The Production Process of Tungsten Carbide
What is tungsten carbide?
Tungsten carbide, or cemented carbide, which is also called a hard alloy, is recognized as one of the hardest materials in the world. Actually, it is a metal, but a combination of tungsten, cobalt, and some other metals. The highest hardness tungsten carbide made right now is around 94 HRA, measured by Rockwell A method. One of the most important compositions of tungsten carbide is tungsten, which has the highest melting point among all metals. Cobalt acts as a binder in this metal matrix and improves the bending strength of tungsten carbide. Because of the high performance of tungsten carbide, it is a perfect material for many industries, such as tungsten carbide inserts, carbide rods and end mills for CNC cutting tools; cutting blades for paper cutting, cardboard cutting, etc; tungsten carbide heading dies, nail dies, drawing dies for wear resistance application; tungsten carbide saw tips, carbide plates, carbide strips for cutting and wear application; tungsten carbide buttons, HPGR studs, carbide mining inserts for drilling fields. Tungsten carbide material is so widely used so it is also called “the teeth for industries”.
What is the production process for tungsten carbide?
1. The first step to making a tungsten carbide product, is to make the powder. The powder is a mixing of WC and Cobalt, they are mixed together in a certain ratio. For example, if the customers require tungsten carbide heading dies, want carbide grade YG20, quantity 100 kilos. Then the powder maker will mix around 18kgs Cobalt powder with 80kgs WC powder, the balance of 2kgs are other metal powders that will be added in according to the company recipe for YG20 grade. All the powders will be put into the milling machines. There are different capacities of milling machines, such as 5kgs for samples, 25kgs, 50kgs, 100kgs, or bigger ones.
2. After powder mixing, the next step is spraying and drying. In Zhuzhou Better Tungsten Carbide Company, a spray tower is used, which will improve the physical and chemical performance of tungsten carbide powder. Powder made with Spray tower has much better performance than other machines. After finishing this process, the powder is in “ready-to-press” condition.
3. The powder will be pressed after the “ready-to-press” powder is tested OK. There are different ways of pressing, or we say different forming ways of the tungsten carbide products. For example, if a factory produces tungsten carbide saw tips, an auto-press machine will be used; if a big tungsten carbide die is required, a half-manual pressing machine will be used. There are also other ways of forming the tungsten carbide products, like cold isostatic pressing(short name is CIP), and extrusion machines.
4. Sintering is the process after pressing, it is also the last process to produce a tungsten carbide metal which can be used as high hardness and high strength engineering metal for cutting, wear-resisting, drilling, or other applications. The temperature of sintering is high to 1400 centigrade. For different compositions, the temperature will have some differences. At such a high temperature, the binder can combine the WC powder and form a strong structure. The sintering process can be done with or without a high isostatic gas pressure machine(HIP).
The above process is a simple description of the cemented carbide production process. Though looks simple, tungsten carbide production is a high-tech gathering industry. It is not easy to produce qualified tungsten carbide products. Tungsten is a kind of non-renewable resource, once used, it is not possible to form again in a short time. Cherish the valuable resource, make sure every batch of tungsten carbide products is qualified before reach to hands of customers, is one of the key reasons pushing us to do better. Keep moving, keep improving!