What PCD Will Not Do:

PCD is not recommended for the machining of Iron, Cobalt, or Nickel alloys. In the presence of these metals and the heat and pressure created by cutting, diamond is encouraged to revert to the metastablecarbon form: graphite.

It is possible to machine some stainless steels and other highly alloyed materials,which have the iron, cobalt or nickel tied up in a non-reactive state. Even so, these materials should be machined at low cutting speeds with coolant to reduce any heat generated.

PCD contains a small amount of Cobalt as a result of the manufacturing process. If a PCD tool is subjected continuous and significant heating during cutting, the diamond is likely to transform back to graphite. In order to avoid this effect, the use of coolant is recommended.

Due to the polycrystalline nature of PCD, it is impossible to create cutting edges as perfect as those of single crystal diamond. Even with the finest grade PCD, which has a particle size of 2 microns, it is not possible to machine plastics and produce optically flat surfaces.

PCD tools are relatively expensive, compared with conventional cutting tools. Poor quality materials, which have inclusions that break conventional cutting tools, or work holding systems that do not locate and hold the part securely, are likely to have the same effect on PCD tools but at a greater cost.

Metal matrix composite (MMC) materials, Aluminium reinforced with Silicon carbide particles or filaments can be machined with PCD, but as the SiC content increases the tool life reduces and materials with more than 30% SiC are practically impossible to machine other than by grinding or EDM.

David Richards stock a range of I.S.O. standard cutting tool inserts. The cutting geometry of these tools is ideal for machining the most common materials; Si/Al alloy, copper, brass and abrasive plastics.

For MMC, very high silicon content alloys and other more specialised applications, different geometries are available, many ex-stock, to enable the tools to achieve the best performance.