A specialised Apticote coating from Poeton Industries has 're-covered' a set of rusty filter moulds, recovering their performance and saving Sogefi Filtration over GBP25,000.

The South Wales based Coopers Division of Sogefi Filtration manufactures air, oil and fuel filters for cars and heavy goods vehicles. To produce an after-market air filter for a leading car range the company was using 150 sets of ferritic stainless steel moulds supplied by a sister company. Prior to production the moulds were coated with a PVC chemical, incorporating a release agent, which then had to be oven cured.

Despite the coating, the presence of carbon in the stainless steel caused the moulds to corrode, making it impossible to remove filters without ripping their seals.

A zinc coating applied by a local company also failed to prevent sticking; and even getting coatings to stick to the moulds was proving to be a problem.

It was at this point - with the company facing a GBP25,000 bill to replace the moulds - that the engineering department called in Poeton.

Says Gwyn Thomas of Sogefi: "By this time the moulds were in poor state and very badly rusted; and the profile meant they would be difficult to clean or polish".

He says: "In spite of their condition Poeton was able to apply a number of its Apticote coatings for us to test for compatibility".

Apticote 460G, one of a family of nickel polymer coatings developed for rubber and polymer moulding applications, produced the best result.

Its combination of permanent lubricity and high hardness enabled filters to be easily released and significantly extended the life of the moulds.

Gwyn reports that eighteen months later with an estimated 60,000 filters produced, there are no signs of wear or deterioration in the coating, even though a metal gauze inside the filters rubs against its surface during the process.