The objective of the present research is to find the best combination of friction stir welding process parameters to join aluminium 5052 and 6061 alloy materials. The combination of process parameters is helpful to improve ultimate tensile strength, yield strength, percentage of elongation and hardness of welded joint. To achieve the research objective taguchi based grey analysis was used. The optimum process parameters were found be at rotational speed is 1400 rpm, transverse speed of 100 mm/min and axial force is at 11 KN.

Commentary by Dr. Valentin Fuster
2017;():V001T02A002. doi:10.1115/MSEC2017-2692.

Non-Destructive Evaluation (NDE) of welded structures is essential in industry and manufacturing sectors. However, NDE techniques are limited when applied at high temperatures, which prevents usefulness for on-line real time inspection of welded joints. In this work, a high temperature (HT) inspection system was created utilizing Phased Array Ultrasonic Testing (PAUT), and tested on Friction Stir (FS) welded aluminum alloy joints. The system created in this work proves HT-PAUT is capable of determining defects during the welding process. Supplementing this work, a custom defect detection software was created to analyze S-Scan data to interpret when and where a defect occurs to provide defect indicator signals. These defect signals can be utilized for controlling the FSW process parameters to automatically correct if a defect is observed. The technology developed can be utilized as a platform for future automated welding processes and control for creating the next generation weld-NDE systems.

Commentary by Dr. Valentin Fuster
2017;():V001T02A003. doi:10.1115/MSEC2017-2700.

This study presents a detailed analysis of friction stir riveting (FSR) processes that are used for joining similar as well as dissimilar materials. It covers the operating principle of FSR methods along with the insight into various process parameters responsible for successful joints formation. The paper further evaluates the research in friction stir-based riveting processes which unearth the enhanced metallurgical and mechanical properties for instance microstructure modification, local mechanical properties and improved strength, corrosion and fatigue resistance. The results of the study show that use of FSR process yields refined microstructures and improved mechanical properties in materials, which will entail a significant rise in the usage of friction stir-based riveting processes.

Topics: Friction , Riveting
Commentary by Dr. Valentin Fuster
2017;():V001T02A004. doi:10.1115/MSEC2017-2786.

The requirement of increased fuel economy standards has forced automakers to incorporate multi-materials into their current steel dominant vehicles in order to lightweight their fleets. Technologies such as Self Piercing Rivets and Flow Drill Screws are currently implemented for joining aluminum to high-strength steels but only one-technology is viable for joining aluminum to ultra-high-strength steels without pre-holes, namely Friction Element Welding. This study is aimed at investigating how variations in the cleaning and welding steps of the Friction Element Welding process influence joint quality. A design of experiment was conducted to understand the influence of key process parameters (endload, spindle RPM, and relative distance) during these steps on the pre-defined joint quality metrics of head height, weld zone diameter, under-head fill area, temperature, and microhardness. It is found that cleaning step parameters have the greatest influence on process time and energy consumption, while welding step parameters greatly influence maximum torque on the element, head height, and underhead fill, with both cleaning force and weld force influencing weld diameter, all parameters influence temperature.

Topics: Friction , Welding
Commentary by Dr. Valentin Fuster
2017;():V001T02A005. doi:10.1115/MSEC2017-2803.

This paper studies an electrically assisted friction stir spot welding (FSSW) process for joining aluminum alloy 6061-T6 to TRIP 780 steel. The electrical current shows to reduce the axial plunge force and assist the material flow of the aluminum matrix during the welding process. When electrical pulses and direct current (DC) with the same energy input are applied, the results show insignificant differences. Bulk material flow can be observed in the weld cross sections. A more uniform hook is generated at the Fe/Al interface after applying the current. Besides, the diffusion of aluminum atoms into the steel matrix is enhanced. Regarding the weld quality, electrically assisted FSSW improves the joint lap shear strength when compared with regular FSSW process.

Commentary by Dr. Valentin Fuster
2017;():V001T02A006. doi:10.1115/MSEC2017-3019.

Friction stir forming utilizes a friction stirring action to soften and extrude a base material into a cavity in a substrate material thereby forming a joint. In this research, Abaqus software was used to model the process in order to understand the key joint features of interest and provide direction for experimental optimization. A three dimensional, thermo-mechanical finite element model was developed and applied to simulate the process and obtain detailed stress and temperature distribution plots. Adaptive mesh and contact features were utilized for large deformation of the aluminum work material. It was found that the model accurately predicted the shape of the joint and flash extrusion during the process. The maximum temperature was found at the outer radius of the tool, but was much lower than temperatures in friction stir welding.

Commentary by Dr. Valentin Fuster
2017;():V001T02A007. doi:10.1115/MSEC2017-3034.

Friction stir blind riveting (FSBR) is a novel and highly efficient joining technique for lightweight metal materials, such as aluminum alloys. The FSBR process induced large gradients of plastic deformation near the rivet hole surface and resulted in a distinctive gradient microstructure in this domain. In this study, microstructural analysis is conducted to analyze the final microstructure after the FSBR process. Dynamic recrystallization (DRX) is determined as the dominant microstructure evolution mechanism due to the significant heat generation during the process. To better understand the FSBR process, a two-dimensional Cellular Automaton (CA) model is developed to simulate the microstructure evolution near the rivet hole surface by considering the FSBR process loading condition. To model the significant microstructure change near the rivet hole surface, spatial distributed temporal thermal and mechanical loading conditions are applied to simulate the effect of the large gradient plastic deformation near the hole surface. The distribution grain topography and recrystallization fraction are obtained through the simulations, which agree well with the experimental data. This study presents a reliable numerical approach to model and simulate microstructure evolution governed by DRX under the large plastic deformation gradient in FSBR.

Commentary by Dr. Valentin Fuster
2017;():V001T02A008. doi:10.1115/MSEC2017-3092.

Setting optimum process parameters is very critical in achieving a sound friction stir weld joint. Understanding the formation of defects and developing techniques to minimize them can help in improving the overall weld strength. The most common defects in friction stir welding are tunnel defects, cavities and excess flash formation which are caused due to incorrect tool rotational or advancing speed. In this paper, the formation of these defects is explained with the help of an experimentally verified 3D finite element model. It was observed that the asymmetricity in temperature distribution varies for different types of defects formed during friction stir welding. The location of the defect also changes based on the shoulder induced flow and pin induced flow during friction stir welding. Besides formation of defects like excess flash, cavity defects, tunnel/wormhole defects, two types of groove like defects are also discussed in this paper. By studying the different types of defects formed, a methodology is proposed to recognize these defects and counter them by modifying the process parameters to achieve a sound joint for a displacement based friction stir welding process.

Commentary by Dr. Valentin Fuster

Processes: Advances in Assisted/Augmented Manufacturing Processes

2017;():V001T02A009. doi:10.1115/MSEC2017-2654.

Machining is the manufacturing process, capable of producing required shape and size by material removal. In recent times industries are striving to enhance the performance of machining processes. One of the problem associated with machining is the amount of heat generation as a result of friction between tool and workpiece. Heat generated may affect the quality of machined surface and tool wear. In order to control it, cutting fluid is applied in large quantity. The problem arises with the use of cutting fluid is its effect on worker’s health and environment. The present investigation is an attempt to explore the use the solid lubricants in machining as an alternative to cutting fluid. The work involves development of minimum quantity solid lubrication set up. Turning experiments has been performed by applying solid lubricants mixed with cutting fluid in minimum quantity. The performance of minimum quantity solid lubrication has been assessed in form of obtained surface finish, power consumption and tool wear during turning. Experimental findings discovered the superiority of minimum quantity solid lubrication over conventional cutting fluid and can be considered as cost effective and sustainable lubrication method.

Topics: Lubrication , Turning
Commentary by Dr. Valentin Fuster
2017;():V001T02A010. doi:10.1115/MSEC2017-2691.

Manufacturing of aspheric profile of lens at nanometric level is difficult but the measurement and evaluation of metrology parameters is still a bigger challenge. For successful results of the lens systems, precise and defect free lenses are required. The manufacturing conditions have direct effect on the metrological parameters. For appropriate evaluation of metrology parameters, proper interpretation of aspheric surface parameters must be known. . In this study, the mechanical parameters, such as radius of curvature, slope error, tilt, centre thickness, and sag value of lens, were measured by using contact type form talysurf, non-contact type fizeau interferometers, and other instruments. The experimental results reveal that an increase in the spherical aberration is caused by increasing the lens thickness beyond 4.995mm or by increasing the radius of curvature beyond −13.8396mm or by increasing the aspheric higher order coefficients. Also its dependencies on the diameter of least confusion is studied.

Commentary by Dr. Valentin Fuster
2017;():V001T02A011. doi:10.1115/MSEC2017-2755.

In most trendsetting industries like the aerospace, automotive and medical industry functionally critical parts are of highest importance. Due to strict legal requirements regarding the securing of the functionality of high-risk parts, both production costs and quality costs contribute significantly to the manufacturing costs. Thus, both types of costs have to be taken into consideration during the stage of technology planning. Due to the high variety of potential interactions between individual component properties as well as between component properties and manufacturing processes, the analysis of the influence of the manufacturing history on an efficient design of inspection processes and inspection strategies is extremely complex. Furthermore, the effects of inspection strategies and quality costs on the planning of manufacturing process sequences cannot be modeled to date. As a consequence, manufacturing and inspection processes are designed separately and thus a high cost reduction potential remains untapped.

