How to choose the right material and finish for an ISO 7090 chamfered washer
Choose the material for the environment, the finish for corrosion and the hardness class for the bolt. Get those three right and the washer suits the joint.
Material: carbon steel or stainless
We make ISO 7090 washers in two materials:
- Carbon steel: for dry indoor use, or outdoors with a protective finish.
- Stainless steel: for wet, washdown, marine and mildly corrosive conditions. A stainless washer under a stainless bolt and nut also avoids galvanic corrosion.
For stainless, put the grade on your inquiry, for example A2 (304) or A4 (316), and ask for a material certificate if your project needs one.
Finish for carbon steel washers
Carbon steel washers need a finish to stop rust. We supply:
- Zinc plated: economical, for indoor and sheltered use.
- Hot-dip galvanized: a thick zinc layer for outdoor and structural work.
- Plain: no coating, for washers that are oiled, painted or kept dry.
Stainless washers come plain or passivated. If your specification sets a salt-spray life, put the hours and the test standard on the inquiry, for example 720 h to ISO 9227.
Hardness class: 200 HV or 300 HV
ISO 7090 has two hardness classes. Match the class to the bolt:
- 200 HV: for bolts up to property class 8.8, nuts up to class 8, and stainless fasteners.
- 300 HV: hardened and tempered steel, for bolts up to property class 10.9 and nuts up to class 10.
A washer that is too soft beds in under load, and the joint loses preload.
Dimensional checkpoints for quotation
An ISO 7090 washer is chamfered at the outside diameter. Size it by the bolt: we make M5 to M36. The inside diameter d1, outside diameter d2 and thickness h of every size are in the ISO 7090 dimension table.
Quotation checklist for ISO 7090 chamfered washers
Put these in your inquiry and we quote without back-and-forth:
- Standard: ISO 7090.
- Size: M__ (for example M12).
- Material: carbon steel or stainless steel, with the grade.
- Finish: zinc plated, hot-dip galvanized, plain or passivated.
- Hardness class: 200 HV or 300 HV, or the property class of the bolt.
- Quantity: pieces per size.
- Documents: material certificate or inspection report, if you need one.
Next step
Open the ISO 7090 dimension table, pick your sizes and send the checklist above with your inquiry.
