Aerospace Shafts Microfinished for Improved Surface Quality

Microfinishing is the process that removes the microscopic amorphous surface material left from the grinding of a dimensionally finished part, such as a crankshaft, camshaft, or pump shaft, to permit a highly precise fit to a mating part. It is used to generate the final functional surface texture required for friction reduction, higher performance, and greater reliability of the precision shafts. Microfinishing tolerances are unattainable with grinding. The single-station Microteq CNC microfinishing system from IMPCO (Lansing, MI) can process a family of 68 aerospace control surface actuation shafts to better than 0.1 Ra while creating a functional surface for the component. Other tribological surface parameters are used for this post grinding application on HVOC (tungsten carbide) coated steel shafts. Besides meeting surface finish requirements, the Microteq reduced the cycle time to process the shafts from minutes to seconds, with a consistency from feature to feature and part to part. This machine uses an exclusively designed and built microfinishing attachment that is loaded with abrasive film.

Previously, each of the shafts in the family of parts had to be set up manually, then processed by hand resulting in inconsistent part surface quality, across the journal, from feature to feature and part to part. The flexible Microteq machine is designed to microfinish different diameters up to 75 mm on any precision load-bearing shaft to 1,000 mm long. Loading and unloading may be manual, automatic, or robotic. In operation, the shaft is loaded horizontally between centers and rotated with a head stock as the microfinishing attachment automatically approaches the part. The microfinishing head, loaded with abrasive film, travels on a horizontal slide to contact the shaft and the process begins. After predetermined cycle time, the head returns to its starting point or can move laterally to microfinish an adjacent diameter. The head stock, with independent geared drive, rotates the part at a predetermined speed between 100 rpm and 1,000 rpm.

Industrial Metal Products Corporation (IMPCO), 3417 West St. Joseph Street, Lansing, MI 48917, 517-484-9411, Fax: 517-484-0502, www.impco.com.