Measuring Machining Imperfections and Runout in Automobile Wheel Spindles
Introduction
Problem
No grinder produces a perfect surface. Grinder wheel runout, improperly dressed wheels and fixture vibrations can cause chatter on the spindle surface finish. Chatter is a series of microscopic, repetitive imperfections, or waves, in the surface of the material being machined. A large, Tier 1 Supplier to the automotive industry approached MTII looking for a method to measure and classify these imperfections as a 100% quality control check. They required a production environment sensor that had small spatial resolution, high frequency response and large standoff distance for easy loading and unloading of parts. Additionally, the measurement accuracy had to be less than 4 micro-inches (0.1 microns) with a resolution of 1 micro-inch (0.025 microns), or better, in order to properly quantify the defects. System noise had to be kept to a minimum in order to prevent unnecessary parts rejection and scrap.
Solution
Results
The system was able to quickly measure, sort, and thus pass or reject each spindle measured. This early process check not only improved throughput, but also prevented poor quality parts from further machining steps, saving thousands of dollars in the first month of operation. By working closely with this supplier, additional applications such as wheel flange runout and wheel bolt position have been solved with similar techniques.
MTI Instruments Inc offers several styles and types of non-contact capacitance sensors. The passive probes offer excellent thermal stability and are capable of temperatures in excess of 600°C. MTII also manufactures high precision laser and fiber-optic systems with resolutions to 0.04 micro-inch (1 nm) and frequency responses to 500 kHz. Contact MTI’s experienced Application Engineers for solutions to your difficult measurement needs.