In this paper a new approach for an integrative technology and inspection planning is presented and applied to a case study in medical industry. At first, existing approaches with regard to technology and inspection planning are reviewed. After a definition of relevant terms the case study is introduced. Following, an approach for an integrative technology and inspection planning is presented and applied to the case study. In the presented approach the complex causalities between technology planning, manufacturing history and inspection planning are considered to enable a cost-effective production process and inspection sequence design.

Commentary by Dr. Valentin Fuster
2017;():V001T02A012. doi:10.1115/MSEC2017-2758.

Rocks are playing an important role in the life of mankind since ancient times. One of the most significant characteristics of the rocks is their brittleness, which makes them exhibit a very poor machinability and usually severe fracture results during machining. In this paper, Micro-Laser Augmented Machining (μ-LAM) technique is applied on scratching a commercial rock, Gabbro-Labradorite, which is a composite of grained natural minerals such as feldspar, magnetite and mica. In the μ-LAM process, a laser is used to locally heat and thermally soften the materials below the scratching tool during the machining operation. In this paper, scratching tests have been done on the Gabbro-Labradorite minerals, with and without laser heating and results are compared and reported. Micro-laser assisted scratch tests (with an actual cutting tool) were successful in demonstrating the enhanced thermal softening of the feldspar and magnetite minerals. The effect of the laser power was studied by measuring the depths of the cuts for the scratch tests. When generating the scratches with a diamond tool, load range was increased from 50 to 500 mN. Laser powers of 10, 15, 20, and 25 Watt (W) have been utilized. All the tests were repeated two times to increase the reliability of the results. 3D profiles were generated by using a white light interferometer and microscopic images of the cuts have been reported. Results show that Ductile to Brittle Transition (DBT) depth, which is the critical depth for machining brittle materials, increased with the aid of the laser. Results are very important for the machining of the Gabbro-Labradorite to get a high material removal rate (MRR), low tool wear and better surface quality.

Topics: Lasers , Machining , Rocks
Commentary by Dr. Valentin Fuster
2017;():V001T02A013. doi:10.1115/MSEC2017-2766.

Increasing governmental fuel economy requirements drives automakers to increase the fuel economy of their fleets. One of the methods for improving fuel economy is lightweighting vehicles through the use of materials with high strength to weight ratios. Some of these new metals entering the automotive sector are difficult to machine and cause drastically reduced tool life and increase machining cost. It has been shown that electricity has the ability to reduce cutting force during orthogonal cutting and turning. In this research, a design of experiments study on an electrically assisted drilling operation is conducted to determine the impact and interaction between the following input parameters: applied electric current, feedrate, spindle speed, and number of holes cut. These variables used to determine impact and interaction on the following output variables: flank wear, axial cutting force, and temperature evolution. A 2D finite volume method model is used to predict drilling temperature during the process, and is used to aid in predicting axial force. It is found that electric current can reduce cutting force by 10% for 1008 steel at the cost of increased temperature, however, arcing at initial contact causes increased tool wear at higher current inputs.

Topics: Steel , Drilling
Commentary by Dr. Valentin Fuster
2017;():V001T02A014. doi:10.1115/MSEC2017-2780.

BK7/K9 glass is regarded as a difficult-to-machine material due to its high hardness and high brittleness properties as well as high tool wear rate during machining. Facing to these challenges, an efficient and effective rotary ultrasonic machining (RUM) process, consisting of grinding process and ultrasonic machining process, was provided to process BK7/K9 glass. In this investigation, the effects of ultrasonic power on cutting forces, torque, and edge chipping of surface grinding in RUM of BK7/K9 glass were studied. Results showed that, by introducing ultrasonic vibration to surface grinding process, both cutting forces in feeding direction and in axial direction as well as torque values were reduced. The higher the ultrasonic power was, the lower the forces and torque values would be. Edge chipping, which was detrimental to the qualities of machined slots and would cause high machining cost, was significant reduced with the help of ultrasonic vibration.

Commentary by Dr. Valentin Fuster
2017;():V001T02A015. doi:10.1115/MSEC2017-2863.

Aerospace, automotive and sporting goods manufacturing industries have more interest on carbon fiber reinforced plastics due to its superior properties, such as lower density than aluminum; higher strength than high-strength metals; higher stiffness than titanium etc. Rotary ultrasonic machining is a hybrid machining process that combines the material removal mechanisms of diamond abrasive grinding and ultrasonic machining. Hole-making is the most common machining operation done on carbon fiber reinforced plastics, where delamination is a major issue. Delamination reduces structural integrity and increases assembly tolerance, which leads to rejection of a part or a component. Comparatively, rotary ultrasonic machining has been successfully applied to hole-making in carbon fiber reinforced plastics. As reported in the literature, rotary ultrasonic machining is superior to twist drilling of carbon fiber reinforced plastics in six aspects: cutting force, torque, surface roughness, delamination, tool life, and material removal rate. This paper investigates the effects of tool end angle on delamination in rotary ultrasonic machining of carbon fiber reinforced plastics. Several investigators have cited thrust force as a major cause for delamination. Eventhogh, it is found on this investigation, tool end angle has more significant influence on the delamination in rotary ultrasonic machining of carbon fiber reinforced plastics comparing to cutting force and torque.

Commentary by Dr. Valentin Fuster
2017;():V001T02A016. doi:10.1115/MSEC2017-2864.

Laser-assisted machining (LAM) process is an effective method to facilitate material removal processes for difficult-to-cut materials. In LAM process, the mechanical strength of various materials is reduced by a laser heat source focused in front of the cutting tool during machining. Since the laser heat source is located ahead of the cutting tool, the workpiece is preheated by the heat source. This enables difficult-to-cut materials to be machined more easily with low cutting energy, increasing the machining productivity and accuracy. It is difficult to apply laser-assisted milling (LAMilling) to workpieces having complex shapes, because it is not easy to control laser preheating and the cutting tool path for three-dimensionally shaped workpieces. LAMilling has only been used in limited fields such as single-direction machining of flat surfaces. To apply this process in the industrial field, studies on workpieces having various shapes are needed. This study aims to develop a laser-assisted milling device having multiple axes and to investigate the machining characteristics of several difficult-to-cut materials.

Topics: Lasers , Milling
Commentary by Dr. Valentin Fuster
2017;():V001T02A017. doi:10.1115/MSEC2017-2886.

Modulation assisted machining (MAM) superimposes a low-frequency oscillation onto the cutting process. The otherwise continuous cutting is transformed into a series of discrete, intermittent cutting events. A primary benefit of this process is to form discrete chips of small sizes and hence to improve chip evacuation. For applications in drilling the ability to control the chip size offers a direct route to improving process efficiency and stability. In this paper, the MAM process is evaluated for drilling applications via systematic experiments in drilling copper and Ti6Al4V with a two-flute twist drill and a single-flute gun drill. Based on the measurement of thrust force and examination of chip morphology, the continuous cutting and intermittent cutting regimes of MAM are determined experimentally in the normalized frequency and amplitude parameter space. The results are compared with those predicted by the kinematic model of MAM. Furthermore, the results clearly demonstrate the effect of chip morphology control on chip evacuation and process stability in drilling. The modulation conditions leading to the best performance in chip evacuation are discussed. The study shows that MAM is a promising process for enhancing the efficiency and stability in drilling difficult-to-cut materials and/or holes with high length-to-diameter ratio.

Commentary by Dr. Valentin Fuster
2017;():V001T02A018. doi:10.1115/MSEC2017-2935.

The hard turning process is widely used in automobile and heavy machinery industries. Extreme cutting conditions like high temperature and tool wear rate, are associated with the hard turning process. Cubic boron nitride (CBN) cutting tool is generally preferred for hard machining operations. However, higher tool cost, and tool failure due to thermal shock limits its widespread usage. In machining performance analysis, tool wear is an important parameter which is directly related to the cost of the machining process. Previous studies have reported the improvement in tool life by using cryogenic coolant as a cutting fluid. Objective of this paper is to investigate the effect of cryogenic cooling on the tool wear of CBN and Ti-coated alumina ceramic cutting tools used in the hard turning of AISI 52100 hardened steel. High pressure cryogenic jet (HPCJ) module was optimized and configured to use it for hard turning case. Computational fluid dynamics (CFD) based simulation was used to test and optimize the nozzle design for the flow of cryogenic coolant. It was validated by fundamental heat removal test. Ceramic and CBN cutting tools were then used for hard turning of parts using HPCJ module. Flank wear lengths for various cooling conditions were measured and analyzed. It was observed that the higher tool life of a Ti-coated alumina ceramic can be achieved under cryogenic cooling technique, as compared to the CBN insert under dry conditions. Cost analysis of these hard turning cases was also conducted to check the feasibility of its usage under realistic shop floor conditions. It was observed that the machining using Ti-coated ceramic under cryogenic jet may reduce the total tooling cost compared to CBN cutting tool conducted under dry conditions.

Commentary by Dr. Valentin Fuster
2017;():V001T02A019. doi:10.1115/MSEC2017-3014.

