A number of years ago a large company came to us because their wheel was the number one warranty claim in the entire company’s product line. It was costing the company millions of dollars each year to replace the wheels in the field.
The wheel had several problems.The oil impregnated sintered bronze bushing which dripped lubricant on the floor if too much had been applied during assembly and made terrible squeaking noise if too little lube was used.. The other problem was with the rubber on the outer edge which took a compression set from sitting stationary too long. When the owner would use the product for the first time, a rumbling noise would come from the unit because the wheel was no longer round.
We were told that the part had to survive a 1500 hour life test in a 100% humidity 175 F environment.. Our solution was to replace the bronze bushing with a high performance specialty compound specifically designed for this application. We used the same grade and durometer of elastomer as the original wheel. The design of the outer covering of the wheel was redesigned too. Instead of a tall side wall tire design like the original wheel, we went with a low profile racing tire design. The last change made was in the body of the wheel. We replaced the thick walled talc filled polypropylene rim, flange and hub with a thinwalled glass filled nylon. Thin reinforcing ribs on each side of the flange were positioned to improve stiffness and stability.
The result? Our polymer bushing showed no wear after completing a life test that ran 2X longer than the standard.This test was conducted without any lubricant. The new elastomer design did not take a compress set when sitting stationary for long periods of time. We were told by the project engineer that current production design, had never passed the life test or even gotten close. This metal to plastic conversion of the bushing and the redesigned wheel eliminated all the warranty issues the wheel had, required no additional lubricant of any kind and yielded a weight reduction of 60%. These design changes would save the company millions of dollars in warranty claims.
International Plastics specializes in the molding of all grades of engineering polymers. Including PEEK, PPS, Amodel, Radel, POM and LCP.
Contact International Plastics today to discuss your next project or to solve a performance problem in your existing product.