Papers by Keyword: Diamond Tool

Abstract: This paper performed a series of experimental investigations for typical die steels with ultrasonic vibration assisted turning. The micro-morphology of rake face and flank face of diamond was detected by scanning electron microscopy, and the roughness of machined surface was measured by Form Talysurf. In order to clarify the influence laws of cutting parameters and tool geometric parameters on tool wear and surface quality. The results revealed that the wear of diamond and surface roughness rely heavily on the feed rate, and have less relativity with the relief angle and the depth of cut to an extent. In addition, the function mechanism of ultrasonic vibration turning had been analyzed, it exhibited that this technological measure has enhanced tool life and improved surface quality to a large extent.

Abstract: The work attempts substitution of very expensive, wear resistant Co-WC powders, that are commonly used in the production of sintered diamond tools, with cheap iron-base counterparts manufactured by ball milling. It has been shown that ball milled Fe-Ni and Fe-Mn powders can be consolidated to a virtually pore-free condition by hot pressing at 900°C. The as-consolidated materials are characterised by high hardness and resistance to 3-body abrasion.

Abstract: The problem of diamond tool wear is the bottleneck for machining large metal reflector with ultraprecision cutting method. In this paper, the author performed simulation study on diamond tool wear in machining large metal reflectors, and established a molecular dynamics simulation model for dynamic simulation of tool wear; and found that in the simulation process the change in cutting speed and cutting depth had definite effect on the tool wear, and the main factors affecting the tool wear was the cutting distance.

Abstract: This paper introduced a kind of fast tool servo (FTS) that its stiffness is adjustable. Based on in the frame rack, flexible hinge, piezoelectric ceramic driver, tool base, diamond tools and so on, a spring assembly appendixes on. The spring assembly is consisting of spring rack, the sleeve, spring, and lock circle etc. Spring rack is fixed in front of the frame rack; there is a screw hole in the middle of the spring rack; there is also a screw outer side of the sleeve that mounted through the screw hole. The spring is installed inside sleeve; one end of the spring contacts with the bottom of the sleeve, and the other end contacts with the flexible hinge on frame rack. It can adjust the force of the spring that presses to the flexible hinge by rotating the sleeve. Through replaced the spring, it can makes stiffness of the FTS changed. It is verified that the device has the stiffness adjustable function through calculation and simulation.

Abstract: Titanium alloys, as difficult-to-cut materials, have poor machinability due to their superior mechanical properties, heat resistance and corrosion resistance. High cutting temperature and great cutting force that will greatly accelerate tool wear often occurs in titanium alloys cutting process. In this paper, an ultrasonic vibration turning method was used to lower diamond tool wear during TC4 titanium alloy turning process. Ultrasonic vibration turning tests were carried out with various cutting parameters. Experimental results indicated that there’s a significant reduction of the wear rate of diamond tools by means of ultrasonic vibration in TC4 turning process. For ultrasonic vibration turning, spindle speed, the amplitude and frequency of vibration of the tool are the greatest impact of tool wear, followed by feed rate, then the cutting depth.

Abstract: Single-phase (binder-less) nano-polycrystalline diamond (NPD) has been synthesized by direct conversion sintering from graphite under high pressure and high temperature. NPD is characterized by extremely high hardness compared with single crystal diamond (SCD), even at high temperature. In addition, NPD has high wear resistance, no anisotropic mechanical properties, no cleavages, and high thermal stability. These characteristics suggest that NPD has high potential for use in precision cutting tools for various hard works. In order to evaluate the cutting performance of NPD, cutting tests for various cemented carbides were conducted under various conditions and the results compared with those of single crystal diamond (SCD) and conventional polycrystalline diamond containing metal binder (PCD). The results revealed that NPD has outstanding potential for precision cutting and processing of diverse hard and brittle materials.

Abstract: Micro V-groove cutting of cobalt-free tungsten carbide using two types of V-shaped diamond tools is performed using mist of zinc dialkyl-dithiophosphate (ZnDDP) as lubricant. The two types of tool tested are 1) mono-crystalline diamond and 2) poly-crystalline diamond made of approximately 30 nm-sized diamond crystals. The geometry of the V-groove-cutting process is theoretically investigated and the relationship between V-groove angle, original rake angle, and effective rake angle is clarified. Through the cutting experiments, the effects of diamond types and rake angle on tool-wear characteristics are explained. When rake angle is set at zero degrees, tool chipping frequently occurs for both types of diamond tools even when ZnDDP is supplied. However, when rake angle is set at -30 degrees for poly-crystalline diamond, tool wear is minimized.

Abstract: This paper deals with a new surface finishing method of electrically conductive diamond materials by making efficient use of an electrically conductive nature of the workpiece material, instead of conventional methods such as grinding, lapping and polishing using diamond abrasives. The authors focused on the electrolytic machining method and not on the electro discharge machining method for the two advantageous features of the electrolytic machining in addition to the general view that a better surface roughness could be obtained. One of those features is that no higher heat is generated at the machining point. This can eliminate a risk of the film delamination in the case where a workpiece is the CVD diamond coated tool. The other is that a wider machining gap is available between an electrode and a workpiece. This was thought to allow the electrolytic machining to be applied to a tool with a complex shape such as a drill and an endmill. Based on these concepts, electrolytic machining experiments were conducted on the electrically conductive diamond materials. From the results, it was found that the surface of the electrically conductive diamond could be smoothened enough by electrolytic machining though relatively long period of time was required.

Abstract: Non-oxide covalent ceramics such as TiC and TiN display hardness and thermal stability that favor their use as cermet insert for high speed turning operations. The objective of this work was to assess the properties of the TiC combined with W-Mo as binding matrix. The cermet sintering was carried out inside a toroidal anvil type of high pressure device up to 1.0 GPa of pressure and temperatures up to 1800°C. It was found that at 1400°C the Mo reacts with TiC forming Mo₂C while at 1800°C the reaction with W forms WC. Moreover, the cermets density reaches 98% of the theoretically calculated value with strength of 942 MPa and Rockwell A hardness of 94. Efficient turning parameters are reported for machining operation using these cermets as tools insert.

Abstract: Some diamond tools use iron in their composition, and it is known that iron is a strong catalyst for the graphitization of diamonds. This graphitization occurs mainly during the processing of composite materials - conventional sintering or hot pressing, and during cutting operations. This work studies the influence of the behavior of the wear and adhesion, of iron-diamond composites, by considering the use of TiC coated diamonds. Samples were prepared by mixing powders of Fe (40 μm) and diamond (425 μm), and subsequent hot pressing at 35MPa/900°C, for a time of 3 minutes. It was evaluated the mechanism of wear, and the behavior of the samples during diametral compression test. It was used the cumulative times of 2, 6, 12 and 20 minutes during the testing of abrasion.