The International Journal of Advanced Manufacturing Technology

Natarajan, Jawahar; Sivasankaran, R.; Kanagaraj, G.

doi: 10.1007/s00170-017-1232-ypmid: N/A

This paper presents bi-criteria formulation of a tolerance allocation model for an interchangeable assembly to simultaneously evolve suitable combination of manufacturing facility in multiple facility shaft-hole production environments of medium- and large-scale industries and tolerances to complement the need of customers. An Exhaustive Search Procedure is used to obtain the optimal solution for small and medium size problems and simulated annealing algorithm is used for large size problems. The usefulness of the Pareto front in manufacturing tolerance allocation decisions is demonstrated with three case study problems. The effect of process capability of shaft-hole assembly manufactured from alternative manufacturing machines and the optimality is analyzed in three cases to understand their criticality in decision-making. The models discussed in this paper could be useful for medium- and large-scale manufacturing industries, where there will be a variety of manufacturing facilities (specifications, capabilities, models, and types) for making both shaft-hole assembly and play a key role to meet the tolerance and cost requirements of different customers. This paper further discusses how this formulation and methodologies can be used for two hole and two shaft assemblies and multiple shaft-hole assemblies. Finally, the paper ends with highlighting directions of future research avenues in the shaft-hole assembly.

Chen, Feng; Gao, Xing; Yue, Xiao; Tong, G.

doi: 10.1007/s00170-017-1240-ypmid: N/A

Copper electrodes are commonly employed in micro-resistance spot welding (MRSW), a dominant process used to join ultra-thin metallic sheets. During welding, some copper from the electrodes inevitably diffuses into the spot welds, changing the chemical compositions and properties of the resulting welded joints. In this study, 0.05-mm-thick Ti alloy metallic sheets were welded via MRSW under various combinations of welding parameters (ramping time, welding time, holding time, welding current, and electrode force). The effects of these welding parameters on electrode elemental diffusion were investigated via elemental analysis. Elemental composition of welded joints was measured via energy-dispersive spectrometry after tensile-shear tests. No copper was detected in the heat-affected zone or base material, but the amount of copper in the welding nuggets varied significantly with the welding parameters. Moreover, comparing copper element and hardness maps in weld nugget, the welding nugget hardness increased when more copper diffused into it.

Lu, Dun; Liu, Sanli; Li, Xuewei; Wu, Diaodiao; Zhao, Wanhua; Lu, Bingheng

doi: 10.1007/s00170-017-1243-8pmid: N/A

Tool path generation is one of the key challenges in multi-axis sculptured surface machining. Besides geometry accuracy, machining processes have been considered in tool path generation in order to improve machining quality and efficiency as far as possible. However, so far, the machine tool accuracies have not been yet fully taken into account during tool path generation. Contour accuracy is one of the most important precision indexes to guarantee the machining quality of sculptured surfaces. One of the major reasons causing contour error is the dynamic mismatch between feed axes of machine tools. In this study, the mathematic relationship between the cutting direction, dynamic mismatch of feed axes and contour error is theoretically established. The mathematic relationship can be used to calculate the optimal cutting directions which minimize the contour error caused by dynamic mismatch between feed axes during machining a sculptured surface by a three-axis machine tool. A machining experiment is carried out to verify the mathematic relationship. In the experiment, the tool paths are generated along the optimal cutting direction and other cutting directions for comparison. The results show that the contour error under the case of the optimal cutting direction is much smaller than that under the other cases.

Rezaei, Hamed; Sadeghi, Mohammad; Budak, Erhan

doi: 10.1007/s00170-017-1329-3pmid: N/A

To optimize the machining process, finding the minimum uncut chip thickness is of paramount importance in micro-scale machining. However, strong dependency of the minimum uncut chip thickness to the tool geometry, workpiece material, tool-work friction, and process condition makes its evaluation complicated. The paper focuses on determination of the minimum uncut chip thickness experimentally during micro-end milling of titanium alloy Ti-6Al-4V with respect to influences of cutting parameters and lubricating systems. Experiments were carried out on a CNC machining center Kern Evo with two flute end mills of 0.8 and 2 mm diameters being used in the tests for micro- and macro-milling, respectively. It was found that the micro-milling caused more size effect than macro-milling due to higher surface micro-hardness and specific cutting forces. The specific cutting force depended strongly on feed rate (f z) and lubricating system, followed by depth of cut (a p) and cutting speed (v c), mainly in the micro-scale. All output parameters were inversely proportional to the specific cutting force. Finally, depending on different process parameters during micro-milling of Ti-6Al-4V, the minimum uncut chip thickness was found to vary between 0.15 and 0.49 of the tool edge radius.

Zheng, Yong; Liu, Dong; Yang, Yanhui; Zhang, Zhe; Li, Xiaolong

doi: 10.1007/s00170-017-1135-ypmid: N/A

As one of the incremental bulk metal forming, the main plastic metal flow of axial closed die rolling (ACDR) process consists of the axial compression and circumferential torsion. The key difference between the ACDR and forging processes should be concentrating on the plastic deformation zone (PDZ) evolution, especially on the condition of thermal deformation. Therefore, the verified FEM and corresponding experiment have been proposed to find out the systematic rule of PDZ. The thermal parameter distribution of the workpiece has been explored to obtain the PDZ evolution at different deformation extent. PDZ evolution mode has also been proposed, and the distribution of microstructure/hardness is given to the evidence of PDZ mode. The results show that the PDZ spreads from the contact area of the upper surface of the lower/side surface in ACDR process. Multiple thermal parameter evolution in ACDR process could be found through the analysis of microstructure morphology. Also, microstructure orientation could be the fundament of PDZ evolution. The cooling rate and the periodic evaluation of thermal parameters should be the main factors for the microstructure evolution, including the distribution of lamellar α and globular α. Then, the extent and range of PDZ could be defined through the observation and analysis of hardness evolution.