Surface hardening was performed by laser surface remelting of AISI H13 tool steel samples using a high power fiber laser. The surface hardened samples were exposed to different tempering temperature of 500°C, 700 °C and 900 °C in a furnace for one hour and brought back to room temperature in still air and by water quenching. Changes of the laser remelted and hardened layer were investigated in terms of microstructure and hardness before and after exposure to different tempering temperatures. Laser remelting caused mainly dendritic microstructure at the top layer but the dendritic structure of the remelted layer got altered after tempering at high temperatures. Air and water quenching caused almost similar result during tempering of laser remelted layer. The microhardness variations along depth after tempering at different temperatures indicates that the surface hardening imparted by laser remelting remains almost intact up to 700 °C but gets destroyed at 900 °C. Although the experimental temperature limits gives approximate threshold values, but it provides a clear indication of a safe limit for laser surface hardened components in high temperature applications like hot-forging dies and friction stir welding tool, etc.

Commentary by Dr. Valentin Fuster
2017;():V001T02A020. doi:10.1115/MSEC2017-3046.

With the increasing demands in the automotive industry for passenger safety and higher structural strength and stiffness, the automotive industry is using more advanced high strength steels. The ability to reduce tool wear and drilling forces in post forming drilling of high strength steel parts is of high importance to the automotive industry. Electrically assisted drilling is a process in which electric current is passed through the drill bit to the workpiece resulting in local softening, and allowing for a reduction in cutting forces and potential increase in tool life. In this paper, tungsten carbide (WC)-tipped drill bits are used to study the effect of varying electrical current on 1500 Usibor® steel work pieces. The effects of current on the drilling process of high strength steel are investigated in this research by studying the maximum temperature during drilling, the dependence of chip formation, tool wear and the axial force during the drilling operation. It was found that the magnitude of current passed through the workpiece directly influences the axial force that the tool experiences, and thus the tool wear. This effect is modeled through Joule heating, leading to elevated temperature and thermal softening.

Topics: Machining , Steel , Drilling , Boron
Commentary by Dr. Valentin Fuster
2017;():V001T02A021. doi:10.1115/MSEC2017-3062.

The ever-increasing industry innovation demands a paradigm of manufacturing process that is capable of accomplishing multiple tasks on a single component. Majority of structural parts require bending of metal sheets with high degree of accuracy. In many applications bent parts with additional features are sought out for various special purposes. Clearly there is a need calling for the integration of different manufacturing processes to reach a synergistic effect [4, 5]. Traditionally a combination of additive manufacturing and machining is used to alleviate the constraints set forth by machining alone. However this hybrid approach is still constrained by both the limited cutter accessibility and gravity-imposed deposition direction. This paper presents a new Hybrid Manufacturing configuration by combining bending, deposition and machining processes. The major advantage of this new approach hinges on the deliberate use of bending process by providing additional accessibility that is not available on traditional additive – machining setup. Essentially the accessibility issue is overcome by introducing an intermediate bending step so that both metal deposition and removal can be conducted in the process-required orientation. As bending is part of this new hybrid process, springback is also inherent to this new hybrid manufacturing approach. This research incorporates the consideration of both springback compensation and cold hardening effect in the selection of intermediate bending step. Examples are also provided to show the efficacy of this new hybrid manufacturing approach.

Commentary by Dr. Valentin Fuster

Processes: Advances in Modeling, Analysis, and Simulation of Manufacturing Processes

2017;():V001T02A022. doi:10.1115/MSEC2017-2621.

Four-dimensional (4D) printing is a new category of printing that expands the fabrication process to include time as the forth dimension, and its process planning and simulation have to take time into consideration as well. The common tool to estimating the behavior of a deformable object is the finite element method (FEM). Although FEM is powerful, there are various sources of deformation from hardware, environment, and process, just to name a few, which are too complex to model by FEM. This paper introduces Geometry-Driven Finite Element (GDFE) as a solution to this problem. Based on the study on geometry changes, the deformation principles can be drawn to predict the relationship between the 4D-printing process and the shape transformation. Similar to FEM, the design domain is subdivided into a set of GDFEs, and the principles are applied on each GDFE, which are then assembled to a larger system that describes the overall shape. The proposed method converts the complex sources of deformation to a geometric optimization problem, which is intuitive and effective. The usages and applications of the GDFE framework have also been presented in this paper, including freeform design, reserve design, and design validation.

Commentary by Dr. Valentin Fuster
2017;():V001T02A023. doi:10.1115/MSEC2017-2673.

The deviations of cylinder bore dimensional accuracy have tremendous influence on engine performances including friction power loss, vibration, leak tightness between piston ring and cylinder wall, and abrasive resistance. Many researches were devoted to capturing cylinder dimensional accuracies by honing using analytical, experimental and simulation methods. These researches investigated the topography and roughness of the honed surface, the relationship between the process parameters and the dimensional accuracies. However, most researches focused on macro-scale dimensional accuracy and micro-scale surface texture respectively. To overcome the limitation, a multi-scale model for cylinder bore honing is proposed to predict the dimensional accuracy and surface texture of cylinder bore at macro-scale and micro-scale simultaneously. The model integrates the microscale factors of the honing stone abrasives distribution characteristics, abrasive wear process, previous cylinder surface topography, and macro-scale factors of cylinder geometry and honing head motion trajectory. A Force matching method is adopted to determine the feed depth of cylinder honing process. Thus the model can predict the roundness, cylindricity, roughness and Abbott-Firestone curve of the honed cylinder bore at multi-scale levels. Simulation results show that material removal distribution is closely related to cylinder bore initial shape deviations. The deviations with long wavelengths cannot be eliminated by the sequential honing.

Commentary by Dr. Valentin Fuster
2017;():V001T02A024. doi:10.1115/MSEC2017-2674.

Adhesive is widely used in engine, airplane and other industry parts to bond and seal machined joint surfaces. Adhesive performance is important and mechanically complex, closely related to the adhesive material property, bonding process and topography of machined surfaces. The effects of material properties, bonding process, and the geometry and dimensions of adhesive layer on adhesive performance have been well studied in adhesive research field. However, the effect of the topography of machined surface on sealing performance was somehow neglected in literature. On the other hand, the texture of machined surface, especially at micro-level of surface roughness, usually used as the objective to determine process parameters in machining and also regarded as indicators of machining productivity, has been systemically and sufficiently studied. However sealing performance has not been widely investigated to relate to topography of machined surface generated from machining operation. Actually, the surface topography plays an important role in the both fields as an index for machining process and also a factor for functional performance. Desired surface should be determined firstly and then machining parameters are designed properly to achieve the desired surface, in order to improve the functional behavior such as the applied adhesive sealing performance of machined components. This research has objectives: 1) the desired surface topography is determined based on the relationship between machining operation and surface texture; 2) The effects of machined surface topography on the reliability of adhesive joint surfaces are analytically investigated. Thus, the research provides a systematic thinking for the selection of surface topography and parameters of face milling operation to improve the performance of adhesive bonding and sealing for its industry implementation.

Commentary by Dr. Valentin Fuster
2017;():V001T02A025. doi:10.1115/MSEC2017-2712.

Chatter identification is necessary in order to achieve stable machining conditions. However, the linear approximation in regenerative chatter vibration is problematic because of the rich nonlinear characteristics in machining. In this study, a novel method to detect chatter is proposed. Firstly, measured cutting force signals are decomposed into a set of intrinsic mode functions by using ensemble empirical mode decomposition. Hilbert transform is following to extract the instantaneous frequency. Fast Fourier transform is also utilized for each intrinsic mode function to determine the intrinsic mode function that contains rich chatter. Finally, the standard deviation and energy ratio in frequency domain of intrinsic mode functions are found as simply dimensionless chatter indicators. The effectively proposed approach is validated by analyzing the machined surface topography and also compared to the stability lobe diagram.

Commentary by Dr. Valentin Fuster
2017;():V001T02A026. doi:10.1115/MSEC2017-2721.

During an induction hardening process, the electromagnetic field generated by the inductor creates eddy currents that heat a surface layer of the part, followed by spray quenching to convert the austenitized layer to martensite. The critical process parameters include the power and frequency of the inductor, the heating time, the quench delay time, the quench rate, and the quench time, etc. These parameters may significantly affect case depth, hardness, distortion, residual stresses, and cracking possibility. Compared to a traditional hardening process, induction hardening has the advantages of low energy consumption, better process consistency, clean environment, low distortion and formation of beneficial residual stresses. However, the temperature gradient in the part during induction hardening is steep due to the faster heating rate of the surface and the aggressive spray quench rate, which leads to a high phase transformation gradient and high magnitude of internal stresses. Quench cracks and high magnitude of residual stresses are more common in induction hardened parts than those of conventional quench hardening processes. In this study, a scanning induction hardening process of a large part made of AISI 4340 with varying wall thickness is modeled using DANTE. The modeling results have successfully shown the cause of cracking. Based on the modeling results, a preheat method is proposed prior to induction heating to reduce the in-process stresses and eliminate the cracking possibility. This process modification not only reduces the magnitude of the in-process tensile stress, but also converts the surface residual stresses from tension to compression at the critical inner corner of the part, which improves the service life of the part. The modified process has been successfully validated by modeling and implemented in the heat treating plant.

