How to Select Right Coating for fasteners
Geomet 321-500 Coated Fasteners
GEOMET® 321 is a non-electrolytic (water based) coating formed by thin-film of Zinc & Aluminum flakes to prevent corrosion on Fasteners. It doesn’t have chromium (No Cr6 neither Cr3) making it ROHS compliant and fulfills the requirements of EU Directives 2000/53/CE and 2002/95/CE alternative to DACROMET Coating.
No hydrogen embrittlement in Geomet Coating thus Prevent cracking of metals.
GEOMET® 500 is a self-lubricated basecoat, which allows obtaining a stable and controlled friction coefficient in the range of 0.12-0.18.
GEOMET® 321 and 500 coatings are versatile and effective solutions for corrosion protection on Automobile Fasteners, Wind Turbine Bolts and other High Corroion metallic bolts Application, offering a combination of corrosion resistance, lubricity, and other desirable properties.
Dacromet 320-500
Dacromet® is a zinc and aluminum flake coating, typically applied using an inorganic chromic acid solution as a Binder. Overlapping Zinc & Aluminum flakes provides excellent barrier, Thus use of Dacromet® coated Nut Bolts is considered to be ideal for applications that have high corrosion resistance requirements. Dacromet® coated screws is that the coating exhibits good heat resistance while offering a low friction coefficient.
The danger of hydrogen embrittlement does not exist. The Dacromet® coating process takes place in an aqueous media, where the application of the layer takes place with the dispersion of chromate zinc flakes in an aqueous dip-spin process. The coated layer is then dried, followed by subsequent burning at a temperature of 300 °C.
The Dacromet® Coated Fasteners also exhibit superior resistance to mechanical damage.
Dacromet® 500 also has a Self lubricant.
Hot Dip Galvanizing for Fasteners
Hot Dip galvanization to fasteners is most Widely used Coating. This is the process by which zinc coatings are obtained on iron or steel products by immersing them in a zinc dip. This HDG Coating process to Bolts & Nuts provide strong protection against corrosion is ideal for marine Fasteners, railguard Bolts, Construction Bolts Assembly and other highly corrosive industrial fasteners to protect them from corrosion. It adds a certain thickness to the coated parts (normally between 45-65u) which at times requires the retouching of certain areas, mainly threaded areas.
Electroplated-Zinc Coating
This is a coating for a metallic part with a zinc dip for rust and corrosion protection, even improving the visual appearance. The zinc coating can be obtained by electrolytic or mechanical processes. It is normally served without CRVI, that is, free from HEXAVALENT CHROMIUM and with a shiny silver appearance, although other finishes are possible depending on requirements.
Black Annealing
This is the immersion of iron objects in a boiling alkaline-oxidising solution. With black annealing, dark black surface layers are generated on iron objects.
