Zinc Flake Coatings
The Anochrome Group has a number of dip-spin coating lines, as well as automated spray coating lines and a manual facility for large or awkward items.
What are the key performance advantages of zinc flake coatings?
- Excellent resistance to atmospheric corrosion.
- Limited “white” rust (zinc corrosion products) or other corrosion products in service.
- Complex shapes and sizes, recesses and holes are coated with suitable equipment.
- Neutral salt spray corrosion resistance exceeds that of many other common surface finishes e.g. electro and mechanically plated zinc.
- Good resistance to “mild” chemicals and solvents including petrol and brake fluids but not resistant to strong acids.
- No hydrogen embrittlement. It is a non-electrolytic process – most surface preparation is carried out by mechanical blasting.
- Has some degree of electrical conductivity.
- Galvanic protection by the zinc-rich coating ensures satisfactory performance at bimetallic contacts with steel, aluminium, zinc and cadmium in most situations.
What types of part are usually zinc flake coated?
- Threaded fasteners, particularly strength grades 10.9 and 12.9.
- Bolt, nuts, pressings, springs, clips, sub frames for automotive, wind energy, domestic appliances and building components.
These coatings are often used with a top coat that can improve corrosion resistance, give barrier protection, or act as a torque control or modifier, such as the Magni® System, Delta MKS® from Dörken®, and Geomet® from NOF® Metal Coatings (formerly Dacral®).
Dip Spin – planetary motion / tilts
The dip spin process involves placing the items to be coated into a perforated basket, the basket is then submerged into a tank containing the coating material, the basket is then removed for the material and then spun at a relatively high rpm to expel excess material. The planetary motion or tilts mechanism is designed to re orientate the parts during the spinning cycle so as to release coating material that would otherwaise be trappped in recesses etc. This then reduces the levels of recess infill that would otherwise be present in a standard dip spin coating process.
Parts can be processed using automatic CNC programed robotic equipment, this may require initial investment in bespoke tooling.
Parts processed with manual input, generally means reduced capital outlay on bespoke tooling.