Flat Washers, Spring Washers & Fender Washers â Sourcing from China
Overview
Washers are a commodity fastener category, but dimensional tolerance and consistent thickness make a real difference in structural and high-torque applications. HDBolt sources from factories running automated stamping lines with regular tolerance checks.
Specifications
| Standards | DIN 125 A (flat), DIN 127 B (spring lock), DIN 9021 (fender / large OD), ISO 7089, ISO 7090, ASTM F436 |
|---|---|
| Size Range | M3 â M48 / #4 â 1-1/2" |
| Material | Carbon steel, Stainless 304/316, Brass, Copper |
| Finish | Plain, Zinc plated, HDG, Black oxide, Passivated stainless |
| Thickness Tolerance | Typically Âą0.1 mm, tighter on request |
| Packaging | Bulk cartons with desiccant, small bags, retail blister |
Frequently Asked Questions
What is the difference between DIN 125 and DIN 9021 washers?
Both are flat washers but differ in outside diameter. DIN 125 is the standard flat washer with an OD approximately 2x the bolt diameter. DIN 9021 (often called a fender washer) has a significantly larger OD â roughly 3x the bolt diameter â which distributes load across a wider area. DIN 9021 is used when clamping against soft materials like wood, plastic, or thin sheet metal.
Do spring lock washers (DIN 127) actually prevent loosening?
The effectiveness of split lock washers like DIN 127 is debated in engineering literature; several studies suggest they provide limited vibration resistance compared to alternatives like nylon insert lock nuts, wedge lock washers, or thread-locking adhesive. They remain common in specifications and general use, but for critical applications with heavy vibration, a more modern locking solution is usually recommended.
Can you supply ASTM F436 structural washers?
Yes. F436 hardened structural washers, intended for use with A325 and A490 bolts, are available. They can be supplied in plain or HDG finish with Mill Test Certificates traceable to the heat number.
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