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Editorial

J. Manuf. Sci. Eng. 2017;140(1):010201-010201-4. doi:10.1115/1.4038522.
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Commentary by Dr. Valentin Fuster

Research Papers

J. Manuf. Sci. Eng. 2017;140(1):011001-011001-15. doi:10.1115/1.4037420.

Wheel position (including wheel location and orientation) in the flute grinding process of an end-mill determines the ground flute's geometric parameters, i.e., rake angle, core radius, and flute width. Current technologies for calculating the wheel position to guarantee the three parameters' accuracy are either time-consuming or only applicable to the grinding wheels with singular points. In order to cope with this problem, this paper presents a generalized and efficient approach for determining the wheel position accurately in five-axis flute grinding of cylindrical end-mills. A new analytic expression of the wheel location is derived and an original algorithm is developed to search for the required wheel position. This approach can apply not only to the wheels with fillets but also to the wheels with singular points. Simulation examples are provided to validate the new approach and compared with the results from other literature. Besides the ability to determine the wheel position, the new approach can evaluate extrema of the core radius and flute width that a specified wheel can generate. Owing to the evaluated extrema, automatic 1V1 wheel customization according to the designed flute is realized in this paper. This work can improve the efficiency and automation degree of the flute grinding process and lay a good foundation for the development of a comprehensive computer-aided design and computer-aided manufacturing system for end-mill manufacturing.

Topics: Grinding , Wheels
Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011002-011002-17. doi:10.1115/1.4037424.

Residual stress, characteristic of surface integrity, is a great issue in cutting process for its significant effects on fatigue life and dimension stability of the machined parts. From a practical viewpoint, residual stress is generated in a dynamic tool-part engagement process, instead of a process with nominal cutting loads. This is the challenge that we have to handle, so as to achieve better predictive methods than the previously recorded approaches in literatures which ignore the dynamic effects on residual stress. This paper presents an analytical method for the prediction of residual stress in dynamic orthogonal cutting. A mechanistic model of the dynamic orthogonal cutting is provided, considering the indentation effect of the cutting edge during the wave-on-wave cutting process. Following the calculation of plastic strains by incremental analysis in mechanical loading, analytical solution of the residual stress due to distributed plastic strains in half-plane is obtained based on inclusion theory. Without relaxation procedures, the two-dimensional (2D) distribution of residual stress in dynamic cutting process is predicted for the first time. A delicately designed dynamic orthogonal cutting experiment is realized through numerical control (NC) lathe. The periodic residual stress distribution is predicted using the proposed approach, which is then validated against the X-ray diffraction measurements.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011003-011003-14. doi:10.1115/1.4037233.

Carbon fiber-reinforced plastics (CFRPs) are sustainable materials compared to others due to their distinctive properties and light weight. On the other hand, producing CFRP products with minimum manufacturing costs and high quality can be quite challenging. This research aims to formulate a mathematical model that determines the optimum manufacturing process/processing parameters and takes into consideration the effect of the selected processes on the quality of panels and the environmental impact surface roughness and percentage of voids are used as metrics to assess the desired quality level of the finished product. Energy consumption is used to quantify the environmental cost. Design of experiment (DOE) was performed to study the effect of varying the process parameters, namely application method, pressure, and temperature on the response variables. Regression models were used to model the response variables. A generalized model was developed and validated both numerically and experimentally. Results signify the need for a systematic approach to determine optimum manufacturing processes without resorting to trial and error.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011004-011004-7. doi:10.1115/1.4037707.

