Flat Washer

A flat washer is a thin plate with a central hole placed beneath a fastener head or nut. It spreads bearing load, protects the joint surface and can bridge an oversized or slotted hole. Buyers should specify washer series, inside and outside diameter, thickness, hardness, material and coating. Standards listed here govern particular forms and do not make sizes, materials or finishes interchangeable. The RFQ should state the exact standard or drawing, required configuration, quantity and inspection evidence. This directory entry covers flat washers as components in fabricated metal product manufacturing. The operating principle is that the washer increases bearing area so the same clamp load produces lower local contact pressure. Selection requires confirming the applicable standard, nominal size (hole series), material, strength/performance, surface finish, and other RFQ fields against the selected standard and supplier evidence. Materials on file include steel, stainless steel, and non-ferrous material by specification. The listed standard ISO 7089:2000 is a procurement reference; it does not certify compliance. Always verify model-specific values and standards with the legal manufacturer or supplier before purchase.

The washer increases bearing area so the same clamp load produces lower local contact pressure. This reduces the risk of surface deformation or damage to the joint components. The washer also helps distribute the load more evenly, which can improve the stability of the connection. In practice, the washer acts as a load-spreading element, preventing the fastener head or nut from embedding into the softer material of the joint. It also provides a smooth bearing surface, which can reduce friction and wear during tightening. The effectiveness of the washer depends on its dimensions, material, and hardness, which must be matched to the application requirements.