Zhang, Hongyu; Huang, Jin; Wang, Jianjun; Zhao, Jiayong; Liu, Dachuan

doi: 10.1007/s00170-017-1239-4pmid: N/A

A conductive pattern is formed by a conductive material on the substrate having an electromagnetic function. Ink-jet printing using metal nanoparticles is an attractive method for the direct fabrication of a conductive pattern, with low-cost, low-waste, and simple process. The conductive pattern that is usually fabricated on complex surface substrates is widely used, but this method has several drawbacks like stacking of printing curves to the surface and complexity of the motion path; moreover, the conductive inks flow easily on the surface, resulting in low printing accuracy. In addition, each curve needs to be individually cured leading to a long interface, thus resulting into the decrease in conductivity. In this pursuit, the current work presents a reduced dimension patch printing method, which uses a series of patches to approach the surface. These patches were rotated to the horizontal plane through the five-axis motion system for printing and curing by turn, so that the surface printing gets converted to two-dimensional printing. To execute this method, we designed the print path planning algorithm as follows: initially, based on the topological relation of the triangles in the STL (stereolithography) model, the sub-region culling method was used to reduce the number of final patches and the length of the boundary, as well as to improve the conductivity. Subsequently, the patches were rotated to the horizontal plane for optimizing the print path, by turn according to the adjacent relation, thus achieving the ink-jet process in two-dimensional motion. This improved the efficiency and ensured that the conductive inks were always on the horizontal plane before curing, thus effectively avoiding its flow and improving the printing precision. Additionally, the patch was integrally cured to improve the overall connectivity. The results show that the algorithm could achieve the print path planning and significantly reduce the number of print patches and boundary length.

Yuan, Yanjie; Jing, Xiubing; Ehmann, Kornel; Zhang, Dawei

doi: 10.1007/s00170-017-1278-xpmid: N/A

Micro end-milling is widely used in many industries to produce micro products with complex 3D shapes. The accurate modeling and prediction of surface roughness are important for evaluating the productivity of the machine tools and the surface quality of the machined parts. This paper presents an accurate surface roughness model based on the kinematics of cutting process and tool geometry by considering the effects of tool run-out and minimum chip thickness. The proposed surface roughness model is validated by micro end-milling experiments with the miniaturized machine tool. The results show that the proposed surface roughness model can accurately predict both the trends and magnitude of the surface roughness in micro end-milling.

Provencher, Paul; Balazinski, Marek

doi: 10.1007/s00170-017-1307-9pmid: N/A

Quantitative information about the contributions of individual cutting phenomena to linear roughness profiles may aid in optimizing processes with fewer expensive successive trial parts. Linear roughness profiles of metallic hard turned parts contain feed marks, each mark representing a snapshot in time of the state of the cut. This suggests that roughness measuring machines may be an attractive avenue for offline, inexpensive, non-destructive, quantitative evaluation of the time-dependent mechanisms active during the cut. Principal component analysis of feed marks reveals theoretically expected feed mark deformations without coercing the data by fitting. Novel in this paper, we show that those components of feed mark variability appear to correspond to radial and axial displacement of the cutting tool, ploughing, and side flow. Those components are sufficient to explain nearly all the variability between feed marks. The components are easily idealized in a general manner, and their influences on experimental profiles are quantified as percentage contributions to ordinary roughness parameters.

Zhou, Guanghao; Xu, Guocheng; Liu, Jing; Tian, Yukuo; Gu, Xiaopeng

doi: 10.1007/s00170-017-1338-2pmid: N/A

In this paper, laser welding for the stainless steel lap joint used in the railway vehicle body has been studied based on the analysis of the ultrasonic test. The weld width is evaluated by the analysis of ultrasonic testing signals during the ultrasonic scanning process. The changes of the echo and main frequency are in good agreement with the positions of the probe. The semi-attenuation method and frequency domain analysis are established based on the A-scan signals and frequency spectrum characteristic curves. From the analysis of the error statistics, the frequency domain analysis has a higher accuracy and stability, which can meet the requirements of engineering applications. The equivalent weld width is defined based on the C-scan imaging and the quantitative ultrasonic test is achieved. The tensile shear measurements of welds show that the equivalent weld widths have the same change rules with the values of the tensile shear strength and provide an important basis for the quality evaluation of the laser welding.

Domínguez-Rodríguez, G.; Ku-Herrera, J.; Hernández-Pérez, A.

doi: 10.1007/s00170-017-1314-xpmid: N/A

Acrylonitrile butadiene styrene (ABS) specimens manufactured by fused deposition are tested under uniaxial compression in order to judge the effectiveness of printing orientation, density, and filler patterns in terms of stiffness and strength per printing time. The compressive properties of the 3D printed materials along the three orthogonal directions are studied on cylindrical specimens filled with honeycomb and rectangular patterns. In order to achieve different densities, five filler percentages (0, 20, 30, 40, and 100%) are employed for each type of structure. Specimens filled with honeycomb patterns are stiffer and stronger than those with rectangular patterns only when they are oriented along the applied load. However, structures with rectangular patterns only require roughly half of printing time of those filled honeycomb cells, which yields effective rectangular structures with high elastic properties per printing time. Stress–strain curves reveal that compressive strength and stiffness increase with respect to the structure density. Patterns printed along the loading direction present higher strength and stiffness than on the other orthogonal orientations. Local buckling and compressive failure mechanisms are identified for light weight and heavy structures, respectively. A combination of shear and local buckling failure appeared in honeycomb structures printed transversely with relative densities around 20–40%.