Commentary by Dr. Valentin Fuster
2017;():V001T02A027. doi:10.1115/MSEC2017-2741.

The distortion and dimensional instability are the main problems in the machining of thin-walled parts with high-strength aluminum alloys. To ensure the accuracy of aircraft assembly, distortion correction process is essential. Bilateral rolling process has been widely used to correct the distorted parts in the aerospace industries due to the introduction of proper plastic deformation and residual stresses. However, the generation and redistribution mechanism of residual stresses in bilateral rolling correction process remains unclear. This internal mechanism was investigated by finite element method (FEM) in this paper. First, FE models were verified by experiments in terms of residual stresses and strain. Then, simulation results (e.g. plastic strain, true strain and part distortion) were extracted for further analysis. It was shown that the residual stresses are produced in the compatibility process of plastic and elastic strain, and a large plastic deformation can lead to a high amplitude residual stresses. Besides, the binding force from the surrounding materials also results in higher strain gradient and amplitude of residual stresses. Although part distortion has little effect on the limit value of residual stresses, it greatly influences the redistribution of the residual stresses.

Commentary by Dr. Valentin Fuster
2017;():V001T02A028. doi:10.1115/MSEC2017-2759.

The prediction of the grinding process result, such as the workpiece surface quality or the state of the edge zone depending on the used grinding wheel is a great challenge for todays manufacturers and users of grinding tools. This is mainly caused by inadequate predictability of the forces and temperatures acting in the process, which depend on the topography of the grinding wheel coming into contact with the workpiece during the grinding process. The topography of a grinding wheel depends, beside the dressing process, on the structure of the grinding wheel, which is determined by its recipe-dependent volumetric composition. The structure of a grinding tool therefore determines its application behavior strongly. As a result, the knowledge-based prediction of the grinding wheel topography and its influence on the machining behavior is only possible if the recipe-dependent grinding wheel structure is known.

In this paper, an innovative approach for modeling the grinding wheel structure and the resultant grinding wheel topography is discussed. The overall objective of the underlying research project was to create a mathematical-generic grinding wheel model in which the spatial arrangement of the components grains, bond and pores is simulated in a realistic manner starting from the recipe-dependent volumetric composition of a grinding wheel. With this model it is possible to determine the resulting grinding wheel structure and the grinding wheel topography of vitrified and synthetic resin-bonded CBN grinding wheels and thus to predict their application behavior. The originality of the present research results is a generic approach for the modeling of grinding wheels, taking into account the entire grinding wheel structure and build up the topography based on it. Using original mathematical methods, the components of grinding wheels were analyzed and distribution functions of the components were determined. Thus the statistical character of the grinding wheel structure was taken into account. In future, the presented model opens new perspectives in order to optimize and to increase the productivity of grinding processes.

Commentary by Dr. Valentin Fuster
2017;():V001T02A029. doi:10.1115/MSEC2017-2798.

In this paper, numerical investigation of the effects of microgroove textured cutting tools in high speed machining of AISI 1045 is conducted using Finite Element Method (FEM). Microgrooves are designed and fabricated on the rake face of cemented carbide (WC/Co) cutting inserts. The effects of microgroove width, edge distance (the distance from cutting edge to the first microgroove), and microgroove depth are examined and assessed in terms of main cutting force, thrust force, and tool-chip contact length. It is found that microgrooved cutting tools generate lower cutting force and consequently lower the energy necessary for machining. This research provides insightful guidance for optimizing tool life and reducing energy consumption in high-speed machining of AISI 1045 steel.

Commentary by Dr. Valentin Fuster
2017;():V001T02A030. doi:10.1115/MSEC2017-2860.

To estimate the heat flowing into the workpiece in machining processes, an inverse algorithm based on the Conjugate Gradient Method (CGM) is proposed to estimate the unknown boundary heat flux. Outgoing from infrared temperature measurements the heat flowing into the work-piece for an orthogonal cut can be estimated. To increase convergence of the estimated solution, a sensitivity analysis of the direct problem is performed to determine the identifiability of the boundary heat flux on the measurement site. The proposed Fixed Identifiability Conjugate Gradient Method (FIX-CGM) computes a step size function considering the identifiability of the unknown boundary condition to minimize the objective function. In contrast, the CGM computes a scalar step size by integrating the difference between measured and calculated temperature over time. Results show that applying the FIX-CGM for a benchmark case with a step heat flux faster convergence, better accuracy and less sensitivity to noise are achieved.

Commentary by Dr. Valentin Fuster
2017;():V001T02A031. doi:10.1115/MSEC2017-2878.

Manufacturing methods and procedures are advancing through research and development, to optimize machine tools, machining strategies, and the overall manufacturing system. In the aerospace industry, machining distortions, or the deviation of part shape from the original intent after being released from a fixture, occur, reducing productivity. Residual stresses locked into the workpiece are a primary factor contributing to machining distortions. The residual stresses are induced by prior material processing steps such as rolling, forging, heat treating, etc. — which are needed in the aerospace industry for high strength.

Machining distortions result in significant economic losses due to reworking, remanufacturing, and/or rejecting components in the manufacturing and aerospace industries. Quenched 7050 T74 aluminum was used to investigate material removal with respect to milling distortions. Using material with a known residual stress profile, a prismatic u-shape geometry was machined and distortions were characterized, quantified, and described in detail. This paper shows a transparent and repeatable method for characterizing distortion for machined parts. The results from the distorted u-shapes indicate similar characteristics from distortion due to bulk residual stresses and machining factors.

Commentary by Dr. Valentin Fuster
2017;():V001T02A032. doi:10.1115/MSEC2017-2891.

Laser shock peening (LSP) is a surface engineering technique, which aims to increase the fatigue life of various metallic components by inducing compressive residual stress at or near their surface. The finite element method (FEM) is used to identify the most suitable parameters in LSP. Various explicit analyses with artificial material damping are used to attain quasistatic equilibrium between laser shots. Dynamic relaxation (DR) is a well-known conventional technique that uses constant artificial damping to settle an excited model to quasi-static equilibrium. In contrast, the recently developed “Single Explicit Analysis using Time-Dependent Damping” (SEATD) method employs variable damping and performs better in terms of simulation time and accuracy. While recent study has shown that a variable damping profile used in the SEATD technique is beneficial for an LSP set up, identifying the most suitable variable damping profile in general is still ambiguous, given the variety of possible set-ups and boundary conditions. In this paper, a systematic procedure to strive for the best variable damping profile is developed, based on the excited modal parameters of the model. The simulation results are compared with those of an optimum constant damping profile developed using the conventional dynamic relaxation technique, as well as for the best variable damping profile based on exhaustive trial-and-error. The simulation case studies involve circular LSP shot(s) of 5.5 mm diameter spot size applied to Al 2024-T351 aluminum alloy plate under different boundary conditions. Dissipation rates of stain energy, kinetic energy, and total energy and the accuracy of surface residual stresses are investigated to compare the performance of different damping profiles. The results indicate that the proposed method involving modal analysis to systematically identify a variable damping profile, to promote simulation efficiency, appears to work well.

Commentary by Dr. Valentin Fuster
2017;():V001T02A033. doi:10.1115/MSEC2017-2906.

As cutting tool penetrates into workpiece, stress waves is induced and propagates in the workpiece. This paper aims to propose a two-dimensional discrete element method to analyze the stress waves effects during high speed milling. The dependence of the stress waves propagation characteristics on rake angle and cutting speed was studied. The simulation results show that the energy distribution of stress waves is more concentrated near the tool tip as the rake angle or the cutting speed increases. In addition, the density of initial cracks in the workpiece near the cutting tool increases when the cutting speed is higher. The high speed milling experiments indicate that the chip size decreases as the cutting speed increases, which is just qualitatively consistent with the simulation.

Topics: Simulation , Stress , Waves , Milling
Commentary by Dr. Valentin Fuster
2017;():V001T02A034. doi:10.1115/MSEC2017-2932.

In this paper, the commercial FEM software package Abaqus is used to investigate the effects of microgrooved cutting tools in high speed orthogonal cutting of AISI 1045 steel. Microgrooves are designed and fabricated on the rake face of cemented carbide (WC/Co) cutting inserts. A coupled Eulerian-Lagrangian (CEL) finite element model is developed based on Abaqus to solve the evolution of the cutting temperature, chip morphology, cutting force, and phase constitutes simultaneously. This model is validated by comparing the numerical results with the experimental data for orthogonal high speed cutting of AISI 1045 steel with various cutting conditions. In addition, this model is also validated by comparing with the experimental data of regular tool and microgrooved cutting tool under the cutting speed of 120m/min. This validated CEL FEM model is then utilized to investigate the effects of microgrooved cutting tools on the phase transformation, cutting force, cutting temperature, and chip morphology in high speed orthogonal cutting of AISI 1045. The effects of microgroove width, edge distance (the distance from cutting edge to the first microgroove), and microgroove depth are examined and assessed in terms of cutting force, cutting temperature, chip morphology, and phase transformation. It is found that this CEL FEM model can capture the essential features of orthogonal high speed cutting of AISI 1045 using microgrooved cutting tools. It is also concluded that microgrooved cutting tools can not effectively reduce the cutting force in high speed machining, which is contrary to the conclusion obtained for low speed machining in previous research. However, microgrooves on the rake face have influence on the austenite percentage in the chip near the rake face. This research provides insightful guidance for optimizing the cutting performance in terms of cutting temperature, cutting force, chip morphology, and phase transformation in high speed machining of AISI 1045 steel.

