05:05 Jul-22-2004 Godfrey Hands Engineering, PRI Nadcap, United Kingdom, Joined Nov 1998 283
Re: defects on bearingraceways ----------- Start Original Message ----------- : Hello, : Does anyone have a suggestion where to find criteria for rejection or approval of defects like nicks, dents or scratches on hardened carbonized raceway surfaces. : I already have ANSI B3.2-1992 : thanks : xander ------------ End Original Message ------------
Many bearing manufacturers will have their own specification for acceptance of nicks, dents and scratches on bearing raceways. They keep this information proprietary, so it will be very difficult to get information from them.
The main cause of failure from surface breaking features such as you describe are the effect of the hydraulic pressure that the lubricant applies on the raceway as the feature is overrolled. This holds valid also for raceway surface breaking cracks.
For slightly sub-surface defects, a different failure mechanism comes in to play. This is the effect of compressive stresses on the Hertzian zone, and depending on the rolling element diameter can be between several hundredths of a millimetre to a small number of millimetres deep. This means that inclusions in this region are not recommended, and may shorten the bearing life.
I suggest that you request some information from a bearing manufacturer, and offer to hold the information obtained as confidential.