Recycling carbide tools

The life of a carbide drill bit or cutting tool is measured in fractions of a millimetre, while the tool itself could be over a hundred millimetres long. There is good reason for this, but nevertheless and end-of-life tool retains significant value due to the materials and energy used to produce it. Today, when environmental impact and security of supply are becoming ever more important, the simple message is that used tools must be recycled.

Why so short lived?

This question probably needs little explanation for those involved in machining. The geometry of cutting tools is critical to cutting performance, and small changes due to wear can quickly lead to out of spec dimensions, poor surface finish, or excessive heat or vibration. ISO 3685 is one example of tight limits applied to tool life [1]. In extreme cases, wear can eventually lead to catastrophic tool failure risking damage to the workpiece and the machine.

Why so recyclable?

Some key factors that make a material feasible to recycle include:

  • Is it difficult and expensive to produce in the first place?
  • Can it be readily collected and separated from other materials or contaminants?
  • Can it be readily transported back to producers for reprocessing?
  • Can it be reprocessed to achieve equivalent properties to virgin material?

Carbide tools tick all these boxes.

A typical carbide tool is made of very hard, wear resistant, tungsten carbide particles cemented with metallic cobalt. The exact composition varies between types of tools, but the main raw materials are tungsten followed by cobalt. Obtaining these materials from primary sources is expensive and energy intensive, and often subject to volatile political situations; for example, 68% of the EU’s cobalt comes from the Democratic Republic of the Congo [2]. Both materials are on the EUs critical raw materials list [2].

Carbide tools are dense and compact, meaning a relatively large mass can be transported in a small volume, making return transport for recycling economical. Furthermore, a machine shop is a well-controlled environment from which to collect material with minimal contamination. Finally, economical processes exist to reprocess the materials to high quality product through both mechanical and chemical routes.

Tool producers and scrap traders are eager to buy used carbides and overall recycling rates for tungsten and cobalt are around 42% and 22% respectively [2], which is comparatively good but leaves room for improvement.

Altogether this points to the potential for carbide tools to be a leading example of the circular economy.

[1] International Organisation for Standardisation (1993). Tool-life testing with single-point turning tools. ISO 3685:1993

[2].  "European Commission, Study on the EU’s list of Critical Raw Materials – Final Report (2020)"

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