Commentary by Dr. Valentin Fuster
2017;():V001T02A035. doi:10.1115/MSEC2017-2939.

Modern computer technology enables people to simulate additive manufacturing (AM) process at high fidelity, which has proven to be an effective way to analyze, predict, and design the AM processes. In this paper, a new method is proposed to simulate the melting process of metal powder based AM. The physics is described using partial differential equations for heat transfer and Laminar flow. The level set methods are employed to track the motion of free surface between liquid and solid phases. The issues, including free surface evolution, phase changes, and velocity field calculation are investigated. The convergence problem is examined in order to improve the efficiency of solving this multiphysics problem.

Commentary by Dr. Valentin Fuster
2017;():V001T02A036. doi:10.1115/MSEC2017-2997.

Cutting temperature plays an important role in micro-scale cutting process because the dimension of the micro-milling cutter is relatively small and the wear of micro-milling cutter is sensitive to temperature. Considering the sidewall of a groove is formed by main cutting edge of the tool, and the bottom of a groove is formed by tool tip and the edge on the end of the tool. Therefore, effects of tool nose corner radius and main cutting edge radius on cutting temperature in micro-milling process cannot be ignored. However, few studies have been conducted on this issue. The effects of tool nose corner radius and main cutting edge radius on cutting temperature is investigated. A three-dimensional micro-milling Inconel718 model is established by using the software DEFORM3D. And the influence of tool nose corner radius and main cutting edge radius on the size and distribution of cutting temperature are studied by numerical simulation, which is verified by experiments. The work provide reference for the control of the size and distribution of the cutting temperature during micro-milling process.

Commentary by Dr. Valentin Fuster
2017;():V001T02A037. doi:10.1115/MSEC2017-2999.

Micro-milling tool breakage has become a bottleneck for the development of micro-milling technology. A new method to predict micro-milling tool breakage based on theoretical model is presented in this paper. Based on the previously built micro-milling force model, the bending stress of the micro-milling cutter caused by the distributed load along the spiral cutting edge is calculated; Then, the ultimate stress of carbide micro-milling tool is obtained by experiments; Finally, the bending stress at the dangerous part of the micro-milling tool is compared with the ultimate stress. Tool breakage curves are drawn with feed per tooth and axial cutting depth as horizontal and vertical axes respectively. The area above the curve is the tool breakage zone, and the area below the curve is the safety zone. The research provides a new method for the prediction of micro-milling tool breakage, and therefore guides the cutting parameters selection in micro-milling.

Topics: Micromilling
Commentary by Dr. Valentin Fuster
2017;():V001T02A038. doi:10.1115/MSEC2017-3009.

Injection Molding is among the most popular processes in plastic parts production. Through this process, burn marks and shrinkage play the most significant role in decreasing surface quality as well as increasing costs, especially when manufacturers use this method in order to produce thin-walled plastic parts. In this paper, a new strategy to remove the defects caused by shrinkage and burn marks has been proposed for the injection molding process of a specific plastic part which is used to keep the doors of an automobiles open during the painting process. Burn marks caused by the trapped air inside thin walls of the part were first simulated in MOLDFLOW 2010 software. Next step is to compare the simulation results to results that are obtained from experimental analysis. Then, Burn marks and shrinkage effects were eliminated by optimization of the process which includes mold design revision by means of SOLIDWORKS software, modification of the simulation in MOLDFLOW and the mold modification in workshop environment by improvising some ejector pins in certain points. Furthermore, shrinkage amount of the part after cooling process was calculated by applying Finite Element Method (FEM) and obtained results were used to optimize the design of the mold. Results demonstrate that mold design optimization would be possible through designing flawless molds that contain certain points for trapped air discharge and calculating shrinkage amount by FEM for optimization of design procedure. Results consequently decrease costs as well as providing surface quality improvement.

Commentary by Dr. Valentin Fuster
2017;():V001T02A039. doi:10.1115/MSEC2017-3043.

In this paper, the commercial FEM software package Abaqus is employed to model the novel nanomachining process, Vibration Assisted Nano Impact machining by Loose Abrasives (VANILA), which combines the principles of vibration-assisted abrasive machining and tip-based nanomachining to conduct nano abrasive machining of hard and brittle materials. In this novel nanomachining process, an atomic force microscope (AFM) is used as a platform and the nano abrasives injected in slurry between the workpiece and the vibrating AFM probe impact the workpiece and result in nanoscale material removal. Diamond particles are used as the loose abrasives. The effects of impact speed, angle of impacts, and the frictional coefficient between the workpiece and abrasives are investigated using Abaqus. It is found that the impact speed, impact angle, and frictional coefficient between the silicon workpiece and nanoabrasives have big influence on the nanocavity’s size and depth.

Commentary by Dr. Valentin Fuster
2017;():V001T02A040. doi:10.1115/MSEC2017-3049.

Thermal mechanical loadings in machining process would promote material microstructure changes. The material microstructure evolution, such as grain size evolution and phase transformation could significantly influence the material flow stress behavior, which will directly affect the machining forces. An analytical model is proposed to predict cutting forces during the turning of AISI 4130 steel. The material dynamic recrystallization is considered through Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. The explicit calculation of average grain size is provided in an analytical model. The grain size effect on the material flow stress is considered by introducing the Hall-Petch relation into a modified Johnson-Cook model. The cutting forces prediction are based on Oxley’s contact mechanics with consideration of mechanical and thermal loads. The model is validated by comparing the predicted machining forces with experimental measurements.

Commentary by Dr. Valentin Fuster
2017;():V001T02A041. doi:10.1115/MSEC2017-3058.

Continuously Variable Crown (CVC) shifting mechanisms represent a control technology with wide range of capability to influence the thickness profile and flatness (shape) of metal strip and sheet in rolling-type manufacturing processes. Further, because of the efficiency and extensive control capability to operate on thin-gauge, high-strength ferrous alloys, the 6-high mill with CVC profiles machined onto the intermediate rolls (IR) represents a popular mill configuration. This is because of the large control range for the strip thickness profile and flatness, which results from lateral shifting of the CVC intermediate rolls. However, together with this efficiency and capability comes very complex contact behaviors between the rolls and strip, including highly non-linear contact force distribution, loss of contact, asymmetric roll wear, unwanted strip wedge profiles, and the need to apply corrective roll tilting. Therefore, for most effective industry use of 6-high mills with intermediate roll CVC shifting, a rapid and accurate mathematical rolling model is needed to predict and account for these complex contact behaviors. This paper introduces an efficient roll-stack computational model capable of simulating such rolling mills under steady-state conditions. The model formulation applies the simplified mixed finite element method (SM-FEM), which is adapted to simulate asymmetric 6-high CVC mill contact behaviors. Results for a specific case study compare favorably to those obtained from a large-scale commercial finite element simulation, yet require a small fraction of the associated computational time and effort.

Topics: Rolling mills
Commentary by Dr. Valentin Fuster

Processes: Advances in Nontraditional Manufacturing Processes

2017;():V001T02A042. doi:10.1115/MSEC2017-2626.

Non-contact ultrasonic abrasive machining (NUAM) is a variant of ultrasonic machining (USM). In NUAM, material is removed predominantly by cavitation erosion in abrasive slurry. Due to a significantly lower material removal rate than traditional USM, NUAM is investigated for its applicability on surface modification and finishing in this study. Experiments were conducted on SUS304 steel samples machined by wire electrical discharged machining (WEDM). Due to the thermal spark phenomenon during WEDM, a thermal recast layer, of thickness approximately 15 μm, is often left over on the specimen’s surface after the process. The undesired thermal recast layer contributes to the poor surface integrity of specimens. A NUAM system was configured using a 40 kHz ultrasonic system. Ultrasonic vibration amplitude of 70 μm at the horn tip was used to generate cavitation bubbles in the abrasive slurry. NUAM was found to be effective in removing the unstable thermal recast layers by means of cavitation erosion. As a result, the average surface roughness, Ra, of the specimens improved from approximately 2.5 μm to ∼1.7 μm after 20 minutes of processing time. Furthermore, the addition of abrasive particles was observed to aid in more efficient removal of thermal recast layers than a pure cavitation condition.

Commentary by Dr. Valentin Fuster
2017;():V001T02A043. doi:10.1115/MSEC2017-2678.

Nanofibers can be used in such fields/applications as medical care, environment protection, apparel, and agriculture. We also believe this field will continue to show fast growth in the next few years. In this paper, we focused an abrasive machining application for oil adsorbing and polishing performances that achieved polymeric nanofiber mass production by a melt blowing method. In the present report, we proposed an oil adsorption physical model and compared experiment results to develop a nanofiber polishing pad. We used this model and calculated the mass ratio of oil to abrasive grains and abrasive size in abrasive machining when the fiber mass and bulk density were constant. For realizing a free-form nano surface, such as a molding die surface, we conducted base experiments with different fiber diameters and grain sizes and compared the base polishing characteristics with commercial felt buff. The polished surface roughness of the workpiece became smaller, and the polishing processes on it were more stable with this new, low cost abrasive material on abrasive machining. We believe that the nanofiber abrasive pad can be used in abrasive machining with oil slurry as a next-generation abrasive material.

