Description
Plain Washer M4 A4, ISO 7089 — BOLTON SKU 60693.
About the Plain Washer M4 A4 ISO 7089
The catalogue reference iso7089 m4-a4plain washer m4 iso identifies a plain washer to ISO 7089 in the M4 size, made from A4 stainless steel. ISO 7089 covers plain washers of the normal series in product grade A, and at M4 it fixes an inside diameter of 4.3 mm, an outside diameter of 9 mm and a nominal thickness of 0.8 mm. The washer spreads the clamping load of the bolt head or nut over a wider bearing area, protects the joint face from being scored by the turning fastener, and gives a consistent surface for the fastener to seat against so that applied torque translates predictably into preload. A4 is the molybdenum-bearing austenitic stainless grade of ISO 3506, chosen over A2 where chloride exposure — coastal air, salt spray or washdown — would pit a lesser grade. Pairing an A4 washer with A4 bolts and nuts also avoids setting up a dissimilar-metal couple within the joint itself.
Key specifications
| Attribute | Value |
|---|---|
| Standard | ISO 7089 — plain washers, normal series, product grade A |
| Size | M4 |
| Inside diameter (d1) | 4.3 mm |
| Outside diameter (d2) | 9 mm |
| Thickness (h) | 0.8 mm |
| Material | A4 stainless steel (ISO 3506 grade designation) |
| BOLTON SKU | 60693 |
Typical applications
M4 A4 washers are used under M4 nuts and screw heads on light brackets, enclosure and panel fixings, cable cleats, instrument mounts and equipment installed outdoors or in marine and coastal environments. The 9 mm outside diameter spreads load onto thin sheet and softer substrates where an M4 head bearing directly would emboss or dish the surface. Specify the mating screw and nut in the same A4 grade so that the corrosion resistance of the complete joint is matched rather than limited by its weakest component.
Supplied by BOLTON Technical Equipment Supplies against request for quotation. Add this item to your RFQ basket to request pricing, lead time and documentation requirements (e.g. CoC, datasheets or test reports where applicable).
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