Key Engineering Materials Vol. 825

Abstract: The influence of various process parameters on the building of maraging steel powder by the selective laser melting (SLM) processes is investigated. The microstructure in the built part was observed and the influence of the heat treatment was evaluated. As results, the depth of solidified layer was higher than that of deposited metal powder, and its value was influenced with the process parameters. The microstructure in the boundary between the built part and the substrate was quite different from the built part even if the suitable heat treatment was performed.

Abstract: The aim of this study is to develop a finite element analysis technique to characterize the distributions of temperature and stress in the process of multilayer deposition of metallic powders by laser additive manufacturing (LAM). Simulation results indicate the residual normal stress in the laser moving direction is greater than that in other directions due to a larger temperature gradient, and it increases with number of deposited layers. Highly residual stresses are present in the LAM build and at the base nearby the interface between the build and base.

Abstract: The influence of tool feed conditions on the burnished-surface integrity obtained by roller burnishing, which can generate the sliding effect, adding to the rolling effect at burnishing point, is addressed. A JIS SCM420 steel round bar was used as the workpiece. The surface integrity was improved by feeding the roller in the same direction with the sliding effect and by decreasing the tool feed rate. A better surface was achieved when the roller was fed in the opposite direction to the feed direction of the turning tool in a preceding process of the burnishing.

Abstract: Additive manufacturing (AM) has been commonly used for the prototyping of three-dimensional (3D) models. The input model of the AM technology is a triangular model representing the surface shape of an object. The design features on a triangular model are generally not clear as the vertices are irregularly distributed. If design modification is necessary, it is difficult to segment and extract the meshes from the model. The objective of this study is to propose a method for extracting the design features on an object model by using the texture information. A 3D color model including a triangular model representing the object shape and a texture map describing the object texture is employed. The 3D model is generated by using a set of object images captured from different views surrounding the object. A texture mapping algorithm is then employed to generate the texture map corresponding to the 3D model. With both meshes and texture displayed in a texture mode, a region extraction technique is employed to extract the design features. All parts separated can then be fabricated with an AM machine, and assembled for checking the feasibility of design modification. Several products are employed to demonstrate the feasibility of the proposed technique.

Abstract: In order to improve efficiency of high speed milling, effects of pick feeds of up cutting and down cutting on tool wear and processing characteristics were investigated after cutting pre-hardened steel NAK 55 by TiAlN-coated carbide radius end mill. Flank wear of the tools after up cutting was less than down cutting when the pick feed was smaller than 0.1 mm, which tendency changed when the pick feed was larger than 0.3 mm.

Abstract: This study deals with high quality thermal stress cleavage of thick sapphire wafer with thickness of 5 mm. The influence of the distance from the edge to the initial crack, laser power, and plane orientation on the cleavage characteristics was experimentally investigated. The results indicate that the surface waviness W_a at the cleaved surface was influenced by the distance from the edge. A cleaved surface with good surface characteristics was obtained by cleaving with low laser power. The cleavage direction also affects the cleaved surface characteristics.

Abstract: In this paper, preheating temperature was investigated for the laser assisted machining (LAM) of Inconel 718 under different conditions for the milling test. The experimental results show that the requirement of laser power for the particularly preheating temperature proportionally increased with the table speed. The resultant cutting force for sufficient shearing work material in LAM was lower than conventional machining (CM) approximately 11, 21 and 28% for the cutting speed of 30, 50 and 75 m/min, respectively. The tool wear in LAM could be improved at relatively high cutting speed of 75 m/min and the hardness of machined surface in LAM was slightly higher than CM.

Abstract: The crafts such as lacquerware have made unique strides through decorating techniques using gold such as “Makie”, the technique to draw picture by scattering powdered gold, and “Chinkin”, the technique to rub gold into the design engraved by carving knives. In conventional techniques, practical knowledge and ability are essential to produce craft products. Therefore, screen printing which consists of simple processes has been developed. However, screen printing requires a masking plate made of silk or nylon to create patterns for transcribing ink into objects. This paper presents the formation of a decorative film by inkjet printing with gold nanoparticles for crafts such as lacquerware. The proposed method consists of on-demand process, which makes design changeable without masking. The aims are threefold: 1) to establish a sintering process of gold nanoparticles for acrylonitrile butadiene styrene (ABS) and phenol resin substrates used for synthetic resin products; 2) to characterize the sintered gold film; 3) to examine applicability to industry. The major results obtained are as follows: the appearance and the reflectance spectra of the gold nanoparticle film vary with heat conditions; the proper heat conditions which prevent thermal damage to substrates are the temperature of 373 K or below for the ABS resin substrate, and 423 K or below for the phenol resin substrate, respectively; the gold nanoparticle film possessed a good surface integrity without any voids when the sintering temperature is higher than 323 K for 1 h. Moreover, the film had such a high adhesion to substrates that no separation occurred after cross-cut test; the proposed method applied a lacquerware product made of ABS resin, yielding the decorative film

Abstract: In this study, machining was performed on stainless steel (AISI304) by face-milling. Design of experiment was implemented to develop the experimental layout. The aim of this work was to relate the response to the process parameters. An optimization routine was applied to determine the optimal conditions that would enhance the minimization of the deformation. As a result, mathematical models were developed to determine the relationship between the process parameters and the deformation after machining. The effects of process parameters on the deformation amount were defined.