What is Tungsten Carbide?
Tungsten carbide is a sintered material that is made up of tungsten carbide particles that are cemented together with a binder metal, most commonly with Cobalt (Co) or Nickel (Ni). Originally it was called Hartmetall by its discoverers, the Osram Lamp Company, but has other names such as Wolfram Carbide (WC) and cemented carbide, but today, basically "Carbide" is used to describe this material.
Tungsten carbide has been utilized since the 1920s as a replacement for tool steels in extreme wear applications. Its properties allow this amazing material to resist some of the harshest working conditions including corrosive environments, high temperatures, extreme compressive loads, high impact as well as severely abrasive wear conditions.
How are Tungsten Carbide parts made?
Before a finished tool or component can be made, typically a blank needs to be made. This is performed through a powder metallurgy and sintering process.
- Firstly a mould of the macro shape of the blank desired is made. This is made intentionally at a calculated larger size to accommodate the volumetric shrinkage (which can approach up to 50%) that will occur later in the sintering process.
- Powders are then prepared with an involved process of mixing and milling, paying attention to particle size and consistency, purity, quantity etc. This step has a significant effect on the “quality” of the overall blank produced.
- The prepared powders are then compacted into a solid “green” state blank with the use of high pressure press. The green blank can then be handled and to some degree additional processes such as turning, drilling and milling can be performed on the item before it is sintered.
- The green parts are then put through a process of pre-sintering, sintering and Hot Isostatic Pressing (if specified) to remove the binder waxes, liquefy the binder and fully densify the cemented carbide. Shrinkage occurs during this process.
- The fully dense tungsten carbide blank may then be further finished by grinding, EDM wire cutting, or diamond polishing. For the most demanding high volume and hardest working production tools, tungsten carbide is a superior base material.
Important Considerations for Carbide
As carbide is made up of WC particles and Co, the relativie contents and size (and addition alloying elements) provide specific properties to the carbide. In general:
- a higher Co content increases the toughness, but lowers the wear resistance
- the larger the WC grain size, the higher the abrsive wear resistance and the more resistant the carbide is to fracture
- The WC size can range from nano scale (<0.2 µm) to extra coarse (> 6 µm).
Coating of Carbide
Various coatings are harder thand carbide and can further improve the wear resistance in metalforming applications: These coatings are:
- TD – at 90 HRC and a pure vanadium carbide it shows improved resistance to galling and the carbide base is very stable during heat treatment. Carbide with Co > 10% can be TD coated
- NANO – The TiAlN is ~ 90 HRC and also shows improved adhesion resistance but the bonding strength is not as hgih as with TD. Any carbide grade can be NANO coated.
What can we do for you?
We can supply in most grades with Cobalt or Nickel binder and Hip Sintering can be performed on request.
Our applications focus on precision cold and hot work tooling as well as high wear parts such as valve and seat components for mining pumps.
Carbide drills, milling tools and turning inserts as well as other high speed spindle tools are NOT our focus, however we ARE able to assist with custom items, raw and semi-finished inserts. Please enquire about your need.
We specialize in fast delivery of fully ground custom components to the tightest tolerances and specifications, but we can also supply near net shape, as sintered blanks to customers that wish to perform their own grinding and finishing. Typical lead times are 3-5 weeks depending on volumes for finish ground items from stock blanks kept by our manufacturers. For custom, as sintered blanks, a tooling period precedes the production of the blanks so 2-4 weeks additional may be required.
We can match most grades of tungsten carbide from other suppliers from coarse grain, high cobalt content, to nano-grain grades with HIP sintering.
Please contact our manufacturing department to request a quotation or to discuss your specific application.
Please mail us to enquire at firstname.lastname@example.org
See below for examples of the range of items made in the past:
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