M20 Serrated Flange Lock Nuts dimensions to DIN 6923: width across flats (spanner size) 30 mm, nut height 3 mm, coarse thread pitch 2.5 mm. Tighten to approximately 420 Nm at property class 8.8 in a dry, as-supplied condition.
- Width across flats (spanner size)
- 30 mm
- Nut height
- 3 mm
- Coarse thread pitch
- 2.5 mm
- Tightening torque (class 8.8)
- 420 Nm
Figures are nominal values from the governing standard. Confirm against the tolerance class for your application before machining or ordering.
Dimensional data for M20 Serrated Flange Lock Nuts to DIN 6923, with the drive and the installation notes for this type.
Values are taken from the governing standard rather than from a general machine-thread table, because this type is not selected on one.
M20 Dimensional Row (DIN 6923)
| Thread size | Pitch (mm) | Across flats s (mm) | Flange diameter dc (mm) | Total height m (mm) | Flange thickness c (mm) | Reference standard |
|---|
| M20 | 2.5 | 30 | 42.8 | 20.0 | 3.0 | DIN 6923 |
Spanner & Drive for M20 Serrated Flange Lock Nuts
Drive geometry for M20 Serrated Flange Lock Nuts is given by the row above; match the tool to the listed values.
Tightening Torque for M20
| Class 8.8 (dry, ~µ 0.125) | ≈ 420 Nm |
|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 598 Nm |
|---|
| Class 12.9 (dry, ~µ 0.125) | ≈ 700 Nm |
|---|
Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class.
Proof Load & Strength for M20
Nuts are graded to ISO 898-2 by the proof load the nut itself will hold (classes 04, 05, 5, 6, 8, 10 and 12), not by the 8.8 / 10.9 / 12.9 scale used for bolts. A class-8 nut is the correct mate for a class-8.8 bolt, and the joint is designed on the bolt, so no bolt-tension figure is quoted here.
Installation Tips for M20 Serrated Flange Lock Nuts
- At M20 the stretch in the bolt becomes the controlling factor — for critical joints, use angle-controlled or stretch-controlled tightening instead of pure torque.
Mating Parts for M20
Pair M20 with the matching M20 bolt or screw, plus a M20 flat washer where required to distribute load on softer materials.
Custom manufacturing · Made to drawing
Need serrated flange lock nuts in a size this table does not list?
This page covers M20 serrated flange lock nuts. Thread size is the obvious variable and rarely the interesting one — height for clearance, across-flats for the tool already in the cell, and the locking feature for the vibration actually present. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
Custom nut manufacturingSend a drawing
Applications & Industries for M20 Serrated Flange Lock Nuts
Serrated Flange Lock Nuts are bought for a small number of well-defined jobs. These are the ones we ship them for. Stocked from M4 to M20.
Industries that specify Serrated Flange Lock Nuts
-
Building services
Threaded rod, channel and suspension assemblies.
-
Machine building & OEM
The clamping counter-face on studs and bolts throughout an assembly.
-
Steel fabrication
Bolted structural and frame connections.
-
Automotive & transport
Vibration-prone joints where the locking type is specified on the drawing.
-
Maintenance & MRO
Replacements matched to the existing bolt class, thread and finish.
Typical applications
- locking an adjustment so it cannot drift
- joints re-torqued at a service interval
- completing a bolted joint on a stud, rod or bolt
Service conditions to specify against
- Marine and coastal
- Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
- High load
- Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
- Vibration
- Specified where cyclic load would loosen a plain nut or screw — rotating plant, rail, mobile equipment and anything that is not re-torqued in service.
- Match the class
- A nut below the bolt property class strips before the bolt reaches its own limit — pair class 8 nuts with 8.8 bolts, class 10 with 10.9.
Full application guide: where Serrated Flange Lock Nuts are used, how to specify them, and the cases they are wrong for
