Investigation on Wear Characteristics of Cemented Carbide Tools in Finish Turning Spherical Shells of Pure Iron

A thin-walled spherical shell made of pure iron material is a key part of precision physical experiments. Tool wear is an important factor restricting its geometric accuracy. And tool wear characteristics of curved surface parts are significantly different from those of single-point turning due to the movement of the contact point between the tool and the workpiece. Hence, this article takes the pure iron spherical shell as the research object, which is aimed at investigating the formation mechanisms of flank wear land. Tool wear characteristics are compared between spherical shell turning and end face turning. The results show that uniform flank wear land and notable notch wear occur when turning end face, but notch wear disappears and only flank wear land exists when turning spherical shell. Based on major notch position and minor notch position, a mathematical model is developed to explain formation mechanisms of flank wear land during turning spherical shell of pure iron materials. Theoretical and experimental results show that flank wear land results from the major and minor notch movement. Spherical shell turning and end face turning have the same wear mechanisms, mainly composed of adhesive wear, diffusion wear and oxidation wear.

Development of Si3N4/(W,Ti)C/Co Graded Nano-Composite Ceramic Tool and its Performance in Turning GH2132 Alloy

Strength and fracture toughness of ceramic tool materials can be enhanced by adding ductile phases. However, the hardness will be decreased, which is undesirable especially for cutting tool materials. Combining with functionally gradient materials (FGMs), the mechanical properties can be tailored so as to achieve high hardness at the outside of the ceramic materials leaving a relatively tough core inside. In this paper, a Si3N4/(W, Ti)C/Co graded composite ceramic tool material was fabricated by hot pressing technique. The composites without Co were used as the surface layers and the composites containing Co were used as the inner layers. Subsequently, the cutting performance of the graded ceramic cutting tool in turning iron-based high temperature alloy GH2132 was studied in comparison with common reference tool. The cutting forces, cutting temperature, tool wear modes and failure mechanisms were discussed. Results revealed that the resultant cutting forces firstly decrease and then increase with the increase of cutting speed, while the maximum cutting temperature increases gradually. Tool live of the FGM tool exceeds that of the corresponding common ceramic tool with the same composition systems. Formation of the residual compressive stress in the surface layer induced by the graded structure contributed to the longer tool life. The main failure modes of the FGM tool were adhesion, groove wear on the rake face and notch wear on the flank face. The graded tool shows better notch wear resistance than the common reference tool.

Wear Analysis of ZTA-MgO Ceramic Cutting Inserts on Stainless Steel 316L Machining

The performance of zirconia toughened alumina with addition of MgO additives is investigated. Optimized composition of MgO at 1.1 wt% was used in the composition with alumina/yittria stabilized zirconia (YSZ). The composition was mixed, uniaxially pressed into rhombic 80o cutting inserts with 0.8 mm nose radius and sintered at 1600oC for 4 h in pressureless condition. For machining analysis, commercial stainless steel 316L with 12 mm diameter were used as workpiece. The workpiece was machined at 625 to 1750 rpm. Tool wear and surface roughness of workpiece were measured. Result shows three types of wear behaviour appear which are flank wear, notch wear and chipping. Flank wear and notch wear increased with the cutting speed but decrease by increasing the feedrate before increased after passing the 0.2mm/rev feedrate. While chipping very much related to the feedrate as the chipping area increased when the feedrate increased. Meanwhile, surface roughness increase with increment of cutting speed and feedrate which match the wear pattern.

Research on the Cutting Property of Ceramic Tool Cutting Nickel Based Superalloy GH4169

This paper will use the Al2O3-SiCw whisker toughening ceramic tool WG300 and Si3N4-Al2O3 (Sialon) SX9 ceramic tool cutting performance test.Study on different cutting speed, ceramic cutting tool in machining nickel based high-temperature alloy tool life and tool wear mechanism, and analysis of the wear form under different cutting parameters. The test results show that: with the increase of the cutting speed, WG300 and SX9 two kinds of tool durability showed a downward trend, the value of VB is higher than that of Al2O3-SiCw whisker reinforced ceramic cutting tool flank wear of Sialon ceramic cutting tool, but its notch wear value VN is far less than Al2O3-SiCw whisker reinforced ceramic cutting tool,the main failure form of WG300 notch wear, the main failure form of SX9 for the flank wear.