Rieter

The ring material

Index

The ring should be tough on the inside and hard on the outside. Very close attention should be paid to the running surface in particular in this respect. Uniformly high hardness of the boundary layer of about 800-850 HV is required. A lower hardness (650-700 HV) should be chosen for the  traveler, so that the traveler, which is less expensive and easier to replace, wears rather than the ring. Surface smoothness is also important. It should be high, but not too high, otherwise a lubricating film cannot form.

The following materials are used:

  • case hardening steel in some cases
  • nitride steel
  • ball bearing steel; this is currently the customary ring material.

However, modern rings usually feature a surface coating.
The object of such coatings is

  • to reduce friction,
  • to reduce wear,
  • to prevent corrosion and
  • to simplify running-in the ring

Coatings used include:

  • oxides
  • nitriding
  • carbonitriding
  • hard chrome
  • nickel (in some cases containing hard particles)
  • ceramics