A washer does one of four jobs: spreads load, locks a joint, seals it or fills a gap. The names get mixed up because a spring washer is sold as a lock washer and does very little locking, while a wedge-lock pair or a serrated washer does. The chart names each type with its standard and the size range a stock catalogue holds; the washer for an odd bore, a thick section, a large outside diameter or a material outside the list is stamped or machined.
EKINSUN LTD is a custom parts manufacturer that makes washers to drawing when the stock range stops: a bore and outside diameter no table pairs, a thickness between the standard ones, a large-OD washer in 316L, a copper or PEEK sealing ring of an odd size, a tab washer for a specific nut. The chart below is read against a 2026 stock catalogue; the locking table says which washers hold a joint and which do not; the negative-space table marks the border between buying and making.
"A 30 mm bore, 70 mm outside, 6 mm thick, stainless, twelve pieces. Every catalogue stops at 3 mm thick or 60 outside."
Thick and wide is where washers leave the shelf; odd bores are the other reason.
| Type | Standard | Job | Stock range | Stock materials |
|---|---|---|---|---|
| Flat washer | ISO 7089 / DIN 125 (A / B) | load spreading, surface protection | M1.6–M52 | 304, zinc, black, nickel, hot-dip steel, brass M2–M33, aluminium M5–M24, titanium M3–M20, nylon, PEEK |
| Large (fender) washer | ISO 7093 / DIN 9021 | load spreading on thin or slotted sheet | M3–M24 | 304, zinc steel |
| Small washer | ISO 7092 / DIN 433 | under socket cap screws | M2–M24 | 304 |
| Shim (thin) washer | DIN 988 | gap filling, fine adjustment | M3–M40 | 304 |
| Spring (split) lock washer | DIN 127 (A / B); DIN 7980 for socket screws | take-up of settling; very little locking | M1.6–M36; heavy M6–M20 | 304, zinc and black steel, phosphor bronze M2.5–M20, titanium |
| Tooth lock washer, internal / external | DIN 6797 (J / A) | bites into the face; earth contact through paint | M2.5–M30 | 304, zinc steel |
| Serrated lock washer, internal / external / countersunk | DIN 6798 (J / A / V) | as tooth washers, finer teeth | M2–M33 | 304, zinc steel |
| Double-sided serrated (ribbed) washer | maker series | locks against both faces | M3–M42 | 304, zinc steel |
| Wedge-lock washer pair | DIN 25201-4 (Nord-Lock type) | real locking by cam action under vibration | M3–M42; NL3–NL24 | zinc-flake spring steel 65Mn, 304 / 316 |
| Wave washer | DIN 137 (A curved / B wave) | light spring load, axial take-up, rattle stop | M3–M118 | 304, spring steel |
| Disc spring (Belleville) | DIN 2093 | high spring load in a short stack | M3–M40 | spring steel, 304 |
| Conical spring washer | DIN 6796 | spring load under a bolt head | on request | spring steel |
| Square washer | DIN 436 | timber and channel; cannot rotate | M3–M30 | 304, zinc steel |
| Square taper washer | DIN 434 (8 %, U-sections) / DIN 435 (14 %, I-sections) | brings a bolt square to a sloping flange | M6–M36 | 304, black steel |
| Spherical and conical seat washers | DIN 6319 (C / D / G) | self-aligning seat for a bolt at an angle | M3–M24 | 304, black steel |
| Tab lock washers | DIN 93 (one tab), DIN 432 (external tab), DIN 463 (two tabs) | mechanical locking by a bent tab | M5–M60 | black and plain steel |
| Multi-tab (KM-nut) lock washer | DIN 5406 (MB) | locks a bearing lock nut | M10–M60 | black steel |
| Bonded sealing washer | maker series | seal under a hex head; roofing | 5.5–16 mm | 304 or zinc steel with EPDM |
| Copper and aluminium sealing rings | DIN 7603 | seal on drain plugs and banjo bolts | M5–M36 | annealed copper, aluminium, fibre |
| Cup (finishing) washer | maker series | countersunk screw on a soft face | M3–M6; anodised aluminium M2–M8 | 304, brass, anodised aluminium |
| Earthing (grounding) washer | maker series | cuts through paint for an earth bond | M4–M20 | zinc and yellow-zinc steel, 304 |
| Insulating washers | — | electrical isolation | M1.2–M24 | nylon, PVC, PTFE, PEEK, fibre, mica, ceramic — see plastic fasteners |
| Saddle (curved) washer | maker series | seats a bolt on a tube | D3–D15 | black steel |
| Washer | Under a correctly preloaded bolt | Verdict |
|---|---|---|
| Spring (split) washer DIN 127 | flattens; adds no locking; can help take up settling in soft joints | not a lock |
| Tooth and serrated washers DIN 6797 / 6798 | teeth bite the faces and resist rotation; damage coatings and soft aluminium 6061 | locks on bare steel; wrong on painted or soft faces |
| Wedge-lock pair DIN 25201 | cams increase clamp when the bolt tries to turn | locks; the standard answer for vibration |
| Tab washer DIN 93 / 432 / 463 | a bent tab stops the nut turning | locks mechanically; single use |
| Disc spring DIN 2093 | keeps preload when the joint settles or expands with heat | not a lock; keeps the joint tight |
| Wave washer DIN 137 | light axial spring; takes up play | not a lock |
| Nyloc or all-metal lock nut | prevailing torque in the nut itself | locks; see flange and lock nuts |
The rule: a washer chosen to lock a vibrating joint is a wedge-lock pair, a tab washer or a serrated washer on bare metal; everything else is load spreading or spring take-up. The torque chart gives the preload that makes most joints hold without any lock washer at all.
