Papers by Keyword: Cobalt Content

Abstract: Tool life tests of continuous cutting superalloy GH2132 were carried out by WC/Co cemented carbide cutting inserts of different grain size and cobalt content, and flank surface wear morphology of the cutting inserts were observed by ZEISS continuous zoom stereo microscope and microphotograph system. The results show that grain size and cobalt content strongly influence the cutting tool life and tool wear, grain refinement and proper cobalt content are help to improve the tool life and the wear resistance of WC/Co cemented carbide. The wear mechanisms of different grain size and cobalt content of ultrafine cemented carbide tools were adhesion and notch, among them, adhesive was the main wear mechanism at higher cutting speeds.

Abstract: In this study a single step of the chemical pre-treatment is implemented to tungsten carbide (WC 6 [%]) at the surface of the substrate in order to solve poor adhesion problem. During the pre-treatment process, numerous parameters such as etching time, acid temperature and concentration affect on the surface roughness and Cobalt content of WC-Co substrate are investigated. Optimal selection of these parameters is one of the significant issues to achieve high-quality work-piece in etching process. Thus, the statistical model based on nonlinear polynomial equations is developed for the different responses. Non-dominated Sorting Genetic Algorithm (NSGA-II) with the use of MATLAB Software codes is used to solve multi-objective optimization problem in order to provide a preferred solution for a process engineer in a short period of time.

Abstract: In micro drilling, the run-out of drill due to rotational motion error of spindle or eccentric chucking of drill causes machining error and larger radial forces which may break the drill. Furthermore, because the spindle speed is very high, rotating bending fatigue of drill may dominate the tool life. In the previous work, relationship between bending deflection and radial cutting force, and fatigue fracture of drill were investigated theoretically and experimentally. The objective of this paper is to investigate more in detail the relationship between the radial cutting force/deflection of drill and its fatigue life. A series of pseudo rotating bending fatigue tests was performed by using three types of ultrafine grain carbide drill blank with 0.1mm diameter. The main results obtained are as follows, (1) Rotating bending fatigue curve did not depend on cobalt content and tungsten carbide grain size. This differs from the results of conventional cemented carbides. (2) The fatigue fracture surface was dominantly occupied by fast fracture regions.