Skip to content
info@engineeringhardware.com
WhatsApp
Request a Quote
Washers · ISO 7094 · Application guide

What Are Flat Washers, Extra Large Series Used For?

Typical applications, the industries that specify flat washers, extra large series, and how to choose the right size, material and finish for the joint.

Flat Washers, Extra Large Series are used for a plain washer with an extra large outside diameter for soft materials and oversized holes. They are manufactured to ISO 7094, and selection is driven by the nominal bolt size, the fit and tolerance the assembly requires, and the service environment.

Primary duty
A plain washer with an extra large outside diameter for soft materials and oversized holes
Governing standard
ISO 7094
Nominal bolt size range
M5 to M36
Category
Washers

Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation.

What Are Flat Washers, Extra Large Series Used For? application image

Flat Washers, Extra Large Series are used primarily for a plain washer with an extra large outside diameter for soft materials and oversized holes. This page lists the industries and assemblies where they are specified, the selection criteria that matter for each application, installation practice, and the cases where a different fastener type is the correct choice. Parts are supplied to ISO 7094. Stocked across roughly M5 to M36, they cover general to heavy-duty work.

Typical Applications for Flat Washers, Extra Large Series

The most common settings where these are specified:

  • Timber construction: bolts through timber.
  • Plastic and composites: load spread on soft material.
  • Sheet-metal work: oversize or slotted holes.
  • Automotive repair: body panel repairs.

How to Specify Flat Washers, Extra Large Series for Your Application

  • Size: Match the nominal size to the mating thread or hole. This product spans M5–M36; check the full table below for the exact dimensions of each size.
  • Type & OD: Select flat for load spreading, spring/serrated for anti-loosening, or fender/large-OD for soft or oversized holes.
  • Environment: For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
  • Standard: This product is supplied to ISO 7094. Quoting the standard on your order guarantees interchangeable dimensions between suppliers.

Installation & Assembly Practice

  • Place the washer under the rotating element (usually the nut) so tightening does not score the surface.
  • Chamfered-hole side of a hardened washer faces the bolt head fillet.
  • On serrated-flange hardware, do not add a plain washer — it defeats the serrations.

Common Selection Mistakes with Flat Washers, Extra Large Series

  • Relying on a spring washer for locking on class 8.8+ joints — at high preload it flattens and adds nothing.
  • Choosing an OD too small for soft material, so the head pulls through or embeds.

Where Flat Washers, Extra Large Series Are Not the Right Choice

A washer does not replace a locking feature on its own in severe vibration, and a spring washer adds little clamp on high-strength joints.

Custom manufacturing · Made to drawing

Need a flat washers, extra large series outside the standard range?

Bore and outside diameter are set by the joint rather than by the bolt, which is why an off-table size is so often the right answer. Made by stamping or punching.

Minimum order from 2,000 pieces; samples within 7 days of drawing approval.

Custom washer manufacturingSend a drawing

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Dimensioned line drawing of M5 Flat Washers, Extra Large Series to ISO 7094. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.
Inner diameter d1 (mm)
5.5
Outer diameter d2 (mm)
18.0
Thickness h (mm)
2.0
h_max (mm)
2.3
Sends the selected values to the quote form below.

Request a Quote

The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.

Request a Quotation

Specification
Business Information

Dimensions & Specifications (ISO 7094)

SizeInner diameter d1 (mm)Outer diameter d2 (mm)Thickness h (mm)h_max (mm)Reference standard
M55.518.02.02.3ISO 7094
M66.622.02.02.3ISO 7094
M89.028.03.03.6ISO 7094
M1011.034.03.03.6ISO 7094
M1213.544.04.04.6ISO 7094
(M14)15.550.04.04.6ISO 7094
M1617.556.05.06.0ISO 7094
(M18)20.060.05.06.0ISO 7094
M2022.072.06.07.0ISO 7094
(M22)24.080.06.07.0ISO 7094
M2426.085.06.07.0ISO 7094
(M27)30.098.06.07.0ISO 7094
M3033.0105.06.07.0ISO 7094
(M33)36.0115.08.09.2ISO 7094
M3639.0125.08.09.2ISO 7094
Inside the plant

Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

  1. Wire rod feeding into a cold heading machine
    01

    Cold heading

    Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.

    Head dimensions and under-head radius checked at set-up and per shift.

  2. Thread rolling machine producing bolt threads
    02

    Thread rolling

    Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.

    Go / no-go ring gauges to ISO 965 tolerance class 6g.

  3. Baskets of bolts staged for heat treatment
    03

    Heat treatment

    Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.

    Core hardness and tensile tested per lot to ISO 898-1.

  4. Zinc plated bolts in a treatment basket
    04

    Surface treatment

    Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.

    Coating thickness and neutral salt spray hours to ISO 9227.

Frequently Asked Questions

What material should Flat Washers, Extra Large Series be for outdoor use?

For damp, coastal or chemical environments specify A4 (316) stainless or a suitably coated steel. For indoor or dry use, A2 (304) stainless or zinc-plated steel is normally adequate.

Are Flat Washers, Extra Large Series made to a recognized standard?

Yes — they are manufactured to ISO 7094, so dimensions are interchangeable between suppliers when you quote the standard on your order.

What are Flat Washers, Extra Large Series used for?

A plain washer with an extra large outside diameter for soft materials and oversized holes. They are supplied to ISO 7094.

Which industries use Flat Washers, Extra Large Series?

They are commonly specified in sheet-metal work, automotive repair and timber construction, among other sectors.

Can I get a quote for Flat Washers, Extra Large Series in the size and material I need?

Yes. Use the technical drawing and quote form on this page to set the size and options, then send the exact configuration to our team for pricing and lead time.