Commentary by Dr. Valentin Fuster
2017;():V001T02A044. doi:10.1115/MSEC2017-2723.

The water guided laser micro-jet (LMJ) is a new potential method to machine aero engine parts with much less heat affected area and faster cutting speed than dry laser machining. The focus of this paper is to investigate the energy density and material removal for a dual-laser LMJ system. Then, the effects of dominated parameters on the energy density of LMJ are analyzed. Finally, a mathematical model is developed to describe the relationship between dominant laser parameters with the energy density of LMJ and material removal rate followed by machining case studies of aero engine components.

Commentary by Dr. Valentin Fuster
2017;():V001T02A045. doi:10.1115/MSEC2017-2726.

Carbon fiber reinforced plastic (CFRP) composites have superior properties, including high strength-to-weight ratio, high modulus-to-weight ratio, high fatigue resistance, etc. These properties make CFRP composites being popular in many kinds of industries. Due to the inhomogeneous and anisotropic properties, and high abrasiveness of the reinforcement in CFRP composites, they are classified as difficult-to-cut materials in surface grinding processes. Many problems (including high cutting force and low machining efficiency) are generated in conventional surface grinding processes. In order to reduce and eliminate these problems, rotary ultrasonic machining (RUM) surface grinding of CFRP composites is conducted in this investigation. Effects of ultrasonic power in different machining levels are of great importance in RUM surface grinding processes. However, no investigations on effects of ultrasonic power in different machining levels are conducted in such a process. This investigation, for the first time, tests the effects of ultrasonic power on output variables, including cutting force, torque, and surface roughness in different machining levels. This paper will provide guides for future research on effects of ultrasonic power in different combinations of machining variables on output variables.

Commentary by Dr. Valentin Fuster
2017;():V001T02A046. doi:10.1115/MSEC2017-2781.

The magnetic abrasive finishing (MAF) process is well known because of its high efficiency in yielding a mirror gloss finish zone. Clarification of the high efficiency machining mechanism has indicated that this high efficiency is obtained by iron particle cutting and the simultaneous polishing of alumina abrasives. This process yields unevenness, which is often evident on the workpiece surface. In a previous report, we compared magnetic polishing brushes consisting of iron powder paste (commercial paste) or steel balls (uniform size), and found that a large variation was generated when the magnetic polishing brush approached the workpiece surface in both cases. In this paper, we make slight changes to the steel-ball shape, obtaining saddle and barrel-shaped iron particles via stamping processing. The aim is to observe the control factor of the pressing force for these three different iron particle shapes and for different particle numbers, using a force sensor and a high-speed camera. The relationship between the iron particle shape, the iron particle number and the pressing force control is also explored in an attempt to discuss the mechanism behind the iron particle shape effect on the frictional force generation between the iron particles. It is found that the force variation can be reduced by adjusting the particle shape and number, which effectively reduces the damage caused when the brush approaches the workpiece surface.

Commentary by Dr. Valentin Fuster
2017;():V001T02A047. doi:10.1115/MSEC2017-2927.

Surface integrity of high performance components has a profound influence on the final performance. Therefore, surface integrity is a key point for realizing high performance manufacturing by which manufacture processes and parameters can be pre-selected according to a required functional performance of components, i.e., solving inverse problem of manufacturing, as long as correlations could be established respectively for between processes and surface integrity, and between surface integrity and performance. However, in practice it is still difficult in correlating processes to performance through surface integrity, due to the material and geometry constraints hindering achievability of a desired surface integrity during conventional manufacturing as well as the complex influence of multiple surface integrity parameters on a final performance. In this study, thermally sprayed WC-10Ni coatings onto stainless steel using high velocity oxy-fuel (HVOF) spraying process are investigated to identify the surface integrity predominantly determining the water-lubricated wear performance of coated steel, and then to correlate it to process parameters. The controllable surface integrity facilitates identifying responsible surface integrity parameters for a required high performance, and subsequently deriving necessary process parameters for achieving the desired responsible surface integrity. Specifically, HVOF process parameters are adjusted by changing the oxygen-to-fuel (O/F) ratio to control thermal and mechanical processing loads, i.e. temperature of heated in-flight spraying powders and impact velocity of the molten splats onto stainless steel to form the coatings. Surface features including porosity and phase structure, and surface characteristics including hardness, elastic modulus, and fracture toughness were studied with respect to the wear performance. The porosity and WC phase composition of coatings are identified responsible for the wear performance, as two essential surface integrity parameters that in turn greatly affect the surface characteristics including coating hardness, elastic modulus and fracture toughness. Consequently, the process parameter O/F is feasibly correlated to wear resistance through the responsible surface integrity parameters, as elucidating the coating formation mechanism of influence of particle velocity and temperature on the coating porosity and WC decomposition.

Commentary by Dr. Valentin Fuster
2017;():V001T02A048. doi:10.1115/MSEC2017-2965.

In order to inspect the condition of micro milling cutter automatically and accurately in the on-line process, a dedicated micro milling cutter condition inspection system was established in this paper, which includes an on-machine inspection device and a controller. The key methods of the automatic dimension measurement and the cutting edge condition inspection for micro milling cutters are studied. The proposed methods can measure cutter diameter and clamping height, classify tool type as well as inspect cutting edge condition from both radial and axial direction. The experiments verify that the proposed methods and the developed inspection system can fulfill the needs of industrial applications.

Commentary by Dr. Valentin Fuster
2017;():V001T02A049. doi:10.1115/MSEC2017-2993.

Alumina powder was sprayed on low carbon steel substrate using atmospheric plasma spray process. Two different powders namely crushed and agglomerated powders were used and current was varied to study their effect on fracture toughness. Theoretically, with increase in arc current, melting of ceramic oxide shall increases and in turn dense coating should form. However, it was observed that if the arc power is too high and particle size of the powder being small (∼ 30 μm), the particles tend to fly away from the plasma core. Similarly, particle size distribution and powder morphology also affects the coating properties. Smaller particle should allow more melting resulting in dense coating and agglomerated powder allows flowability as well as better coating efficiency. Conversely, smaller particles tend to fly away from the plasma making the process difficult while the agglomerated particles showed a bimodal structure marked by presence of unmelted region in the splat core. All these factors lead to substantial variation in the fracture toughness of the coating. The present paper attempts to correlate plasma spraying parameters and microstructure of the coating with fracture toughness of the same.

Commentary by Dr. Valentin Fuster
2017;():V001T02A050. doi:10.1115/MSEC2017-3035.

Bioceramics with porous microstructure has attracted intense attention in tissue engineering due to tissue growth facilitation in the human body. In the present work, a novel manufacturing process for producing hydroxyapatite (HA) aerogels with a high density shell inspired by human bone microstructure is proposed for bone tissue engineering applications. This method combines laser processing and traditional freeze casting in which HA aerogel is prepared by freeze casting and aqueous suspension prior to laser processing of the aerogel surface with a focused CO2 laser beam that forms a dense layer on top of the porous microstructure. Using the proposed method, HA aerogel with dense shell was successfully prepared with a microstructure similar to human bone. The effect of laser process parameters on surface and cross-sectional morphology and microstructure was investigated in order to obtain optimum parameters and have a better understanding of the process. Low laser energy resulted in fragile surface with defects and cracks due to low temperature and inability of laser to fully melt the surface while high laser energy caused thermal damage both to surface and microstructure. The range of 40–45 W laser power, 5 mm/s scanning speed, spot size of 1 mmm and 50 % overlap in laser scanning the surface yielded the best surface morphology and micro structure in our experiments.

Commentary by Dr. Valentin Fuster
2017;():V001T02A051. doi:10.1115/MSEC2017-3072.

The micro/nano textured cemented carbide surface of different wettability was produced by laser scanning and fluorinated treatment. The tribological properties of the un-textured, oleophobic and oleophilic micro/nano textured surface were investigated experimentally including the effects of crank speed and contact pressure by a reciprocating friction and a wear tester. For all tested surfaces, the friction coefficient of the surface decreased as both the increasing crank speed and contact pressure increased. Compared to the un-textured surface, the friction coefficient of the micro/nano textured surface was significantly decreased, being sensitive to the wettability of the surface. Besides, the tribological properties of the oleophobic micro/nano textured surface were superior to the oleophilic micro/nano textured surface under the same experimental conditions. The improvement in tribological properties of the oleophobic micro/nano textured surface could be attributed to the low wettability, which was beneficial to rapid accumulation of the lubricating oil on the surface.

Topics: Tribology , Lasers
Commentary by Dr. Valentin Fuster

Processes: Innovations in Materials Forming Processes

2017;():V001T02A052. doi:10.1115/MSEC2017-2615.

