Aerospace shafts microfinished for improved surface quality

A single station CNC microfinishing system processes 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 IMPCO Microteq Microfinsher reduced the cycle time to process the shafts from minutes to seconds in process time, with a consistency from feature to feature and part to part. The IMPCO MICROTEQ CNC machine uses the company’s exclusive designed and built microfinishing attachment 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 IMPCO machine is designed to microfinish different diameters up to 75mm on any precision load-bearing shaft to 1,000mm in length. Such shafts are used in pumps, compressors, aerospace control surfaces, and transmissions. Loading and unloading may be manual, automatic, or robotic.

In operation, the shaft is loaded horizontally between centres 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 microfinishing head and is returned 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 and 1,000rpm.

“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,” said Mark Hendel, IMPCO global sales director. “IMPCO microfinishing 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.”

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