Buy Cup Washers Online in Australia
Cup Washer (Penny / Repair Washer) Selection — Quick Reference
Cup washers (penny washers / repair washers) = OVERSIZED BEARING SURFACE under bolt heads + screw heads — DISTRIBUTING clamping load over LARGER AREA + preventing pull-through in soft materials + oversized + damaged holes.
| Cup Washer Type | Best For |
|---|---|
| Standard Penny Washer | Wood + soft material + standard hole pull-through |
| Repair Washer | Oversized + damaged hole — large OD |
| Cup Washer (Domed) | Aesthetic + decorative — covers fastener head |
| Heavy-Duty Penny Washer | Higher load + thicker section |
| Zinc-Plated Standard | Workshop + general |
| 304 / 316 Stainless | Corrosion + outdoor + chemical |
| Hot-Dip Galvanised | Heavy outdoor + extended corrosion |
| Common Metric (M6-M16+) | Workshop standard |
| Common Imperial (1/4"-1/2"+) | US-origin equipment |
Critical: Cup/penny washers distribute clamp force = essential for SOFT material + LARGE holes. Don't substitute for proper lock washer when vibration security is the goal — penny washer = bearing surface only. Match OD to surface needing protection. Companion: flat washers, spring lock washers, lock washers, fasteners.
Cup Washers
Cup washers (penny washers or repair washers) provide an oversized bearing surface under bolt heads and screw heads — distributing clamping load over a larger area and preventing pull-through in soft materials and oversized or damaged holes. AIMS Industrial stocks cup washers in zinc-plated steel and stainless steel across a range of bolt and screw sizes for construction, maintenance and repair applications.
When Cup Washers Are Used
Cup washers are specified in timber and lightweight panel construction where standard flat washers would pull through under load — roofing and cladding fixings where oversize holes are common, repairs to fixing points where the original hole has wallowed out, saddle and strap connections in timber framing, and garden structures, fencing and playground equipment where weather exposure demands a large bearing surface at every fixing point to prevent localised crushing and water pooling around bolt heads.
Difference Between Cup, Flat and Structural Washers
A standard flat washer provides moderate bearing area increase — suited to general bolt and nut use in metal and dense materials. A cup washer provides a substantially larger bearing area — suited to softer materials and over-size holes. A structural (F436 or similar) washer is a precision-hardened flat washer for structural bolt connections with defined load-bearing properties. For most timber and sheet material repair and fixing applications, a cup washer is the appropriate choice.
Sizes and Materials
Cup washers are sized by the bolt/screw diameter they suit — M4, M5, M6, M8, M10 and M12 being the most common. Outer diameters typically range from 20mm to 50mm depending on the nominal bolt size and the amount of bearing area increase required. For help selecting the right washer type and size for your fixing application, contact our team. AIMS Industrial has been supporting Australian tradespeople since 1988.
People Also Ask — Cup Washers
Q: When is a cup washer the right choice over a standard flat washer?
A standard flat washer provides a moderate bearing area increase suited to general bolt and nut use in metal and dense materials. A cup washer provides a substantially larger bearing area, which is what makes it the right choice for softer materials and over-size or damaged holes where a flat washer would let the fastener pull through.
Q: What construction jobs typically call for cup washers?
Roofing and cladding fixings where oversize holes are common, repairs to fixing points where the original hole has wallowed out, saddle and strap connections in timber framing, and garden structures, fencing and playground equipment where weather exposure demands a large bearing surface at every fixing point to prevent localised crushing and water pooling around bolt heads.
Q: Does a cup washer help stop a fastener working loose under vibration?
No — a cup (penny) washer is a bearing surface only, distributing clamp force over a larger area. It shouldn't be substituted for a proper lock washer when vibration security is the actual goal.
Q: What sizes do cup washers come in?
Cup washers are sized to the bolt or screw diameter they suit — M4, M5, M6, M8, M10 and M12 are the most common — with outer diameters typically ranging from 20mm to 50mm depending on the nominal bolt size and the amount of bearing area increase required.
Q: What's the difference between a cup washer and a structural (F436-type) washer?
A structural washer is a precision-hardened flat washer for structural bolt connections with defined load-bearing properties. A cup washer is built for a different job entirely — softer materials and over-size holes in timber and sheet material repair and fixing, not structural bolted connections.