Materials Science Forum Vols. 800-801

Abstract: Summarized the research and development of high speed machining of SiCp/Al composites. Emphasized the research status of high speed cutting of SiCp/Al composite materials, including machined surface quality and tool wear condition. Machined surface quality contains surface roughness and surface defects. The tool wear conditions are different because of different types of cutting tools, but the wear of the rake face, the rear face and the cutting edge are all involved.

Abstract: High speed machining of the corner of hardened steel mould has a great influence to the entire product performance of the mould. In this paper, with the single factor experiments, the influence of feed per tooth, cutting speed and angle of the corner to the cutting forces, the vibration value and the surface roughness were analyzed. And the cutting parameters were optimized. The cutting forces, vibration value and surface roughness value of the corner of the mould reached the minimum value when the cutting speed was 80 m/min and the feed per tooth was 0.006 mm/z in the experiment. The surface quality of corner with angle of 90^o was better than the corner with angle of 60^o and 120^o with various milling parameters.

Abstract: In order to investigate the influence of milling velocity on surface roughness of the cutting entrance, middle part and cutting exit, high milling experiment for the thin walled test-piece of high volume fraction SiCp/Al composites was preformed with PCD tool. The results indicate that when milling at lower speed 60m/min, the SiCp/Al test-piece is apt to vibrate. As well as, the surface roughness machined test-piece in cutting exit increases obviously and its Ra value reaches 1.721μm, which leads to the inferior surface quality. In conclusion, the surface roughness, either at cutting entrance, middle or at cutting exit, all is a decline trend with the milling speed increasing. Moreover, Ra value of the cutting entrance is the biggest, followed by the middle, and the cutting exit is the smallest.

Abstract: This paper presents a study on the tool wear of micro PCD end mill when machining ZrO₂ ceramics. The cutting tool used was a self-designed PCD micro end mill with 1 mm in diameter and single flute. Experiments were conducted on a self-developed micro-milling machine tool. The tool wear characters and progress during the groove milling has been observed. The cutting force and machining accuracy of the grooves also have been studied. Based on the results, it is found that tool wear is mainly on the bottom surface; the cutting force increases with the progress of tool wear; tool wear also affect the width of machined grooves due to the decrease of effective tool diameter.

Abstract: The laser solid forming (LSF) TC4 (Ti6Al4V) alloy is made throughmelting the raw material powder layer by layer with impulse laser beam. The mostrecent advancement of the LSF TC4 alloy exhibits comparable mechanical propertieswith conventional forging TC4 alloy, which enables wider application in the fabrication of structural components in the aerospace industry. However, the accuracy of the LSF process is limited to only about tens of microns due to the laser system,machining is still necessary for the application of LSF TC4 in precision conditions. In this paper, the machinabilities of LSF TC4 and forging TC4 are studied through the turning experiments. In addition, the signature analysis of the cutting force signal is carried out to correlate the anisotropic property of the LSF TC4 with the cutting force dynamic characteristics.

Abstract: Compacted graphite iron (CGI) has excellent comprehensive performance of strength, hardness, abrasion resistance, shock absorption and thermal conductivity as an ideal material for making engine parts. The material performance of CGI is compared with that of gray iron (GI) and spheroidal graphite Iron (SGI). Some research shows that the strong adhesion between the iron and the graphite forms semi-continuous chips when machining CGI which requires more energy than GI cutting, and there's no MnS layer on the cutting edge during CGI cutting. Thus, the cutting tool life of CGI is greatly reduced than GI. The experiment results indicate that the cutting forces of CGI milling are much higher than that of GI when the feed and the depth of cut increase.

Abstract: The oxide film on implant surface of biomedical titanium alloy is crucial to its bioactivity and biocompatibility in human body. A new method is proposed to obtain titanium oxide film by cutting process in oxygen-enriched atmosphere. A gas mixing system is firstly developed to provide oxygen-argon mixed gas to the flank face of insert during turning. The results show that oxygen-enriched atmosphere promote the oxidation reaction of titanium element. Thicker oxide film can be obtained in oxygen-enriched condition than that in natural atmosphere. The corrosion resistance is also improved significantly by this method in electrochemical test.

Abstract: Experiments were carried out to investigate the cutting force and tool wear behavior of Sialon ceramic tools in high speed milling of GH4169 under different cutting parameters. The cutting speed exhibited the most significant influence on the cutting force. The cutting force decreased firstly then increased with the increasing of cutting speed. And the effect of feed speed and cutting depth on cutting force were also discussed. The worn surfaces of tool were examined and the elements on the tool surfaces were analyzed by employing scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), respectively. The analysis results of the SEM and EDS showed that the dominant wear pattern were rake face flaking and notching at the low cutting speed while flank wear was the main wear type at the high cutting speed of 1037m/min.

Abstract: Lots of hole machining in CFRP(carbon fiber reinforced plastics) are conducted in the astronautic fields, especially a large size hole machining. The purpose of this article is to investigate the optimal cutting parameters and allowance distribution in CFRP 18/32inch hole machining by thoroughly considering the cutting forces and burr length. All tests were run without coolant using different drills, expanding drills and reamers. The damage generated and the cutting forces produced in CFRP composites cutting were observed. Therefore, the optimal allowance distribution in CFRP large size hole machining was obtained, providing compound tools design with theoretical direction.