Tanner emphasizes that even the most knowledgeable customers are wise to heed the advice of insert experts on their designs. He describes one such instance where an injection molder working for a major automaker had spec’d a threaded brass insert with diamond knurling for a new product they were set to produce.
“Fortunately, the OEM conducted an initial test with the insert, where it became evident that the design they selected was somewhat problematic for their production process, ”Tanner explains. “Before they could place the million-plus part order, they needed a solution, fast.”
Fearing the issue could force production backups, cost run-ups, and missed deliveries for the OEM, Tanner took the issue to one of his primary insert suppliers, Tri-Star Industries. Tri-Star specializes in threaded inserts and compression limiters for plastics.
“What we found was that the knurled surface of the inserts was chipping slightly, both in transit and as the inserts were bulk-loaded into the injection molding system (a standard operation),” says Tanner. “As a result, the accumulation of these small chips was gumming up the automated injection molding process, causing expensive unplanned downtime.”
The technical support team evaluated the specs from the injection molder and considered the end products various requirements before developing drawings for Tanner to review with the molder. Those included the idea to modify the knurling, or the grooved pattern (often diamond-shaped) on the outside of the insert, which helps keep its place.