Bradford Machine Company

Bradford Now Offers Bearing Ratio Superfinishing

Achieving Bearing Ratio, Rmr, and other Surface Parameters

Bradford Machine now offers superfinishing of parts to achieve specifications for bear ratio, Rmr, and other surface parameters, typically Ra, Rp and Rz. We can manufacture the part complete or we can achieve your requirements on parts you provide. As a service turnaround time is a week or less once the machining process has been designed.

What is superfinishing?

Increasingly manufacturers are realizing the benefit of specifying bearing area or bearing ratio parameters for the lubricity and wear characteristics of surfaces. Two industries in which these parameters are becoming more common is automotive and aerospace where surface wear properties are important.

Bearing ratio is the ratio (expressed as a percentage) of the length of the bearing surface at any specified depth in the evaluation area. It simulates the effect of wear on a bearing surface. In connections with other surface parameters such as Ra, Rp and Rz it also influences lubricity and therefore longevity of the parts.

How is superfinishing done?

Superfinishing combines workpiece rotation, tool oscillation and pressure. In doing so, each individual grain of the abrasive tape travels along a sinusoidal line. Contact between the workpiece and the oscillating abrasive thus creates a characteristic cross-hatch pattern of grooves and plateaus on the workpiece. The grooves act as channels to aid in uniform distribution of lubricant, while the plateaus guarantee a high percentage of contact area.

Superfinishing requires special equipment to achieve and measure the finished surfaces. Bradford Machine is able to do both.