The NES Five-Ball tester captures many of the intricate mechanics of bearing fatigue making it very attractive for simulation of full-scale bearing testing of ball bearings without full-scale costs.
The upper drive ball simulates the inner ring, the cup supporting the lower four balls models the outer ring and the four planetary balls replicate the balls in a bearing. Five-Ball testing can be used to qualify ball manufacturers, verify material lot integrity, investigate lubricant effects on fatigue life, study ceramic ball material and process quality, and determine heat treatment life factors. This modern version of the original NASA testers is designed to run at speeds up to 10,000 rpm and stress levels up to 900 ksi (6.2 GPa) on ball diameters up to 1 ¼”. The NES tester controls lubricant flow, oil temperature, rotational speed, and applied load while monitoring support cup temperature and system vibration for automatic shutdown.