Laser sintering of tungsten carbide cutter shafts with integrated cooling channels (original) (raw)
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Investigation on Additive Manufacturing of tungsten carbide-cobalt by Selective Laser Melting
The production of special interior contoured tools made of cemented carbide is a time-and cost-intensive multistage sintering process. An alternative for economic, flexible and automated production is provided by a laser-based, additive manufacturing Selective Laser Melting process (SLM). In a shortened process chain near-net-shape and special interior contoured tools can be manufactured energy-and resource-efficiently in small batch sizes. An increase of the tool life is achieved by the use of wear resistant and tough cemented carbide material. This paper focusses on the process behavior of the agglomerated and pre-sintered tungsten carbide-cobalt (WC-Co) powder material in the SLM process. Depending on the exposure parameters, various types of micro structures can be generated and the original material profile can be significantly changed during the laser material interaction.
Characteristics of single layer Selective Laser Melted tool grade cemented tungsten carbide
COMA Proceedings, 2016
Cemented carbide tools, specifically tungsten carbide based alloys, have found a wide range of application fields including manufacturing, agriculture, and mining, among others. A need for customised tooling solutions using cemented carbide alloys have been identified. Additive manufacturing is chosen as a novel manufacturing process due to its superior material and process flexibility. The study investigates the melting behaviour observable during the SLM process using a tool grade cemented tungsten carbide powder. The laser power, scan velocity, and hatch spacing of the SLM process are varied and single powder layers are sintered accordingly. This is done to determine the varying influence these parameter combinations have on the melting behaviour of the material during sintering. For each set of parameter combinations the test samples were analysed using microscopic imaging. It is found that a combination of high laser power, high hatch spacing, and low scan speed yields the best results.
Advances in Science and Technology Research Journal
Precision milling of free (curved) surfaces with the use of monolithic milling cutters is used in the production of hardened steel elements such as dies, molds, or press tools. Precision milling processes are carried out with the following milling parameters: axial cutting depth ap <0.3 mm, cutting width ae <0.5 mm and the required machining accuracy below 40 µm. The quality of the obtained surfaces in injection molds is directly transferred to the quality of the molded part. One of the key criteria for the manufactured elements is the surface quality which is mainly assessed by the roughness parameters. Due to the use of carbide tools high reliability and quality of machining is obtained which allows to eliminate the grinding process. In precision milling processes, due to the very small radius of the cutting edge and the cross-sections of the cutting layers, the conditions that must be met for the decohesion process to occur are fundamentally diff erent from macro-scale. The minimum value range of ap and ae parameters was determined in a carried-out experiment, which allows for stable and repeatable machining. The tests were carried out with double-edge shank cutters with a diameter of 6 mm on a workpiece made out of WCVL hardened steel 45-47 HRC. Recommended machining conditions have been defi ned to ensure the required technological quality of the surface layer. The research was fi nanced under the research project POIR.01.01.01-00-0890/17 co-fi nanced by the European Union from the European Regional Development Fund.
2004
Distortion during sintering has been a critical problem in the fabrication of hard materials such as tungsten carbide by the conventional press and sinter process. Until now, cures for the distortion problem have included changes in the polymer additives, tool motion, and various sintering tricks. This paper shows the sources of distortion can be modeled via computer simulation. As a consequence, we backcalculate the die shape to obtain precise final shapes. In this study, the simulation results by PMsolver (CAE design associated with the conventional P/M process) are verified. The compaction schedule is designed to obtain as uniform a green density distribution as possible and the effect of loading schedule on distortion during sintering are compared to experimental results.
Material Extrusion to Manufacture Carbide-Based Advanced Cutting Tools
Materials
Material extrusion (MEX) allows for the production of advanced cutting tools with new internal cooling systems, which are suitable for new machining equipment. To produce cutting tools via this process, hardmetal and cermet feedstock must be prepared for the extrusion of 3D printing filaments. After shaping the 3D object (green), debinding and sintering must be performed to achieve densification. Defects and microstructural heterogeneities were studied according to the powder material. The present study shows that, although MEX is a viable solution for hardmetals, it needs to produce homogeneous filaments for cermets. The WC-Co bulk microstructures versus hardness were similar to the ones that were measured with pressing and sintering. While cermet (Ti(CN)/WC-Ni/Co) microstructures were heterogeneous, their hardness, when compared with that from the pressing and sintering manufacturing process, decreased significantly.
