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DIN 9021

Plain washer,large series

Superseded by ISO 7093-1 (2000) · Still sold as DIN 9021 · Sizes M2.5–M36
DIN 9021 washer cut in half, with the thickness hDIN 9021 washer cut in half, with the thickness h
Side view, in section
DIN 9021 washer seen from its face, with the hole d1 and the large outer diameter d2DIN 9021 washer seen from its face, with the hole d1 and the large outer diameter d2
Face view
Sized1 (mm, nom.)d2 (mm, nom.)h (mm, nom.)
M4
4.3012.001.00
M5
5.3015.001.00
M6
6.4018.001.60
M8
8.4024.002.00
M10
10.5030.002.50
M12
13.0037.003.00
M16
17.0050.003.00
M20
21.0060.004.00

Values per ISO 7093-1:2000.Differs from DIN 9021

Verified data

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Calculators that use this standard: Tightening torque and screw loads · Bolted joint configurator

About DIN 9021

What it is

The plain washer of the large series: its outside diameter is about three times the thread. An M10 has the same 10.5 mm hole as DIN 125, but a 30 mm outside diameter and 2.5 mm thickness (DIN 125: 20 and 2 mm).

Where it is used

Under heads and nuts on soft or thin parts (wood, plastics, sheet metal) and over large or slotted clearance holes, where a normal washer would sink in or slip through, from M2.5 to M36.

DIN or ISO

ISO 7093-1 replaced DIN 9021. Most sizes are the same; four differ: the M5 is 1 mm thick in ISO and 1.2 mm in DIN, and M18, M20 and M24 have a hole 1 mm smaller in ISO (M20: 21 mm against 22). ISO 7093-1 starts at M3.

Typical mistakes

  • Ordering by the outside diameter. The 30 mm washer is the M10 one.
  • Trusting the washer alone over a large clearance hole. ISO 7093-1 asks to check its thickness there: a thin washer bends over a wide hole.
  • Using a soft washer under a high-strength screw. ISO 7093-1 suits its 200 HV class to screws up to 8.8 and its 300 HV class to 10.9.
  • Mixing DIN and ISO washers of M18, M20 or M24: the hole differs by 1 mm.

References