Process for coating threaded metallic pieces

摘要

The process for coating a threaded metallic piece comprises in sequence the steps of: using this piece as cathode of an electrolytic cell, wherein a bath containing at least Zn ions is present, whereby the electro-deposition of a first layer containing Zn is brought about on the surface of the piece, and applying on the piece coated by the first layer a second layer of a polyester-based paint.