Accepted Manuscripts

Sinan Kesriklioglu, Cory Arthur, Justin D. Morrow and Frank E. Pfefferkorn
J. Manuf. Sci. Eng   doi: 10.1115/1.4044035
The objective of this work is to fabricate thermocouples directly on the rake face of a commercially available tungsten carbide cutting insert for accurately measuring the tool-chip interface temperature during metal cutting. The thermocouples are sputtered onto the cutting insert using micro machined stencils, are electrically isolated with layers of Al2O3, and receive a top coating of AlTiN for durability. The result is a non-sacrificial thermocouple junction that is approximately 1.3 µm below the rake face of the tool and 30 µm from the cutting edge. Experimental and numerical characterization of the temperature measurement accuracy and response time are presented. The instrumented cutting tool can capture the tool-chip interface temperature transients at frequencies of up to 1 MHz, which enables observation of serrated chip formation and adiabatic shear events. Temperature measurements from oblique machining of 4140 steel is presented and compared with three-dimensional, transient numerical simulations using finite element analysis, where cutting speed and feed are varied. This method of measuring the tool-chip interface temperature shows promise for future research and smart manufacturing applications.
TOPICS: Temperature measurement, Thermocouples, Cutting, Temperature, Transients (Dynamics), Durability, Finite element analysis, Junctions, Micromachining, Tungsten, Machining, Coating processes, Coatings, Steel, Computer simulation, Manufacturing, Metal cutting, Cutting tools, Shear (Mechanics)
Li Zixuan and Shu Xue-dao
J. Manuf. Sci. Eng   doi: 10.1115/1.4044007
In industrial production, the roller trace design is still based on the trial-and-error method which is more like an art than science. In this paper, we establish the mathematical model of the involute curve roller trace and adopted the forming clearance compensation in the attaching-mandrel process. The backward pass roller trace is optimized considering that the blank springback may interference the roller. The spinning simulation model of seven forming passes is set up and verified by the experiments with superalloy GH3030. The wall thickness, strain distribution and tool forces are analyzed. The results show that the forming clearance compensation can greatly shorten the forming time, enhance the production efficiency and saving energy. The metal accumulates at the edge of the blank and the maximum thinning zone is appeared near the edge and is easy to crack. In the straightening pass, the tool forces of both the roller and mandrel are larger than the other passes.
TOPICS: Spinning (Textile), Spin (Aerodynamics), Clearances (Engineering), Design, Optimization, Rollers, Blanks, Simulation models, Wall thickness, Errors, Fracture (Materials), Metals, Superalloys
Lei Li, Haihong Huang, Fu Zhao, Xiang Zou, Qi Lu, Yue Wang, Zhifeng Liu and John W. Sutherland
J. Manuf. Sci. Eng   doi: 10.1115/1.4043982
Studies have indicated that reducing process energy demand is as important as improving energy conversion efficiency to make manufacturing equipment more energy efficient. However, little work has been done to understand the energy demand characteristics of the widely employed drawing process. In this paper, the energy demand of the cylindrical drawing process under a range of operating parameters was measured and analyzed. Since any energy saving efforts should not have negative effects on product quality, forming quality of the drawn part indicated by the maximum thinning and thickening ratios and variation of thickness was also considered. To identify the main contributors to energy demand and forming quality, two sets of experiments were designed based on the Taguchi method. The first set of experiments include three parameters (i.e., punch velocity, blank holder force, and drawn depth) at three levels, while the second set of experiments only include two factors (i.e. punch velocity and blank holder force) at three levels due to their impacts on forming quality. Analysis of variance (ANOVA) and analysis of means (ANOM) were then used to analyze the experimental results. Finally, grey relational analysis (GRA) was used to reveal the correlation between forming quality and process energy. Results show that the mean thickness variation has the strongest relational grading with process energy, which suggests that process energy can be used as an effective indicator to predict mean thickness variation of the drawn part.
TOPICS: Product quality, Energy conversion, Production equipment, Stainless steel, Taguchi methods, Blanks
Ze Liu, Benxin Wu, Zheng Kang and Zhen Yang
J. Manuf. Sci. Eng   doi: 10.1115/1.4043979
Laser micromachining has several advantages such as the capability of flexibly producing very small features in both conductive and non-conductive materials. However, it may often suffer from induced defects, such as debris deposition on workpieces. To improve laser micromachining, a novel machining process, called “ultrasound-assisted water-confined laser micromachining” (UWLM), was proposed by the corresponding author. The ultrasound during UWLM can be applied through different approaches, such as an ultrasonic horn or a high intensity focused ultrasound (HIFU) transducer, which can be called horn- and HIFU-based UWLM, respectively. This is the first paper (to the authors' best knowledge) reporting experimental studies on microhole drilling using the novel HIFU-based UWLM process. In this study, drilled workpieces have been characterized; and in-situ time-resolved shadowgraph imaging and pressure measurement during the UWLM process have been performed. Under the investigated conditions, it has been found that the microholes drilled by HIFU-based UWLM under suitable conditions appear reasonably clean without significant debris depositions often seen for nanosecond (ns) laser ablation in air. The UWLM process can produce much larger average ablation depths per pulse than laser ablation in water without ultrasound (e.g., for copper the former depth can be up to more than 6 times the latter). The study has revealed one important mechanism for the enhanced ablation depth, which is introduced in more details in the paper.
TOPICS: Lasers, Drilling, Ultrasound, Micromachining, Water, Laser ablation, Ablation (Vaporization technology), Machining, Pressure measurement, Transducers, Imaging, Copper
Cunfu Wang, Xiaoping Qian, Bill Gerstler and Jeff Shubrooks
J. Manuf. Sci. Eng   doi: 10.1115/1.4043978
The paper studies how to control boundary slope of optimized parts in density-based topology optimization for additive manufacturing (AM). Boundary slope of a part affects the amount of support structure required during its fabrication by additive processes. Boundary slope also has direct relation with the resulting surface roughness from the AM processes, which in turn affects the heat transfer efficiency. By constraining the minimal boundary slope, support structures can be eliminated or reduced for AM, and thus material and post-processing costs are reduced; by constraining the maximal boundary slope, high surface roughness can be attained, and thus the heat transfer efficiency is increased. In this paper, the boundary slope is controlled through a constraint between the density gradient and the given build direction. This allows us to explicitly control the boundary slope through density gradient in the density-based topology optimization approach. We control the boundary slope through a single global constraint. Numerical examples on heat conduction problem, and coupled 2D and 3D thermoelastic problems demonstrate the effectiveness and efficiency of the proposed formulation in controlling boundary slopes for additive manufacturing. Experimental results from metal 3D printed parts confirm that our boundary slope based formulation is effective for controlling part self-support during printing and for affecting surface roughness of the printed parts.
TOPICS: Surface roughness, Optimization, Topology, Additive manufacturing, Density, Heat transfer, Metals, Manufacturing, Heat conduction, Printing, Thermoelasticity

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