Processing of Tungsten Carbide
We present different procedures
Construction parts made of sintered tungsten carbide, such as drawing and forming tools or parts subject to wear, are used today in many areas of mechanical and plant engineering. In order to fulfill a particular component's function, high demands are placed on the shape and surface quality as well as the dimensional accuracy, which cannot be met in the manufacturing process.
During the sintering process, there is a linear shrinkage of the composite of 18-22% as a result of the compression process. The extent and uniformity of the shrinkage are primarily determined by the compression density achieved and its distribution. Other influencing factors include the composition of the carbide mixture and the sintering atmosphere.
Since deviations in shape and dimensions of the raw part from the respective nominal size cannot be avoided, the parts are prefabricated with sufficient allowance and reworked after sintering to produce high-quality functional surfaces.
Due to the high hardness of the materials, only a few manufacturing processes are available for reworking sintered carbide. Essentially, cutting processes with a geometrically indeterminate cutting edge such as grinding, honing and lapping, polishing and abrasive processes such as spark erosion and laser machining are used for machining.
The processing of the extremely hard materials is very cost-intensive due to the low removal rates and the high tool wear, and often determines the economic efficiency of the use of hard metal components.
With regard to the achievable removal rates and the surface qualities and shapes that can be produced, grinding is currently the most important manufacturing process for machining tungsten carbide.
A definition of the grinding process is given in DIN 8589, Part 11 (4). Grinding with rotating tools is a cutting production process with multi-edged tools, whose geometrically indeterminate cutting edges are formed by a large number of bound hard material particles and which cut the material at high speed, usually with non-constant contact between the workpiece and the abrasive grain. At this point it should be noted that the word "grain" in this context is to be understood as a polycrystalline hard material particle.