Precision Control of Miniature Bearings: Measuring Tools and Inspection Techniques 

1. “Precision battlefield” - quality control of miniature bearings

When working with miniature bearings with an internal diameter of less than 10 mm and a wall thickness comparable to a cicada's wing, the accuracy limitations of traditional universal measuring instruments become apparent. In the precision battleground of bearing manufacturing, the inspection phase acts as the quality guard, requiring the assistance of a range of professional weapons, from standard parts to specialty instruments, each with the goal of achieving micron-level precision. In this article, we will break down the basic toolkit for microbearing inspection and combine practical skills to provide engineering personnel with practical application guidance.

2. Basic testing instruments: in-depth analysis of accuracy and methods

"Ruler" as a standard: the logic of comparative measurements using standard parts

When inspecting miniature bearings, the “comparative measurement method” plays a key role in ensuring accuracy. A standard part is used as a “reference ruler”, the accuracy of which is usually one class higher than the accuracy of the bearing being tested (for example, class G bearings are calibrated using standard class E parts). Thus, when measuring the internal diameter using the D902 device, it is necessary to first calibrate the zero position of the tool using a standard ring, and then evaluate the product’s compliance with the requirements by comparing the deviation of the measured part with the standard indicators. The essence of this method is to “measure the unknown by means of the known,” which effectively eliminates systematic errors inherent in conventional measuring instruments.

Rational use of calibers: limiting calibers and the “optical gap” method

To control complex geometric parameters of the contour - such as the radius of curvature of the groove and its position - an effective method of qualitative verification is the use of limit gauges in combination with the “optical gap” method.

Control of groove curvature: a template gauge is applied to the bearing raceway, after which the uniformity of the resulting optical gap is assessed. If the optical gap is a continuous thin line (≤ 0.5 µm wide), the radius of curvature is considered to meet the requirements; The presence of intermittent light spots indicates local wear or processing defects on the raceway surface.