Design of an automated on-car brake lathe

Abstract

An on-car brake lathe resurfaces disk-brake rotors by rotating them "in place" and making a light cut along the surface of the disk. The primary goal of this thesis is to develop an automated cutting head for an on-car brake lathe. The new cutting head must produce a surface finish that matches or exceeds that of the current (manual) cutting head. Pro-Cut International, a leading manufacturer of on-car brake lathes, developed functional requirements and cost constraints for the automated cutting head. Technical challenges include design and fabrication of low-cost precision linear bearings and actuators with dynamic stiffness sufficient to suppress chatter. During this thesis, two prototype cutting heads were designed, manufactured, and tested. The first prototype employed modular linear bearings, and produced unacceptable surface finish due to chatter. Cutting-tip vibration measurements combined with modal testing showed that chatter was caused by low structural stiffness of the modular bearing rails. A second prototype employing a unitary ground bearing system produced an acceptable surface finish of 70 [mu] -inch at 0.015" depth of cut per side. The key components of this design can be extruded and sliced to form the assembly, thereby meeting cost constraints.