by Kathy Levy
Jack Champaigne, President of Electronics Inc., recounted an experience in a recent article for The Shot Peener magazine. He was at an OEM’s facility when a call came in from one of their customers. The bucket conveyor belt had failed for the second time on a machine manufactured by the OEM. After a bit of scrambling and research, the staff shared their findings with Mr. Champaigne.
The machine was operating very successfully. Then a new media supplier approached the purchasing agent, offering longer life media. Since the company was consuming a large amount of media each month, this sounded promising so the purchasing agent bought the alternate brand. He thought he was going to save the company a lot of money.
After adding new media into the machine, the maintenance person noticed he had to readjust the belt on the bucket elevator. Not just once, but frequently. He also reported the media hopper seemed to be a lot hotter than usual. Why did the new media make such a big difference? When regular hardness media (a.k.a. “longer lasting” media) was substituted for the original high-hardness media, the shot peening process was changed. The new media was softer and it didn’t make the same size dent on the component. In fact, the media, being too soft, changed its shape instead of changing the surface of the component. Changing the shape of media caused friction and friction caused heat. The media hopper became hotter and stressed bucket conveyor belt until it failed. And that’s not the worst of it—components were not being properly shot peened.
This story highlights why your purchasing agent should be on your shot peening team. Changing media or suppliers can be a good idea, but media is a critical factor in shot peening and many parameters are based on it. An informed purchasing agent knows to consult with a key member of the shot peening staff before changing media vendors or products. As this story illustrates, a change in media affects the quality of the shot peening process and can cost the company money due to downtime. More importantly, improper shot peening creates a liability for the company.