Solving lint contamination at a powder coater

A Powder Coating Trade Coater had a quality problem with contamination (mostly fibres) on coated pressed panels and galvanised panels.

The investigation

The Company uses a small box type washing machine for the smaller parts. This provides a light iron phosphate pre-treatment. Most of these panels were coated “right first time”. The problem was the large parts that had to be manually prepared. Initially they were hand cleaned with a solvent and rag then primed with a chromate containing two pack etch primer. They suffered from lint contamination (fibres) visible in the coating when the cloth snagged on panel edges. They attempted to solve this by using a competitor’s solvent impregnated cloth but found the lint issue, while reduced, did not go away. They still suffered very high re-work rates. On investigating the existing rags and wipes, it was apparent (see the pictures below) that the existing wipe was based on a cotton fabric, as were the previous rags. By contrast our non-woven synthetic cloth used in W-710 even when snagged on the panel edges did not leave lint fibres behind.

competitors fabric compared with our fibre free tack cloths

The competitors product (left) exhibiting many loose lint fibres. The CT Cloth (right) is almost free of lint fibres.

The result

By switching to W-710 the customer significantly reduced his reject rate and virtually eliminated fibre defects. They are now further considering using our W-720 pre-treatment wipes that can produce a similar light iron phosphate coating as in the washing machine. This may allow the customer to avoid the use of the (toxic) chromate containing two pack etch.

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