Localized rapid heating process utilizing carbide-bonded graphene-coated silicon molds is a high-efficiency and energy-saving technique for high-volume fabrication of polymer optics. The graphene coating is used as a rapid heating element because of its high thermal conductivity and low electrical resistivity. However, the optical property of molded polymer and its dependence on process conditions such as heat transfer have not been thoroughly investigated. In this research, finite element method (FEM) simulation was utilized to interpret temperature changes of the graphene coating and heat transfer between graphene and polymethylmethacrylate (PMMA) in localized rapid heating. Experiments were then carried out under different voltages to validate the numerical model. In addition, refractive index variation of the PMMA lens resulting from nonuniform thermal history in molding was demonstrated by simulation modeling as well. Finally, wavefront variation of a PMMA lens molded by localized rapid heating was first studied using an FEM model and then verified by optical measurements with a Shack–Hartmann wavefront sensor (SHWFS). The wavefront variation in a PMMA lens molded by conventional method was also measured. Compared with conventional molding process, localized rapid heating is shown to be a possible alternative for better optical performance with a much shorter cycle time.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011005-011005-7. doi:10.1115/1.4037439.

The need for an open, inclusive, and neutral procedure in selecting key performance indicators (KPIs) for sustainable manufacturing has been increasing. The reason is that manufacturers seek to determine what to measure to improve environmental sustainability of their products and manufacturing processes. A difficulty arises in understanding and selecting specific indicators from many stand-alone indicator sets available. This paper presents a procedure for individual manufacturers to select KPIs for measuring, monitoring, and improving environmental aspects of manufacturing processes. The procedure is the basis for a guideline, being proposed for standardization within ASTM International. That guide can be used for (1) identifying candidate KPIs from existing sources, (2) defining new candidate KPIs, (3) selecting appropriate KPIs based on KPI criteria, and (4) composing the selected KPIs with assigned weights into a set. The paper explains how the developed procedure complements existing indicator sets and sustainability-measurement approaches at the manufacturing process level.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011006-011006-11. doi:10.1115/1.4038208.

Tube hydroforming (THF) is an important manufacturing technology for producing tube components by means of fluid pressure. In comparison to other basic forming processes like deep drawing, forming steps can be reduced and more complex shape is allowed. In this work, it was aimed to establish the forming limit curve (FLC) of stainless steel tube grade 304 for the THF process by using finite element (FE) simulations coupled with the Gurson–Tvergaard–Needleman (GTN) damage model as failure criterion. The parameters of the GTN model were obtained by metallography analysis, tensile test, plane strain test of the examined steel in combination with the direct current potential drop (DCPD) and digital image correlation (DIC) techniques. These parameters were well verified by comparing the predicted FLC of steel sheet with the experimental FLC gathered from the Nakazima test. Then, the FLC of steel tube 304 was established by FE simulations coupled with the damage model of tube bulging tests. During the bulge tests, pressure and axial feed were properly controlled in order to generate the left-hand FLC, while pressure and external force needed to be simultaneously incorporated for the right-hand FLC. Finally, the FLC was applied to evaluate material formability in an industrial THF process of the steel tube.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011007-011007-11. doi:10.1115/1.4038205.

Cellular metamaterials are of interest for many current engineering applications. The incorporation of hierarchy to cellular metamaterials enhances the properties and introduces novel tailorable metamaterials. For many complex cellular metamaterials, the only realistic manufacturing process is additive manufacturing (AM). The use of AM to manufacture large structures may lead to several types of manufacturing defects, such as imperfect cell walls, irregular thickness, flawed joints, partially missing layers, and irregular elastic–plastic behavior due to toolpath. It is important to understand the effect of defects on the overall performance of the structures to determine if the manufacturing defect(s) are significant enough to abort and restart the manufacturing process or whether the material can still be used in its nonperfect state. In this study, the performance of hierarchical honeycomb metamaterials with defects has been investigated through simulations and experiments, and hierarchical honeycombs were shown to demonstrate more sensitivity to missing cell walls than regular honeycombs. On average, the axial elastic modulus decreased by 45% with 5.5% missing cell walls for regular honeycombs, 60% with 4% missing cell walls for first-order hierarchical honeycomb and 95% with 4% missing cell walls for second-order hierarchical honeycomb. The transverse elastic modulus decreased by about 45% with more than 5.5% missing cell walls for regular honeycomb, about 75% with 4% missing cell walls for first-order and more than 95% with 4% missing cell walls for second-order hierarchical honeycomb.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011008-011008-15. doi:10.1115/1.4037600.

