An automotive parts supplier needed to permanently retain a sound-deadening baffle plate inside an engine cover. Screws were expensive, time-consuming to install, and tended to fall out over time.
What they needed was a permanent, cost-effective solution. Orbitform's application engineers suggested Orbitally forming tenons molded into the die-cast A380 aluminum cover.
One issue was the tolerance in lining up the cast tenons on the cover with the holes on the baffle plate. The holes had to be oversized, and A380 aluminum can only form so far without cracking. Orbitform engineers suggested that a cone shape, similar to a Belleville washer, be stamped into the holes on the baffle plate to snug up to the formed tenon if tolerances were off.
Then extensive testing in Orbitform's Solutions Lab determined the optimal tenon geometry. To form the tenon's head, Orbitform's engineers developed a captured conical peen to contain the A380 aluminum during forming. In addition, die-cast aluminum is abrasive, containing around 8% Silicon, causing excessive tool wear and galling. Coating the M2 steel peen with Titanium Nitride extended the tooling life.
Because the tenons were close to walls and on different planes, it was impossible to use a height-sensing pressure pad to monitor and control the form. Instead, the orbital riveter was programmed to form to a force, creating a permanently formed head within the tolerance of the cast aluminum tenons and baffle plate.
Download our whitepaper on Permanent vs. Non-Permanent Assembly for more information.