Phosphate & Borax Coating
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The purpose of Zink phospate and subsequent lime or borax coating is to provide a carrier surface for the lubricant through the initial Rod Breakdown (drawing from Rod size to intermediate process size) A modern continous coating line consists of the phosphate section which includes a pre-treatment tank, zinc phosphoric acid tank, multiple stage rinsing followed by a borax or lime coating. The phosphate tank usually made of stainless steel incorporates a low density flat heat exchange surface and a sloped bottom to simplify sludge removal. The borax or lime tank can be either electrically or steam heated. All tanks usually have insulated materials and covers to minimize heat loss. Traditional batch dip tanks part of the pickling line are still widely used.
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