Stamped or machined? A flat washer in a stock size and thickness is stamped and costs cents. A thick, wide, hardened or odd-bore washer is turned or cut, and the custom washers page explains where the line falls.
| What you need | In the catalogue? | What we make |
|---|---|---|
| Flat, spring, tooth, serrated, wave, square or sealing washer in the stock range, standard thickness | Yes | Buy it from stock. No one-off competes with a stamped washer. |
| Wedge-lock pairs M3–M42, disc springs M3–M40, tab washers M5–M60 | Yes | Stocked; buy it. |
| A flat washer with a bore, outside diameter or thickness no table pairs | No | Turned from bar or cut from plate, from 1 piece — see custom washers. |
| A large-OD or thick washer in 316L, brass, copper, aluminium 6061 or 7075, PEEK or PTFE | No | Machined in the material named. |
| A hardened washer for a 10.9 or 12.9 bolt in a size the stock does not carry | No | Machined from alloy steel and hardened; zinc-flake or black finish. |
| A tab washer, spherical seat or taper washer for a specific nut, angle or flange | No | Machined; tab, seat or taper to the drawing. |
| A sealing washer with a bonded elastomer in an odd size, or a copper ring above M36 | No | Cut or turned; elastomer bonded per batch. |
| A stamped washer of a special shape — D-shape, slotted, keyed, two-hole | No | Stamped to drawing — see custom stamped parts. |
| Material | Designation | Where it fits here |
|---|---|---|
| Stainless 304 | 1.4301 / A2 | the stock washer in every type |
| Stainless 316L | 1.4404 / A4 | stocked in the common flat sizes; machined above |
| Free-machining stainless | 303 / 1.4305 | turned thick washers |
| Spring steel | 65Mn, C67S, C75S | spring, wave, disc and wedge-lock washers; zinc, zinc-flake or black |
| Carbon steel | zinc, yellow-zinc, black, nickel, hot-dip | stock steel washers |
| Hardened alloy steel | 42CrMo4 / 1.7225 | washers under 10.9 and 12.9 bolts |
| Copper, aluminium, fibre | Cu-ETP, Al, vulcanised fibre | sealing rings DIN 7603 |
| Brass, phosphor bronze | CW614N, CuSn6 | electrical washers; non-magnetic spring washers |
| Aluminium 6061 | AlMg1SiCu | light flat washers M5–M24; the face a serrated washer must not bite |
| Aluminium 7075 | AlZn5.5MgCu | anodised cup and finishing washers M2–M8 |
| Nylon, PEEK, PTFE | PA66, PEEK, PTFE | insulating washers |
Barely. Under a properly preloaded bolt a DIN 127 split washer is flat and adds no locking; it can help take up settling in soft or gasketed joints. For a vibrating joint use a wedge-lock pair, a serrated washer on bare metal, a tab washer or a prevailing-torque nut.
DIN 125 (ISO 7089) is the standard flat washer with an outside diameter about twice the bolt size; DIN 9021 (ISO 7093) is the large or fender washer with roughly three times the bolt size, for thin sheet, slots and timber. DIN 433 is the small washer for socket cap screws.
A plain flat washer, or a flange nut with a plain flange. Tooth and serrated washers bite into the face; on aluminium 6061 they embed and the preload relaxes, and on paint they start corrosion.
Yes. Any bore, outside diameter and thickness is turned from bar or cut from plate in 304, 316L, alloy steel, copper, brass, aluminium, PEEK or PTFE, from 1 piece.
EKINSUN LTD is a custom parts manufacturer that machines and stamps washers to any bore, outside diameter, thickness, shape and material, from 1 piece, with a quote within 12 hours.
No list price. Stock sizes are stamped and cost cents; a custom washer is priced by material, section and quantity. A thick 316L washer turned from bar is a few minutes of lathe time; ten thousand stamped D-shape washers are a die plus press time. The quote separates the two.
Bore, outside diameter, thickness, the washer type and its job, material, quantity. A photo of the old washer on a rule works. From 1 piece, quote within 12 hours.
Washers turned, cut or stamped to bore, outside diameter, thickness and material — from 1 piece, quote in 12 hours.