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Use 3 labelled dimensions
A flat washer is commonly described by its inner diameter (ID), outer diameter (OD) and thickness. Label all three values and state the units when sending an enquiry.
For example, ID 3 mm × OD 6 mm × thickness 1 mm is clearer than an unlabelled “3 × 6 × 1”. Confirm the supplier’s dimension order instead of assuming that every listing uses the same convention.
Treat metric designations as a starting point
A designation such as M3 may refer to the nominal fastener size. It should not be used as a substitute for a confirmed washer drawing, particularly when clearance, sealing surfaces or assembly space are important.
Provide the actual required dimensions and tolerances. If you are replacing an existing component, a sample and a dimensioned drawing help establish which features must match.
Include the material condition
Two washers with the same dimensions can have different material requirements. State the copper grade and whether a particular annealed condition or hardness is required for your application.
Describe the intended use so that material and inspection requirements can be reviewed. Temperature, pressure and sealing suitability must be evaluated for the actual assembly.
Check the approved specification before purchase
Review the drawing revision, dimensional tolerances, material condition, surface requirements and quantity together. Request agreed inspection documentation where your purchasing process requires it.
For assortment kits, confirm the size list and piece count for each compartment. The packing list should describe the contents of the configuration being supplied.