APPLICATION
We were asked by a major national food manufacturer to solve a problem they were having with seals in a depositing machine which was depositing jam into doughnuts.
THE PROBLEM
The seals within the depositing head were simple O Rings, and the problem was when the slide out part of the head was withdrawn, the O Ring seals sometimes would become loose, and try to drag out from their housing, causing them to get trapped & damaged, and thus small pieces of rubber falling into the product system causing contamination.
THE SOLUTION
The approach to this was via 2 considerations.
Firstly, it was decided to make improvements to the seal design. The simple O Ring was replaced with a bespoke, custom profile seal which would allow much tighter control over the tolerances, provide a tighter fit in the housing, with a profile which would not be prone to being dragged out of the housing.
The second consideration was the material used for the seal. The material chosen was blue metal detectable HNBR. This material gave the benefits of a durable, hard wearing nitrile, in the preferred colour of blue for visibility, and the added benefit of detectability, in the unlikely event that the seal did get damaged and parts fell into the product stream, they could be detected and rejected by the in-line metal detection process.
OUTCOME
An initial small batch was ordered and manufactured for testing purposes. Following lengthy trials, it was established that the new replacement seal proved successful, finding that it was remaining firmly in it’s housing, and no damage occurring.
Following the successful trial, the new sealing solution was approved, and was implemented as the standard replacement seal.
