Papers by Keyword: Hardened Steel

Abstract: This paper reports the development of a cutting tool insert prepared by consolidation, followed by Spark Plasma Sintering (SPS) of TiB₂ (Titanium diboride) particles processed through an in-situ reaction and AlN (Aluminium nitride) manufactured by the direct nitridation process. In-situ TiB₂ particles, formed during reaction of KBF₄ (Potassium tetra Fluoroborate) and K₂TiF₆ (Potassium Fuorotitanate) with Al alloy, are obtained by dissolving the Al-TiB₂ composite in an acidic medium. The extracted TiB₂ (30%) particles are blended with AlN and Al₂O₃ in the weight ratio of 67%-3% and sintered (SPS) at 1440°C with a compaction load of 50 MPa and a total sintering time of 8 minutes. The sintering is carried out in vacuum. The sintered ceramic displays high hardness of nearly 15.5 GPa and extraordinary toughness of 7MPa.m^1/2. The inserts are manufactured according to SNGN (Square Double-sided ceramic) configuration. To study its performance, machining is carried out on hardened steel (EN 24). The developed AlN based inserts show increased wear resistance and provide good surface finish when compared with commercially available ceramic inserts (70%Al₂O₃+30%TiC). Cutting forces are recorded with a Kistler® dynamometer to correlate them with the tool wear. Methods of preparation and comparison of wear resistance and surface finish of the machined material with those pertaining to commercial ceramic inserts are also presented. SEM images are displayed, which support the results.

Abstract: Precision grinding is one of the important processes for finishing of hardened steel parts. However, the grinding process might be quite costly providing the parts with shape complexity should be finished because a number of production steps are needed. Also, this process has some environmental issues, such as disposal of a large amount of grinding sludge and grinding fluid. Precision cutting would become a better alternative process to reduce cost and environmental burden because process steps can be simplified by use of CNC machine tools with PcBN cutting insert if deterioration of cutting tool edge by wear and chipping can be suppressed for long duration. In this study, to improve performance of a PcBN cutting insert, such as wear resistance and defect resistance by the applying of pulse laser processing to sharpen cutting edge in order to realize substitution of cutting for grinding. Precision cutting experiments for hardened steel are conducted by use of the PcBN insert with sharp and tough edges processed by pulsed laser and, for comparison, by use of the PcBN insert ground with diamond wheel. From the results of cutting experiments, it was found that precision cutting with PcBN insert processed by pulsed laser can provide a steady cutting state for a long cutting duration, and a smooth finished surface comparable to precision grindings.

Abstract: The machining of hard turning is performed on hardened steel in the range of 45 to 68 Rockwell hardness using a variety of tool materials such as Polycrystalline cubic boron nitride (PCBN) , Polycrystalline diamond (PCD) and Cubic boron nitride (CBN). It is an alternative to conventional grinding process is a flexible and effective machining process for hardened metals and hence broadly used in various applications such as dies, moulds, tools, gears, cams, shafts, axles, bearings and forgings. Although the process is performed within small depth of cut and feed rates, estimates to reduce machining time as high as 60 % in hard turning. This paper discusses the importance of hard turning of AISI D2 steel. In this study, Experimental investigations are carried out on conventional lathe using prefixed the cutting conditions. The responses studied in the investigation are cutting forces (F_a, F_t and F_z). The cutting parameters considered for the investigation are cutting speed, feed and depth of cut. The influence of machining parameters on response is studied and presented in detail.

Abstract: Burnishing hard materials can be used as an alternative finishing process. This paper presents the results of burnishing hardened steel. The article discusses surface deformation that occurs during this process and depends on the selected parameters of the geometric structure of the force applied for surface burnishing.

Abstract: The surface of the finishing machined parts is defined mainly by roughness parameters. Growing demands on the part, especially mating sliding or rolling, require the specification of additional parameters, such as waviness parameters, particularly when there is significant resistance to seizing or noise reduction. This paper presents surface waviness characteristics of hardened burnished steel.

Abstract: Cutting deformation mechanism of hardened steel has been studied. The influences of the cutting parameter for the chip roots have been researched with single factor testes. The influences of the per tooth feed rate and cutting speed for the shear angle and shear strain also have been obtained by lots of trials, choosing more appropriate axial depth of cut and radial depth of cut.

Abstract: This paper studies the influence of a laser thermal effect on the material. It presents the research of the steel structure under laser irradiation. It explains and demonstrates the structure of steel 5140 after laser treatment. The research method, preparation for the research and material selection are described.

Abstract: The existing safety evaluation of high-speed milling cutter mainly based on ISO15641 standards, which by idling experiments, then analysis and determine centrifugal force conditions what cause permanent deformation and fracture destructive of cutter, this method cannot be forecast and control the dynamic evolution of the milling cutter's safety and reliability, when cutting load changed suddenly.This paper using the high speed milling cutter's failure criteria and safety margin model of cutting hardened steel, analysed and evaluated coupled thermal field distribution caused by hardened steel surface feature that changed frequently and cutter's impact, fatigue, strength, stiffness, safety margin which cuased by mutated shock load of cutter, then forecast safety and reliability of high-speed milling cutter, and proposed the control method of safety and reliability that could milled hardened steel in high speed.

Abstract: Mould surface loading state is one of the most important factors which would affect the mould performance in the course of service. According to the established hardened steel milling surface geometry model, a bending forming numerical simulation of hardened steel milling is conducted, the influence law of service process surface load state is analyzed under machined surface geometry structure which is formed by different milling parameters. The research results show: surface load concentrated area is mainly focusing on mould edge transition and fillet in the course of service; the surface geometry structure has an important influence on the mould service load in the course of service, service load more smaller which is more helpful to improve the mould service performance in the course of service.

Abstract: The service performance is seriously effected by milling machined surface integrity of auto hardened steel mould. Basing on the microscopic damage evolution theory and hardened steel mould material micro-voids cell model, according to the service process load condition of hardened steel milling machined surface, surface microscopic damage evolution analysis had been conducted, surface evolution characteristics was obtained under different shapes void cell. Through comparative analysis the change law of damage evolution internal variable under different shapes void cell can know: respect to the ideal spherical, when the change of void volume fraction and the degree of matrix material yield were considered, the oblate hole more faster and the prolate hole more slower, which provide a further prediction for surface damage.