Introduced is an efficient new model to compute the roll-stack deflections and contact mechanics behaviors for metal rolling mills with asymmetric roll crowns. The new model expands the simplified mixed finite element (FE) method to consider complex antisymmetric contact conditions of continuously variable crown (CVC) roll diameter profiles designed for use with work-roll (WR) shifting on four-high mills, and intermediate-roll (IR) shifting on six-high mills. Conventional roll-stack deflection models are either more computationally expensive or exploit more simplifying assumptions. Moreover, almost all existing approaches fail to adequately simulate the antisymmetric CVC contact problem required for model-based control of thickness profile and flatness in hot and cold CVC rolling mills. The presented model efficiently captures bending, shear, and flattening deformations while computing contact interference forces, binary contact locations, and net effects of roll and strip crowns. Strip thickness profiles and contact force distributions predicted by the new model are checked against known theoretical solutions, and compared to predictions from large-scale FE simulations for a four-high mill with WR CVC shifting, and a thin-strip six-high mill with IR CVC shifting.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011009-011009-12. doi:10.1115/1.4037604.

Laser cladding is a rapid physical metallurgy process with a fast heating–cooling cycle, which is used to coat a surface of a metal to enhance the metallurgical properties of the substrate's surface. A fully coupled thermal–metallurgical–mechanical finite element (FE) model was developed to simulate the process of coaxial powder-feed laser cladding for selected overlap conditions and employed to predict the mechanical properties of the clad and substrate materials, as well as distortions and residual stresses. The numerical model is validated by comparing the Vickers microhardness measurements, melt pool dimensions, and heat-affected zone (HAZ) geometry from experimental specimens' cross sectioning. The study was conducted to investigate the temperature field evolution, thermal cycling characteristics, and the effect of deposition directions and overlapping conditions on the microhardness properties of multitrack laser cladding. This study employed P420 stainless steel clad powder on a medium carbon structural steel plate substrate. The study was carried out on three case studies of multitrack bead specimens with 40%, 50%, and 60% overlap. The results provide relevant information for process planning decisions and present a baseline to the downstream process planning optimization.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011010-011010-10. doi:10.1115/1.4037603.

Fiber-reinforced soft composites (FrSCs) are seeing increasing use in applications involving soft actuators, four-dimensional printing, biomimetic composites, and embedded sensing. The three-dimensional (3D) printing of FrSCs is a layer-by-layer material deposition process that alternates between inkjet deposition of an ultraviolet (UV) curable polymer layer and the stamping of electrospun fibers onto the layer, to build the final part. While this process has been proven for complex 3D geometries, it suffers from poor fiber transfer efficiencies (FTEs) that affect the eventual fiber content in the printed part. In order to address this issue, it is critical to first understand the mechanics of the fiber transfer process. To this end, the objective of this paper is to develop a cohesive zone-based finite element model that captures the competition between the “fiber–carrier substrate” adhesion and the “fiber–polymer matrix” adhesion, encountered during the stamping process used for 3D printing FrSCs. The cohesive zone model (CZM) parameters are first calibrated using independent microscale fiber peeling experiments involving both the thin-film aluminum carrier substrate and the UV curable polymer matrix. The predictions of the calibrated model are then validated using fiber transfer experiments. The model parametric studies suggest the use of a roller-based stamping unit design to improve the FTE of the FrSC 3D printing process. Preliminary experiments confirm that for a 0.5 in diameter roller, this new design can increase the FTE to ∼97%, which is a substantial increase from the 55% efficiency value seen for the original flat-plate stamping platen design. The model has broader applications for the transfer-printing of soft material constructs at the submicron scale.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011011-011011-10. doi:10.1115/1.4037996.

