Materials testing for bearings rings and rolling elements
There are essentially two choices for the material used in ball bearings - chrome steel or stainless steel. Since the material plays a major part in the performance of a bearing in any given application, it is very important to use the correct material. Note that the specified material applies to the load-bearing components only - the rings and the balls. The retainer and the shields, if used, are usually made from a different material and are subject to separate specifications. Chrome steel is the standard material used for ball bearing applications where load capacity is the main consideration. The machinability of this steel is excellent, giving smooth, low-noise raceway finishes together with superior life. A chrome steel material is recommended in applications where corrosion is not a factor. Stainless steel is the standard material for miniature and instrument ball bearings where corrosion resistance is more important than load capacity. These materials have evolved in response to different manufacturing and application needs. It is important to note that the actual material used is generally determined by the manufacturer and cannot be specified by the user. The bearing’s metal structure is easily determined using the analytical instrument SPECTROMAXx made in Germany. This instrument is able to monitor the carbon signal during the pre-spark phase and to recognize the existence and proportion of free graphite in the sample.