Recently one of the sawmill experts with Redwood Plastics started a test for a superior dry kiln fan bearing. Typically the standard bearings for the application are ~$1300.00 and we were asked to come up with something better and less expensive. Originally Redwood Plastics’ standard material for this application (Redco 750 polyurethane) was considered but was expected to deform under the high heat and friction the bearings will be subjected to. A bearing engineer was consulted and Rulon LR was found to be the optimum material; however, to machine a bearing of the size required for this application out of Rulon would be prohibitively expensive.
Instead, a decision was made to machine a bearing housing out of 30% glass filled nylon which, due to the glass content, has much higher dimensional stability at elevated temperatures. The Rulon LR was still used, except as an insert on the ID of the bearing. Because the customer was using an “auto lube” system grease grooves were machined on the Rulon – but for the record, Rulon can run completely “dry” in most applications! A test with ten of these new bushings is under way and after all this work – they did end up less expensive than the traditional bushings.
A picture of the application:
