Washers
— NAB and SAB

M4 – M64 Nickel Aluminium Bronze Aluminium Silicon Bronze Plain & Spring Made to Order
Standards
ISO 7089 · ISO 7090 · ISO 7093-1
Legacy
BS 4320 A / B / C · DIN 125
Forms
Plain · Large · Spring · Special
Quotes
Within 24 hours
No Minimum Order
Made to Drawing
Material Certification & Traceability
Quote Within 24 Hours
ISO 9001 BSI Certified
JOSCAR Registered
Overview

Plain washers to the dimensional requirements of ISO 7089 (normal series, no chamfer) and ISO 7090 (chamfered), legacy BS 4320 forms A, B and C where specified, large series to ISO 7093-1 or legacy DIN 9021, or any size to drawing, in nickel aluminium bronze (CuAl10Ni5Fe4 — CW307G / CA104) and aluminium silicon bronze (CuAl6Si2Fe — CW301G / CA107) to the applicable drawing or material specification. Spring washers, penny (repair) washers, tab washers and specials to drawing. M4 to M64 metric; 1/4" upward imperial. Supplied with material certification and, where specified, to NES 833 / DEF STAN 02-833 for NAB, NES 834 / DEF STAN 02-834 Pt 2 (superseded by 02-879 Pt 2 Annex D, Sept 2011) for SAB, and the DEF STAN 02-862 Part 2 route.

Washers are made from bar, or from sheet or strip where the material specification permits it. Under DEF STAN 02-862 Part 2 the permitted source forms are sheet, strip or bar, and no further heat treatment is applied after manufacture — the washer is supplied in the heat-treated condition of the certified feedstock. Where DEF STAN 02-833 or 02-834 Pt 2 (superseded by 02-879 Pt 2 Annex D, Sept 2011) material is called up, that in practice means certified rod or section, since those standards cover forgings, rods and sections rather than sheet or strip. Usually ordered with the matching bolts and nuts; supplied separately against drawing just as readily. No minimum order quantity.

Also known as: flat washer, plain washer, form A washer, form B washer, form C washer, ISO 7089 washer, DIN 125 washer, DIN 9021 washer, spring washer, split washer, DIN 127, penny washer, repair washer, mudguard washer, NAB washer, aluminium bronze washer, AlSiBr washer.
Dimensions

ISO 7089 plain washers — basic dimensions

Nominal values for the ISO 7089 normal series. ISO 7090 covers the chamfered normal-series washer from M5 to M64; its dimensions are close to ISO 7089 but not identical at every size, and are taken from ISO 7090 when that standard is called up. Legacy BS 4320 (withdrawn 2021, still called up on many naval drawings and by DEF STAN 02-862) is still the form reference most drawings use. Its form letters were partly defined by steel finish, which doesn't apply to bronze — we make to the dimensions of the form called up. Form A is the normal-diameter, normal-thickness washer (ISO 7089 corresponds most closely); form B is normal diameter, light thickness; form C is normal diameter with the slightly larger bore and outside diameter of the unfaced form. Large-series washers to ISO 7093-1 or legacy DIN 9021. Any other size to drawing.

ThreadInside dia d1 (mm)Outside dia d2 (mm)Thickness h (mm)
M44.390.8
M55.3101.0
M66.4121.6
M88.4161.6
M1010.5202.0
M1213242.5
M1415282.5
M1617303.0
M1819343.0
M2021373.0
M2223393.0
M2425444.0
M2728504.0
M3031564.0
M3334605.0
M3637665.0
M3942726.0
M4245788.0
M4548858.0
M4852928.0
M5256988.0
M566210510.0
M606611010.0
M647011510.0
Other forms: spring (split) washers to the DIN 127 (withdrawn) or BS 4464 pattern, used as a form reference only — these are spring-steel standards, spring washers in bronze have a lower spring rate than steel, and manufacture in NAB or SAB is subject to manufacturing review; tab, wave, serrated and shaped washers to drawing.

Non-standard bore, outside diameter or thickness, and imperial sizes, to drawing — see Made to Drawing.

Materials

Materials

DEF STAN 02-833 / NES 833 — Nickel Aluminium Bronze (CW307G / CA104)

CuAl10Ni5Fe4. The higher-strength alloy, with excellent seawater, erosion and cavitation resistance; commonly specified for structural and immersed fastenings. Naval material standard NES 833 / DEF STAN 02-833 Part 2. Relative magnetic permeability typically around 1.4–1.5. Full data, designations and cross-references on the NAB material page.

NES 834 / DEF STAN 02-834 → 02-879 Pt 2 Annex D — Aluminium Silicon Bronze (CW301G / CA107)

CuAl6Si2Fe. Good machinability, ductile, and formulated for controlled low magnetic permeability — relative magnetic permeability not exceeding 1.05 (DEF STAN 02-879 Part 2 Annex D, D.2.8; batch-tested to D.4.5) — used for mine countermeasures vessels and other naval low-signature applications. Tighter permeability limits are a drawing or contract requirement and are handled at enquiry stage. Naval material standard NES 834 / DEF STAN 02-834 Part 2, subsequently incorporated into DEF STAN 02-879 Part 2 Annex D. Full data on the SAB material page.

Certification

Source-material certification supplied as standard, with traceability to the bar heat maintained through manufacture. Where the drawing calls for DEF STAN 02-862 Part 2, washers are made from sheet, strip or bar with no further heat treatment after manufacture, per clause 8.2.4 (NAB) or 8.2.5 (SAB). Source-material certification and batch traceability are maintained through manufacture; any finished-product inspection or certification is supplied as required by the order. Marking, EN 10204 3.1 certification, dimensional inspection reports and CoC as required by the order; EN 10204 3.2 where agreed in advance and supported by the material source and inspection arrangements.

The drawing and specification govern. Alloy designations above are cross-references, not statements of equivalence.

FAQ

Washers — Common Questions

What's the difference between form A, B and C washers? +
BS 4320 forms: A is the normal-diameter, normal-thickness washer; B is the same diameter but thinner; C is normal diameter with the slightly larger bore and outside diameter of the unfaced form. The form letters were partly defined by steel finish, which doesn't apply to bronze — we make to the dimensions of the form called up. For a large-diameter washer the reference is the ISO 7093-1 large series, or legacy DIN 9021. ISO 7089 corresponds most closely to form A. The drawing will say which; if it just says "washer" we'll confirm the form with you before quoting.
Is DIN 125 the same as ISO 7089? +
ISO 7089 is the modern counterpart to DIN 125A, and ISO 7090 to chamfered DIN 125B. They match up to M36; from M39 the bore and thickness differ at some sizes, so they should not be assumed identical and manufacture follows the standard the drawing calls for.
Do bronze spring washers work? +
They provide some resilience but with a lower spring rate than steel, and they're not a locking device in the engineering sense on any material. If the drawing specifies a spring washer in NAB or SAB we'll make it subject to manufacturing review, using DIN 127 or BS 4464 as a form reference only. Spring washers shouldn't be assumed to provide a particular anti-loosening performance unless the joint design specifies it; where another locking method is required, the drawing or design authority should define it.
Are washers heat treated? +
Not after manufacture. The feedstock is supplied in the condition its material standard requires, and DEF STAN 02-862 Part 2 specifies no further heat treatment for NAB and SAB washers. The material certificate covers the feedstock condition.
Can you make large or odd-sized washers? +
Yes — penny washers to ISO 7093-1 or legacy DIN 9021 pattern, large-bore washers for spigots, shaped and tab washers to drawing. For DEF STAN 02-862 orders the permitted source forms are sheet, strip or bar; other drawing-specific washers may be made from alternative stock forms where the specification permits.
How quickly can you quote? +
Within 24 hours of receiving the drawing or list, usually faster.

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Odd bore, large OD, tab or shaped — send the drawing and we'll quote within 24 hours.

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Location
Christchurch, Dorset BH23 3TG
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