Of various tissues being fabricated using bioprinting, three-dimensional (3D) soft tubular structures have often been the focus since they address the need for printable vasculature throughout a thick tissue and offer potential as perfusable platforms for biological studies. Drop-on-demand inkjetting has been favored as an effective technique to print such 3D soft tubular structures from various hydrogel bioinks. During the buoyancy-enabled inkjet fabrication of hydrogel-based soft tubular structures, they remain submerged in a solution, which crosslinks the printed structures and provides a supporting buoyant force. However, because of the low stiffness of the structures, the structural deformation of printed tubes poses a significant challenge to the process effectiveness and efficiency. To overcome this structural deformation during buoyancy-enabled inkjet printing, predictive compensation approaches are developed to incorporate deformation allowance into the designed shape. Circumferential deformation is addressed by a four-zone approach, which includes base, circular, vertical, and spanning zones for the determination of a designed cross section or compensated printing path. Axial deformation is addressed by the modification of the proposed circumferential compensation based on the distance of a given cross section to the junction of a branching tube. These approaches are found to enable the successful fabrication of straight and branching alginate tubular structures with nearly ideal geometry, providing a good foundation for the wide implementation of the buoyancy-enabled inkjetting technique. While inkjetting is studied herein as a model bioprinting process, the resulting knowledge also applies to other buoyancy-enabled bioprinting techniques.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011012-011012-9. doi:10.1115/1.4037426.

The purpose of this study was to investigate the advantages of laser surface melting for improving wetting over the traditional approach. For comparison, kovar alloy was preoxidized in atmosphere at 700 °C for 10 min, and then wetted with borosilicate glass powder at 1100 °C with different holding time in atmosphere. The proposed approach used a Nd:YAG laser to melt the surface of the kovar alloy sample in atmosphere, then wetted with borosilicate glass powder at 1100 °C with the same holding time. The laser melted surface shows a decrease in contact angle (CA) from 47.5 deg to 38 deg after 100 min. X-ray photoelectron spectroscopy (XPS) analysis shows that the surface and adjacent depth have higher concentration of FeO for laser treated kovar (Kovar(L)) than that on traditional thermal treated kovar (kovar(P)). This is attributed to the following improved wetting and diffusion process. The adhesive oxide layer formed on kovar (L) may enhance the oxygen diffusion into the substrate and iron diffusion outward to form an outside layer. This is an another way to enhance the wetting and diffusion process when compared to the delaminated oxide scales formed on kovar (P) surface. The diffusion mechanisms were discussed for both approaches. Scanning electron microscope (SEM) revealed that an iron oxide interlayer in the joint existed under both conditions. Fayalite nucleated on the iron oxide layer alloy and grew into the glass. In both cases, neither Co nor Ni were involved in the chemical bonding during wetting process. The work has shown that laser surface melting can be used to alter the wetting and diffusion characteristics of kovar alloy onto borosilicate glass.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011013-011013-13. doi:10.1115/1.4038139.

Electro discharge machining (EDM) process need to be optimized when a new material invented or even if some process variables changed. This process has many variables and it is always difficult to get the optimum set of variables by chance. Therefore, an optimization process need to be conducted considering different combinations of machining parameters as well as other variables even if the process were optimized for a certain set of variables. Optimization of the EDM process for machining stainless steel 304 (SS304) (ASTM A240) was studied in this paper. Signal-to-noise ratio (S/N) was calculated for each performance measures, and multi response performance index (MRPI) was generated using fuzzy logic inference system. Optimal machining parameters for machining SS304 materials were identified, namely current 10, pulse on time 60 μs, and pulse off time 35 μs. Analyses of variances (ANOVA) method was used as well to see which machining parameter has significant effect on the performance measures. The result of ANOVA indicates that pulse off time and current are the most significant machining parameters in affecting the performance measures, with the pulse off time being the most significant parameter.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011014-011014-7. doi:10.1115/1.4038206.

