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 When Not to Use PCD


     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.







David Richards Engineering  2013