We can offer surface finishing as per customer requirement in hot dip galvanising, we take special care to ensure there is no hydrogen embrittlement in 10.9 grade with our special curing system which ensures that 10.9 grade bolts are not damaged by hydrogen embrittlement post galvanising process. We also do zinc electroplated in blue, yellow or black colour as per customer requirements.
Special coatings in specific industries require zinc flake coatings, these coatings are done as per ISO 10683, depending upon customers requirement for salt spray life we offer coating systems from NOF Japan and Doerken from Germany, these coatings are provided with the help and support of our partners who have the required licence and have successfully done validations with our existing customers. Salt spray life can vary from 500 to 1500 hours.
Black oxide or black coating is a general type of coating offered on bolts & nuts & stud bolts to give a pleasant appearance and to prevent any rusting during transportation or storage, the normal salt spray life for the fasteners applied with such coatings is often less than 100 hours
Xylan is a brand name of With fort USA and is a special coating applied on fasteners / stud bolts where extreme temperatures and harsh condition exist. The Highlights of this coating is that it gives
- Low friction CoF as low as 0.02.
- High corrosion and chemical resistance in most environments including marine and Oil & Gas
- "Wide temperature operating range: from -420° to +550°F (-250° to 285°C)"
- "Wide color range: color-code your product"
- Machinability: apply multiple coats of Xylan coating (most formulations) and mill to specification
- Wear resistance is very high, even under extreme pressures.
- Weather resistance: against sunlight, salt water and road chemicals
- Flexible curing schedule: ambient to 750°F (400°C).
- Pliability: Many Xylan coatings will bend freely and repeatedly without breaking.
- "Salt spray SST life: above 1000 hrs."
Chamfered are also through hardened washers made from alloying steel which are able to be hardened through hardening process, these are generally used with friction grip fasteners or preloading bolting assemblies. These are designed to stop the bolt head or nut embedding in the material being clamped or deforming when under load instead distributing the force onto the material over a wider area.
Manufacturing
Chamfered washers are made in multiple steps, these involve sheet cutting and then pressing and then punching and then machining followed by hardening and tempering and then finally coating as per customers requirements.