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Designing a true maintenace-free pivot

Tech Talks by igus helping solve design engineering problems with motion plastics

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tech talk Learn more at Disadvantages: a. Corrosion protection for the housing is removed b. The pin becomes a secondary wear surface due to the poor corrosion inhibitor c. Less expensive manufacturing costs, but a higher total cost of ownership due to the need to eventually replace the bushing, pin, and housing 1. There is no corrosion protection for the housing. • Corrosion will begin to form almost immediately on the inner portion, where there is no bushing material.This corrosion will flake off and begin to prematurely wear both the bushing and pin simultaneously. • Corrosion will begin to form between the outer diameter of the bushing and the inner diameter of the housing, which will cause the housing to shrink around the bushing. Doing this will reduce the clearance between the bushing and pin, and increase friction and the wear rate of the bushing. 2. The pin will deteriorate at higher rate due to the absence of an effective corrosion inhibitor. • Commonly used corrosion inhibitors, such as zinc, nickel, and chrome, are very thin layers applied to a pin and are quickly worn off during normal operation. • Once the inhibitor is removed, the base alloy gets exposed to the environment and the surface finish will become much rougher than any plain bushing can successfully run on. • This corrosion and degradation of the surface finish may be unnoticeable during continuous operation. However, once the machine is idle for any length of time, the corrosion will be able to expand rapidly, and in some instances, cause the pivot to seize altogether. By the removing grease used for lubrication, you have inadvertently introduced two critical issues that will cause premature failure in an application: Result of a housing without corrosion protection Result of using a thin, ineffective corrosion inhibitor on a shaft after only one season

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