Combined Extrusion-Forging process is a renowned metal forming method which serves as a pathway for manufacturing components of complex design. In that context processing a component with better mechanical and metallurgical properties can be enhanced by severe plastic deformation which processes the fine-grained materials formation in the product. These fine-grained materials achieved by SPD makes the component with superior quality. The novelty of the concept is to validate the presence of fine-grained materials at lower ram displacement. This paper presents the estimated forming load, metal flow pattern and alike, using aluminum 1072 as billet material for manufacturing SCCCH, along with micro-structural validation by experimental die-punch setup and simulation using modelling software DEFORM3D. Numerical analysis was also performed to estimate the forming load and metal flow patterns. Good number of experiments has been carried out at various punch movements to find out forming load and metal flow pattern. Microscopic analyses have been performed to validate the data with the results obtained from the experimentation. It was found that the numerical data was well validated with the experimental results. Further, Micro-hardness analysis was also performed. As the component was manufactured on application of heavy loads, the residual stress was also found to check the load carrying capacity of the component.

Commentary by Dr. Valentin Fuster
2017;():V001T02A053. doi:10.1115/MSEC2017-2644.

Ball burnishing is a process used to smooth rough surfaces. For not rotational symmetric parts, the process is typically conducted on milling machines. Since it is an incremental process, it is relatively time consuming. Therefore, a rolling tool is developed, which superposes the rotation of the milling spindle with the feed of the machine to increase the rolling velocity. In order to achieve constant rolling forces, hydrostatic ball burnishing tools are used. Within this work, the influence of this tool concept on the processing time as well as on the leveling of surface irregularities is investigated. This is achieved by a comparison with a conventional ball burnishing process. Finally, the rotating tool is used to investigate the influence of high rolling speeds on the leveling of the surface. All experiments were carried out with thermally coated specimens. A model for calculating the strain rates at the roughness peaks during ball burnishing is derived. For the experiments carried out with the rotating rolling tool, rolling velocities of 50,000 mm/min were realized. Calculations with the developed model showed that this results in local strain rates at the roughness peaks of up to 1,384 s−1. In addition, the flow stresses at the roughness peaks were calculated. Compared with quasi static experiments, the flow stress drops to less than the half under high velocities. This results in a better leveling of the surface for rolling velocities between 10,000 mm/min and 25,000 mm/min. A further rise of the rolling speed increases the flow stress again and thereby reduces the possible leveling.

Commentary by Dr. Valentin Fuster
2017;():V001T02A054. doi:10.1115/MSEC2017-2690.

The influences of dislocation magnification due to plastic deformation and solute atoms concentration on the electroplastic effect were investigated. It is found that the dislocation magnification due to plastic deformation will enhance the electroplastic effect. The electroplastic effect of Al-Cu alloy was enhanced with the increase of plastic deformation and current density. Moreover, the solute atoms concentration has a great effect on the electroplastic effect. The influence of electrical current pulse on Portevin-Le Chatelier (PLC) effect of Al-Cu alloy is also reported.

Commentary by Dr. Valentin Fuster
2017;():V001T02A055. doi:10.1115/MSEC2017-2715.

A novel process which combines casting with forging during one process was proposed to improve mechanical properties and refine microstructure. The microstructure evolution of as-cast samples and forged samples were analyzed by optical microscope and scanning electron microscope (SEM). The tensile properties and micro-hardness were also measured. The results show that combination of casting and forging can improve microstructure and decrease porosity of casting samples, consequently contributing to a better fatigue performance. The ultimate tensile strength and elongation were increased after forging process, however, the yield strength and micro-hardness decreased.

Commentary by Dr. Valentin Fuster
2017;():V001T02A056. doi:10.1115/MSEC2017-2774.

Cold rotary forging is an innovative incremental metal forming process whose main characteristic is that the workpiece is only partially in contact with a conical tool, reducing therefore the required forging loads. However, in spite of many benefits of such a process, wide industrial implementation of rotary forging is not possible without proper understanding of material behaviour. In the present work, the capability of rotary forging process was explored for the manufacturing of flared cylindrical parts by cold forming. Another main aim was to assess the cold formability of high-strength materials for aerospace applications (martensitic stainless steels) under incremental processes. In order to understand the impact of rotary forging on the final properties of formed components, microstructural and mechanical analysis were performed. Microstructural and hardness analysis were conducted on both axial and transverse sections along the cold formed flange in order to study the grain flow orientation and strain distribution. In a similar fashion, mechanical test specimens were machined from different positions and orientations along the rotary forged component. Further analysis was performed on the components in the as-treated condition in order to understand the response of cold-worked Jethete M152 components to subsequent heat treatments.

Microstructural and hardness analysis clearly reveals a strong grain reorientation and strain localization around “pickup“ defects (material attached to the upper tool) observed on the flange top surface, close to the flange edge. These results suggest that an excessive deformation is localized during the early stages of the flange formation. Another characteristic feature found in the rotary forged parts is the presence of a buckling phenomenon which appears in later stages of the rotary forging process. Strain hardening along with the increasing flange length requires higher levels of forging loads to keep forming the flange. This results into a significant accumulation of compressive stresses in the transition region between the flange and the straight region. Gradually the resultant compressive force exceeds the critical buckling load, leading to the occurrence of the buckling phenomenon. This latter issue determines the limit of the cold flaring process. This can help to determine the maximum length of the flange part, achievable in this process, which is of great importance for the design of these manufacturing technologies. From the mechanical testing results, large differences were found as a function of both position and orientation (axial, transverse) throughout the rotary forged components (anisotropic properties). Concerning the impact of heat treatments on cold-worked components, no differences were found in the as-treated condition, in terms of microstructural and mechanical properties between regions with a large difference in strain distribution. These results denote the normalizing effect of conventional hardening treatments on cold-worked Jethete M152 components, restoring the homogenous and isotropic properties across the whole component.

Commentary by Dr. Valentin Fuster
2017;():V001T02A057. doi:10.1115/MSEC2017-2797.

To study the influence of non-isothermal deformation on microstructure, texture and mechanical properties, the CP Ti sheets were rolled to approximately 10% reduction per pass under a pair of rolls with different surface temperatures (i.e. non-isothermal rolled). The progress of recrystallization was enhanced with the increase of the difference in surface temperature between upper and lower rolls. When CP Ti sheets were non-isothermally rolled under the upper and lower rolls with surface temperatures of 210 and 120 °C, respectively, complete recrystallization occurred. Under such circumstances, it was found that the microstructure consists of equiaxed grains with the average size of 13μm and with mainly high-angle boundaries. Pyramidal <c+a> slip was the dominant deformation mechanism, and the elongation at room temperature was three times of that in the initial state. However, CP Ti sheets were rolled under a pair of roll with the same surface temperatures of 120 or 210 °C (i.e. isothermal rolled), recrystallization did not occur, and the microstructure, texture and mechanical properties of CP Ti isothermal rolling sheets were similar to those of conventional hot rolled CP Ti sheets.

Commentary by Dr. Valentin Fuster
2017;():V001T02A058. doi:10.1115/MSEC2017-2826.

Micro and multiscale material properties are one area that must be considered in order to satisfy the need for increased utilization of miniature devices manufactured with microscale hydroforming processes. The objective of the present research is to evaluate the properties of 0.2-mm thick AISI 304 stainless steel using circular dies of 5 mm and 11 mm diameter and elliptical hydraulic bulge forming processes with minor diameters of 11 mm and various aspect ratios. Macroscale analytical methods for circular dies were compared to experimental results. For the elliptical dies, Banabic’s method and a new modification of Banabic’s method, utilizing work by Rees were used to obtain power law material properties. The Ekineev-Kruglov method was shown to be the best analytical method estimating material properties from circular dies. For elliptical dies, based upon finite element simulations, it was seen that Banabic’s method resulted in the best agreement with experimental results. However, it was found that neither method for elliptical dies resulted in reasonable dome height predictions compared to those from microscale tensile tests.

Commentary by Dr. Valentin Fuster
2017;():V001T02A059. doi:10.1115/MSEC2017-2956.

In this study, the forming limit of aluminum alloy sheet materials are predicted by developing a Ductile Failure Criterion (DFAC). In the DFAC, the damage growth is defined by Mclintock formula, stretching failure is defined at Localized Necking (LN) or Fracture without LN, while the critical damage is defined by a so-called effect function, which reflects the effect of strain path and initial sheet thickness. In the first part of this study, the DFAC is used to predict Forming Limit Curves of six different aluminum sheet materials at room temperature. Then, the DFAC is further developed for elevated temperature condition by introducing an improved Zener-Hollomon parameter (Z′), which is proposed to provide enhanced representation of the strain rate and temperature effect on limit strain. In warm forming condition, the improved DFAC is used to predict the FLCs of Al5083-O and failure in a rectangular cup warm draw process on Al5182+Mn. Comparison shows that all the prediction matches quite well with experimental measurement. Thanks to the proposal of effect function, the DFAC only needs a calibration at uniaxial tension and thus provides a promising potential to predict forming limit with reduced efforts.

Commentary by Dr. Valentin Fuster
2017;():V001T02A060. doi:10.1115/MSEC2017-3026.

To date, the industrial production of metal foam components has remained challenging, since few methods exist to manufacture metal foam into the shapes required in engineering applications. Laser forming is currently the only method with a high geometrical flexibility that is able to shape arbitrarily sized parts. What prevents the industrial implementation of the method, however, is that no detailed experimental analysis has been done of the metal foam strain response during laser forming, and hence the existing numerical models have been insufficiently validated. Moreover, current understanding of the laser forming process is poor, and it has been assumed, without experimental proof, that the temperature gradient mechanism (TGM) from sheet metal forming is the governing mechanism for metal foam.