Cutting edge microgeometry has gained special attention of late in the machining research community. Machine tool vibration, tool life, and workpiece surface integrity are all influenced by cutting edge size/shape. To optimize the machining process, variable microgeometry (VMG) cutting tools, in which the edge microgeometry varies along the edgeline with respect to specific variables (such as machining parameters or expected tool wear), are manufactured. Despite the advantages of VMG tools, a major hindrance in their development is the manufacturing complexity that demands high precision multi-axis edge preparation processes following extensive machine setup, fixturing, and programming. This paper details the proof of concept of a design criterion, which leads to the manufacturing of VMG cutting tools by only traditional edge preparation processes. The present method relies on the existing relationship between the edge radius subsequent to the edge preparation process and the tool wedge angle. The validity of the proposed method is first examined by a numerical simulation of the edge preparation. Carbide cutting tool inserts are then designed based on the proposed idea. Robust VMG generation subsequent to edge preparation by microblasting is demonstrated through microgeometric measurements. VMG chemical vapor deposition-coated carbide tools manufactured by the proposed approach are evaluated for turning hardened steel, and optimal designs are identified with respect to tool life and workpiece surface roughness. To address the design consideration, finite element (FE) modeling provides valuable insight into the machining process. FE modeled stress and temperature distribution clarify the experimental observations and reveal the design constraints.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011015-011015-15. doi:10.1115/1.4038000.

The dynamic response of thin-walled parts becomes time and tool position dependent due to material removal along the toolpath. This article proposes a new reduced-order workpiece dynamic parameters update model using substructuring and perturbation methods. The removed volumes between discrete locations along the toolpath are defined as substructures of the initial global workpiece. The dynamically reduced-order initial workpiece structure and the removed substructures are obtained with model order reduction techniques. Equations of motion of the workpiece are updated in time-domain by rigidly coupling fictitious substructures having the negative mass and stiffness of the removed material. Instead of solving the generalized eigenvalue problem repeatedly along the toolpath, the mode shapes of the in-process workpiece are perturbed using the mass and stiffness of the removed substructures. Convergence of the perturbation is improved by integrating a vector sequence convergence accelerating algorithm. The corresponding updated mode frequencies are evaluated using Rayleigh Quotient with the perturbed mode shapes. The proposed reduced-order time-domain dynamics update model is verified in five-axis ball-end milling tests on a thin-walled twisted fan blade, and its predictions are also compared against the authors’ previously developed frequency-domain reduced-order model. It is shown that the newly introduced model is ∼4 times more computationally efficient than the frequency-domain model.

Commentary by Dr. Valentin Fuster
J. Manuf. Sci. Eng. 2017;140(1):011016-011016-10. doi:10.1115/1.4037608.

Disassembly is a very important step in recycling and maintenance, particularly for energy saving. However, disassembly sequence planning (DSP) is a challenging combinatorial optimization problem due to complex constraints of many products. This paper considers partial and parallel disassembly sequence planning for solving the degrees-of-freedom in modular product design, considering disassembly time, cost, and energy consumption. An automatic self-decomposed disassembly precedence matrix (DPM) is designed to generate partial/parallel disassembly sequence for reducing complexity and improving efficiency. A Tabu search-based hyper heuristic algorithm with exponentially decreasing diversity management strategy is proposed. Compared with the low-level heuristics, the proposed algorithm is more efficient in terms of exploration ability and improving energy benefits (EBs). The comparison results of three different disassembly strategies prove that the partial/parallel disassembly has a great advantage in reducing disassembly time, and improving EBs and disassembly profit (DP).

Commentary by Dr. Valentin Fuster

Technical Brief

J. Manuf. Sci. Eng. 2017;140(1):014501-014501-10. doi:10.1115/1.4037999.

A capsule-type modular machine tool was developed, which was capable of multifunctional processes with a single setup. This mechanism was designed according to the concept of a reconfigurable machine tool (RMT), which can transform from a machining center to a lathe, and is capable of multiple functional processes, such as laser, milling, and grinding processes. After addressing the kinematics of the machine, a static structural analysis was performed and some ribs were added to enhance the stiffness. A frequency response function (FRF) simulation was conducted on the modified machine and natural frequencies were determined to avoid resonance in processing. Then, an FRF test was performed to find the actual natural frequencies, to confirm the simulation results. After investigating the natural frequencies, high-speed machining was performed to make 300 μm sized patterns.

Commentary by Dr. Valentin Fuster

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