Advanced Materials Research Vols. 774-776

Abstract: An analysis of cutting force performance in the micro milling on steel has been carried out based on an experimental work using micro flat end mills on a precision CNC machine tool. It has been found that cutting forces occurred at low feed per tooth are relatively high by assessing the averaged peak forces from the experiments. When feed per tooth is relatively close to tool edge radius, the forces were not growing in linearity with the increasing feedrate. This finding indicates the significance of ploughing phenomenon as an effect of tool edge radius in micro milling.

Abstract: High-pressure Water Jet Increment Sheet Metal Forming adopt the idea of layered manufacturing to scatter a complex three-dimension shape to many 2-dimension layers along z axis, and then the water jet machine partially on these layers. We did a research on that the distance from square processing trajectory to center and the water pressure affect the limits of forming height by finite element simulation of high-pressure water jet box-shape piece incremental forming with the thought of layered manufacturing. Based on this, puts forward a new method of different 2-dimension layers is loaded on different water pressure to improve water jet incremental forming accuracy. This method was proved feasibility by finite element simulation.

Abstract: PCD diamond cutting tools which named sintering diamond tool is the main cutting tool of the natural granite, the cutting characteristics of that have great influence on machining efficiency and machining quality. At present, most scholars are relatively mature on the research of diamond tool wear condition by the physical attributes of the PCD diamond tool and physical components of natural stone material. This paper studies the impact of cutting parameters on the tool wear, optimization of process parameters.

Abstract: The precision turning experiments of aluminium composites reinforced with SiC whisker reinforcements were done by polycrystalloid diamond (PCD) tools. The measure analysis of the machined surface was carried out with Atom Force Microscope (AFM) and Scan Electronic Microscope (SEM). The roughness values of the machined surface were measured by Talysurf-6. The results show that the orientation of reinforcements in the machined surface will directly affect the deformation mechanism of SiC whiskers, microstructures of the machined surface, and to determine the quality of the machined surface. In the five types from A to E of SiC whisker orientation, the orientation of case A easily makes to produce SiC whisker deformation by cutting off directly, and to result in the best machined surface. However, for the orientation of case E, it easily makes to induce SiC whisker deformation by pulling out or pressing into aluminium matrix, and to produce the worst machined surface.

Abstract: The tiny grinding wheel cluster based on MR effect is an ultra-precision machining tool. The structural optimization and magnetic pole characteristics of machining tool are studied in order to improve its machining performance. In this paper, the Maxwell3D of finite element analysis software is used to simulate and analyze the magnetic field interaction of tiny grinding wheel cluster based on MR effect. A polishing experiment is done, and the results show that the polishing effect in the same polarity is better than that in the opposite polarity.

Abstract: The process parameters of thin strip tandem cold rolling were optimized based on the BP neural network and the genetic algorithm with which the rolling energy consumption required was reduced and could contribute to the rolling force and the thickness control.

Abstract: Rapid Investment Casting can overcome the cost involved in designing and fabrication of metal tooling for wax injection process. The present investigation is aimed to determine the effects of CAD model placement degree and size on the dimension error of prototype base on Selective Laser Sintering. The experimental results show that the dimension change law of length, width and height is different from each other, it mainly due to the intersection angle between important edge and forming plane. When the angle is 0° and 90°, staircase effect is smaller and dimension accuracy is higher, when the angle is 45°, the staircase effect is biggest and dimension accuracy is lowest. The CAD model size has significantly influence on dimension accuracy because of secondary sintering, when the model size is 86mm, the secondary sintering reduces to minimum, the dimension error is 0, the secondary sintering is more obvious with the decrease of CAD model dimension.

Abstract: GGG70L die material laser phase change hardening aims to discover the Quenched Layer performance of the GGG70L die material hardened by the laser of different power. Making comparison and analysis in the experiment and considering the actual production factors such as cost, working efficiency and product quality standard, it is concluded that laser power being 1900 w, laser scanning speed 6mm/s, spot size 3×15 mm², focal length being 305mm, the surface of the material quality can meet the requirements of industrial production, laser surface quenched layer becomes harder, good abrasion resistance on the surface of the material is obtained.

Abstract: This article analyzes the common defects of centrifugal pouring for copper-lead alloy bearing shell, studies the craftwork of centrifugal pouring, discusses the control of pouring temperature, the choice of pouring speed, the control of cooling speed. The research has achieved great results, and effectively reduced the generation of defects.

Abstract: The effects of heat treatment on microstructure and mechanical properties of AISI 4140 for base cutter cane harvester were studied. The effect of heat treatment - i.e. the different quenching medium (water, oil and air mediums) and the different heat treatment condition (quenching, quenching+tempering, cover scrap cast iron+ quenching and cover scrap cast iron+ quenching+tempering) on the on microstructure and mechanical properties (hardness, impact toughness and bend test). The material AISI 4140 was purchased from local market in Thailand and an emission spectroscopy was applied to quantify the amount of elements in steel. The specimens were heat treated in an induction furnace. The resultant microstructure of materials AISI 4140 consists of martensite and retained austenite after quenching all mediums, which quenching in water it have more than in oil and air medium respectively. The microstructure of materials AISI 4140 after tempering process consists of bainitic structure (ferrite and epsilon carbide) and retained austenite, which tempering in water quenching condition it have more than in oil and air quenching condition respectively. The hardness, impact toughness and bended test are according to behavior heat transfer of quenching mediums. The material alloy steel grade AISI 4140 is the good candidates to promote the quenching in water ,oil and air medium and must be continuous to tempering process. The technique heating by cover scrape cast iron it was good for protected surface and decreased decarburization on surface of steels. But it is not necessary for control microstructure and mechanical properties.