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Tuesday, March 3, 2015

Graphitization of Diamond Tools

The diamond is the hardest material in the world. It also has a very high temperature tolerance. This makes it one of the most effective components in cutting tools.

Diamond tools are most widely used in superfinishing, otherwise known as microfinishing. This is a metal working process that improves the surface finish of the work piece. This is done by removing the amorphous layer that is left from previous abrasive processes. Superfinishing  creates a cross-hatch pattern on the workpiece. If performed at high and fine speeds, this can create a mirror-like finish.

Diamond tools, however, are not suitable for cutting steel as this can result to severe wear on the tool. This makes it inefficient and unprofitable .

The severe wear occurs due to graphitization, a process that turns the crystal structure of a diamond into a graphite crystal structure. Carbon steel and alloys with cobalt, nickel and titanium can cause graphitization.

Plenty of efforts have been made in an attempt to make diamond tools viable for cutting steels. One method is to perform the cutting process in specially designed chambers that prevent graphitization.
Since graphitization only happens at temperatures above 200 degrees Celsius. In a cryogenic chamber, a diamond tool can be used for cutting steel without the problem caused by graphitization. The problem with this and other similar methods is that the equipment needed for the setup is quite expensive which is not ideal for many who are running a smaller operations.

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