Burnishing is a conversion treatment, a transformation process (DIN 50983), which transforms the surface layer of steel into magnetite by immersion in alkaline salts at 130–150 °C.
It is used when a uniform, anti-reflective black finish, light corrosion protection and no dimensional variation are required, with increased effectiveness through final oiling. It is used to reduce friction and wear, protect against moisture and improve the aesthetics of components in non-extremely aggressive service.
Typical sectors: mechanical, automotive, armoury, tools and precision mechanics, for gears, shafts, equipment and bolts.
The systems include tank lines with degreasing/activation, burnishing bath, rinsing, neutralisation, oiling or sealing and controlled drying.
Handling is carried out on frames for large parts and rotary barrels for small parts; the bath is kept at boiling point for 5-30 minutes.
Cold burnishing is available for touch-ups and aesthetics, but offers less protection than the hot cycle.
Ceever designs and manufactures automated burnishing systems that can be programmed and integrated with production management platforms (MES).