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This work aims to investigate the technical feasibility of using sintered carbides based on NbC-Ni substitute of the WC-Co class, adding the Sinter-Hip step in the sintering process, with 20 bar pressure nitrogen gas. The samples were produced investigating two process variables: sintering cycles and chemical composition. The samples were qualified in terms of Vickers hardness, toughness and density by Archimedes. The machining experiments were carried out on quenched and tempered AISI 4340 steel material. Flank wear progression was defined as the control parameter, analyzing wear via CCD camera, stereoscopic magnifying glass and SEM/EDS. The best result obtained the binding phase content 10%w, when compared to a commercial WC-Co insert. It showed superior performance at 88% of the average life of the cutting edge. However, the dispersion of this lifetime was higher than the WC-Co reference tool, 15%. The samples of NbC-10%p Ni showed a higher level of porosity than WC-Co. For bette...
Laser treatment of cemented carbide cutting tool
Journal of Materials Processing Technology, 2007
Cemented carbide tools are widely used in machining industry due to their superior properties. Laser processing of the tool surface provides thermal integration of binding agent with carbide compounds in the surface region. This in turn improves the microstructure in the region irradiated by the laser beam. In the present study, laser heating of cemented carbide tool surface is carried out. Temperature field in the irradiated region is obtained and temperature gradients as well as cooling rates in the surface region are predicted. Microstructural analysis prior and after the laser heated surface carried out. Fracture toughness of the laser treated surface is measured using indentation tests. It is found that Co and TaC melt in the early heating period due to their relatively lower thermal conductivity than WC. High cooling rates and temperature gradients below the surface are responsible for high thermal stresses developed in this region. Multi directional cracks are observed at the surface and formation of tungsten nitride (WN) occurs in the surface region as illustrated by XRD measurements.
Direct Selective Laser Sintering of Hard Metal Powders: Experimental Study and Simulation
The International Journal of Advanced Manufacturing Technology, 2002
Direct selective laser sintering (SLS) technology can be used to produce 3D hard metal functional parts from commercial available powders. Unlike conventional sintering, it does not require dedicated tools, such as dies. Hence, total production time and cost can be reduced. The large shape freedom offered by such a process makes the use of, for example, sintered carbides components viable in domains where they were not applied before. Successful results have been obtained in the production of sintered carbide or hard metal parts through SLS. The investigation focuses on tungsten carbide-cobalt (WC-Co) powder mixture. This material is characterised by its high mechanical properties and its high wear resistance and is widely used in the field of cutting tools. This paper is devoted to the experimental study and the simulation of direct selective laser sintering of WC-Co hard metal powders.
International Journal of Refractory Metals and Hard Materials, 2018
The effects of spark plasma sintering (SPS), NbC as a major carbide phase and Ni as a Co binder substitute on the microstructure, mechanical properties and cutting insert wear during facemilling of grey cast iron (GCI) BS1452, grade 17, were investigated. Spark plasma sintering refined microstructures increasing the hardness, but lowered the fracture toughness, due to poor binder distribution. Both SPS and liquid phase sintered (LPS) WC based samples had higher hardness than all the NbC based samples. Substitution of Co with Ni in the NbC cemented carbides significantly increased the fracture toughness (by ~ 5.5 MPa.m 1/2). During face-milling using inserts produced from the NbC and WC based cemented carbides, the cutting speed (v c) was varied between 100-300 m/min and the depth of cuts (a p) between 0.5-1 mm. Face-milling was done under dry and minimum quantity lubrication (MQL) conditions. Wear was evaluated by optical microscopy and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The spark plasma sintered NbC 1.0-12Co (wt%) insert had lower flank wear rates than the SPS and LPS WC-0.8Cr 3 C 2-12Co inserts in all machining tests, due to the combination of good chemical stability, attrition and abrasion wear resistance from the refined microstructure. The lower flank wear rate was also attributed to the shorter chamfer width. Use of MQL at a v c of 300 m/min and a p of 0.5 mm, reduced the cutting temperatures, but increased the cutting force and flank wear rates of all the inserts.