In this study, these issues were addressed by using digital image correlation (DIC) to obtain in-process and post-process strain data that was then used to validate a numerical model. Additionally, metal foam laser forming was compared with metal foam 4-point bending and sheet metal laser forming to explain why metal foam can be bent despite its high bending stiffness, and to evaluate whether TGM is valid for metal foam.

The strain measurements revealed that tensile stretching is only a small contributor to foam bending, with the major contributor being compression-induced shortening. Unlike in sheet metal laser forming, this shortening is achieved through cell wall bending, as opposed to plastic compressive strains. Based on this important difference with traditional TGM, a modified temperature gradient mechanism (MTGM) was proposed.

Topics: Lasers , Metal foams
Commentary by Dr. Valentin Fuster
2017;():V001T02A061. doi:10.1115/MSEC2017-3029.

The manufacturing of gear elements by forming offers advantages regarding the resulting mechanical properties of the functional components. One possible approach is offered by the incremental sheet-bulk metal forming of gears using a linear motion punch. This method is highly flexible in terms of shape and position of the functional elements to be produced, but inefficient from an economical point of view due to the high process time. This paper presents a new sheet-bulk gear forming process using rotating tools in order to speed up the manufacturing process of load-adapted gears. Here, different concepts with rotating tools being synchronized and non-synchronized to the workpiece are investigated to form high-strength, load-adapted gears made of bainitic steel BS600. The focus is on the analysis of the occurring material flow which is examined by means of finite element analysis and microstructural investigations to ensure the manufacture of fully functional geared components by this sheet-bulk metal forming process.

Topics: Flow (Dynamics)
Commentary by Dr. Valentin Fuster
2017;():V001T02A062. doi:10.1115/MSEC2017-3036.

Automotive and aerospace industries are interested in implementing die-less forming processes in order to reduce part costs and the required forming energy. One method of die-less forming is incremental forming, in which a sheet metal part is formed; typically with a hemispherical tool that deforms material as it pushes into the material and passes along the surface to create the desired part geometry. One problem with incremental forming is global springback, which occurs after the part has been formed and is released from the forming fixture. This effect is caused by residual stresses that are created during part deformation and result in geometric inaccuracies after the clamping force has been released. In this paper, the effect of post-deformation applied direct current on the springback of pre-formed sheet metal will be investigated. This is a process is a type of electrically assisted manufacturing (EAM). This paper is a continuation of previous works presented at MSEC 2015–2016. The initial feasibility study described herein already achieves a springback reduction of 26.3% and is dependent on the regions of high stress concentration as well as current density. Future work will extend this reduction through further testing of complex configurations.

Commentary by Dr. Valentin Fuster
2017;():V001T02A063. doi:10.1115/MSEC2017-3037.

Electrically assisted incremental sheet forming (EAIF) is a novel addition to the incremental forming (IF) method. One variation of this approach applies direct electrical current during forming. Many improvements over tradition IF can be seen by utilizing this method, to include greater part accuracy, reduced forming force, and greater formability.

In order to maximize the effects of electrically assisted incremental forming, all parameters of the method must be investigated, including the polarity of the current passing through the part and the path that the applied current takes. The effects of altering these two parameters is the primary investigation in this research.

It was determined that, in order to optimize springback reduction and formability during electrically assisted single point incremental forming, the tool should be assigned the positive electrode and the center of the workpiece should be assigned the negative electrode. Additionally, the mechanism behind the spalling effect inherent to EAIF is discussed.

Commentary by Dr. Valentin Fuster
2017;():V001T02A064. doi:10.1115/MSEC2017-3045.

Continuous-Bending-Under-Tension (CBT) is an experimental technique that has been shown to increase elongation-to-fracture by over 100% in aluminum alloys and over 300% in steel as compared to uniaxial tensile tests [1]. This procedure is a modified form of a tensile test in which a specimen experiences 3 point plastic bending, induced by traversing 3 rollers back and forth over the gauge length, while simultaneously being pulled in tension. This process is able to delay the occurrence of necking in pure tension by suppressing the instability. Thus, significantly more elongation is achieved in the specimen prior to fracture. In this paper, an experimental investigation of key process parameters, i.e., bending depth and pulling speed, during CBT testing of AA6022-T4 is presented. The load cycle during a CBT test will also be discussed along with the strain induced throughout the gauge length.

Topics: Tension
Commentary by Dr. Valentin Fuster

Processes: Scalable Nanomanufacturing Processes

2017;():V001T02A065. doi:10.1115/MSEC2017-2638.

In this work, a sodium-cobalt oxide (NaxCo2O4) ceramic composite nanofiber was manufactured through electrospinning. The response of the fiber to external electromagnetic field was characterized to observe the heat generation in the fiber. In addition, we also measured the current passing through the fiber under the polarization of DC potential. It is found that the fiber has intensive heating behavior when it is exposed to the electromagnetic field. The temperature increases more than 5 degrees in Celsius scale only after 5 s exposure. The current – potential curve of the fiber reveals its dielectric behavior. It is concluded that this ceramic fiber has the potential to be used for hyperthermia treatment in biomedical engineering or for energy conversions.

Commentary by Dr. Valentin Fuster
2017;():V001T02A066. doi:10.1115/MSEC2017-2681.

Massively parallel electron beam lithography may be an alternative manufacturing method in semiconductor industry if the issues of the multi electron beam source are addressed. The microcolumns are suitable for the massively parallel electron beam lithography because of their compactness and the ability to achieve high spatial resolution. A new design with varying apertures for our recent nanoscale photoemission source is presented here. Given the easiness of the fabrication of the microcolumn, we optimized the parameters of the design and found that the resolution can be improved by changing the ratio between the diameters of the focus and extractor electrodes.

Commentary by Dr. Valentin Fuster
2017;():V001T02A067. doi:10.1115/MSEC2017-2739.

Copper sulphide (CuxS, x = 1 to 2) is a metal chalcogenide semiconductor that exhibits useful optical and electrical properties due to the presence of copper vacancies. This makes CuxS thin films useful for a number of applications including infrared absorbing coatings, solar cells, thin-film electronics, and as a precursor for CZTS (Copper Zinc Tin Sulphide) thin films. Post-deposition sintering of CuxS nanoparticle films is a key process that affects the film properties and hence determines its operational characteristics in the above applications. Intense pulse light (IPL) sintering uses visible broad-spectrum xenon light to rapidly sinter nanoparticle films over large-areas, and is compatible with methods such as roll-to-roll deposition for large-area deposition of colloidal nanoparticle films and patterns. This paper experimentally examines the effect of IPL parameters on sintering of CuxS thin films. As-deposited and sintered films are compared in terms of their crystal structure, as well as optical and electrical properties, as a function of the IPL parameters.

Commentary by Dr. Valentin Fuster
2017;():V001T02A068. doi:10.1115/MSEC2017-2972.

The development of accurate, noncontact surface imaging is key to implementing an effective metrology strategy to manage defect detection in high volume flexible electronic device fabrication. This paper presents the design of a compound, double parallelogram flexure-hinge mechanism (DPFM) based nanopositioning system with stacked coarse-fine adjustment DPFMs. In concert with novel Atomic Force Microscope (AFM)-on-a-chip technology, this coupled, multi-flexure positioning system is proposed as a probe-based metrology device for roll-to-roll (R2R) electronics manufacturing and shown in Fig. 1 [1], [2].

The structural parameters of this system have been designed to ensure the desired stiffness, range of motion, and resonant modes are achieved. The parametric design of this positioning system has been verified through Finite Element Analysis (FEA). The proposed system will achieve a scanning throughput of six, 60 μm line scans every 0.15 seconds for a total throughput of over 75 μm2/s at a lateral resolution nearing 50 nm and a vertical resolution of less than 20 nm. This will allow for the development of a statistical metrology framework to reliably measure and analyze nanofeatured, R2R manufactured, flexible electronics in a cost-effective manner and provide fast, continuous defect identification.

Commentary by Dr. Valentin Fuster
2017;():V001T02A069. doi:10.1115/MSEC2017-3059.

This paper presents graphene growth on Pt deposited on four different adhesion layers such as Ti, Cr, Ta, and Ni. During the graphene growth at 1000 °C using conventional Chemical Vapor Deposition method, these adhesion layers diffuse into and alloy with Pt layer resulting graphene to grow on different alloys. Therefore, Pt layer on different adhesion layers induces different quality and number of layer(s) of graphene grown on the film. Monolayer graphene was produced on majority of metal layers except on Pt/Ta layer where bilayer graphene is observed. The lowest defects were found on graphene grown on Pt/Ni film where slightly higher number of wrinkles are observed compared to other alloys. We characterized graphene using SEM images of transferred graphene, of Pt grains after the growth of graphene, and of in-depth profiles of thin film via TOF-SIMS. Our paper states feasibility of graphene growth on Pt thin film on various adhesion layers and obstacles to overcome to enhance graphene transfer from Pt thin film. We address one of the major difficulties of graphene growth and transfer to implement graphene in NEMS/MEMS devices.

Commentary by Dr. Valentin Fuster

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