A plain bearing was used in an automatic decanter centrifuge, which involves a medical appliance that separates the components of the patient's blood and concentrates those that can be used during an operation. Swinging bowls, which are fastened on a rotor, automatically separate the different blood proteins. The bowls swing with centrifugal force and are aligned by these forces. Previous designs used metal bearings and stainless steel shafts. The bearings used to wear out and get jammed, which made a squeaking noise. This caused undesirable ambient conditions, particularly as they are used in a medical environment, where minimal noise is important. This noise also pointed to future mechanical problems.
An immediate solution was to lubricate the bearings with oil. The company had to send pin-size little tubes to all its customers, with instructions how the lubricant needed to be applied to rectify the problem.
This meant significant costs, solved one problem but created a new one at the same time. The procedure was dirty and the oil attracted dust and dirt in the axle area.
The permanent, ideal solution was the replacement of the metal bearings with iglidur® G300 plastic bearings. The costs were significantly reduced immediately. With iglidur® bearings, only standard machining tolerances are required, whereas metal demanded precise machining and finishing. In addition to the revolved surface, iglidur® also offers a lateral bearing surface.
The company was able to reduce its costs by 93%! The assembly times were reduced by 10 minutes. The maintenance, which was only grudgingly carried out by the customer, was completely omitted.
"The biggest item of expenditure were the hidden costs, the fact that no more customers used to call and tell us that their machine was making strange noises, was priceless on the other hand.... iglidur® bearings are a designer's dream components: they solved a problem AND they cost less!" said the mechanical engineer at the company.