Carbide Production Steps SAAR-HARTMETALL USA LLC

6. Finish machining

If the product does not feature the required shape or
tolerances after sintering, it will be finish-machined by e.g. grinding, turning, drilling or EDM.


Cemented Carbide is the general name for a type of material with a distinctively high hardness and metallic properties. The more restricted meaning of cemented carbide is the combination of metallic hard particles with relatively soft and tough metals, especially cobalt and nickel, the so-called binders or binding metals. The quantatively higher hard particles are cemented by the interposing layers of the binding metal, just like the aggregates in concrete are cemented by cement.	For this reason the English terminology refers to hard metals as “cemented carbides”. Cemented carbides combine the high hardness of the metallic hard material with the toughness of the binding metal. The combination of binder, hard material and grain size achieves a multitude of properties thus opening up a wide range of applications for cemented carbides.

1. Weighing-in of the components Depending on the percentage and the particle size of the basic materials different properties like hardness or toughness can be adjusted. The most common basic materials of the cemented carbides are: Tungsten carbide (TC) Cobalt (Co) Tantalum carbide (TaC) Titanium carbide (TiC) Nickel (Ni) and other components
	Addition of a mixing- and milling liquid: Acetone or Alcohol 2. Mixing / Milling in the Attritor Mixing and milling in an attritor is carried out by adding a mixing and milling liquid and takes several hours. During this process agglomerates of the basic materials are destroyed and a homogeneous mix is achieved.

Addition of paraffin to ease granulation and later pressing Homogeneous mixture of the rawmaterials and the mixing liquid.
Ideally the composition of each granular grain corresponds to the ratio of the used basic materials. The most important properties of the granulated powders are good pourability and good compressibility. Single granular grains with a diameter of about 200µm


4. Pressing/Shaping The granulated powders are compacted to near net shapes. If the compacted green features sufficient hardness, it can be machined by grinding, drilling or turning. Moreover its hardness can be slightly increased by means of a heat treatment, presintering, at a low temperature. Vacuum Furnace 5. Sintering Sintering means heat treatment implying a liquid phase, and simultaneous compression. The maximum sintering temperature (1300° to 1550°C) is near or slightly above the melting point of the phase with the lowest melting point Unlike the conventional melting technology used in the steel production, not all components enter the liquid phase. The liquid phase mainly cobalt fills the small spaces and the still solid particles are getting close to each other leading to increased density and volume shrinkage of the green. All this involves complex metallurgical processes of dissolution and segregation. After cooling, there is a microstructure, where the hard Tungsten carbide particles are embedded in a relatively soft cobalt matrix. The product has reached its final density and hardness. Diamond grinding disk

3. Granulation via spray drying

By means of the granulation, the fine particles of the different basic materials are agglomerated to bigger grains.

To achieve this, paraffin is added. After a second homogenisation the “slurry“ is vaporised in small drops via a spray drying process. The drops rise in the spray dryer and hit upon an inverted stream of hot gas. The liquid parts of the mixing and milling agent evaporate and the solid particles agglomerate under the stabilizing effect of the paraffin to globular grains.