Dimensional data for M18 Thin Hex Nut to GB/T 6172.1 / ISO 4035, 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.
M18 Dimensional Row (GB/T 6172.1 / ISO 4035)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Nut height m (mm) | Reference standard |
|---|---|---|---|---|---|
| M18 | 2.5 | 27.0 | 30.14 | 9.0 | ISO 4035 / GB/T 6172 |
Spanner & Drive for M18 Thin Hex Nut — GB/T 6172.1 / ISO 4035 (Series 055)
M18 Thin Hex Nut — GB/T 6172.1 / ISO 4035 (Series 055) have a width across flats of 27.0 mm — fit a 27.0 mm open-ended spanner or socket. Prefer a 6-point socket over a 12-point: it loads the corners of the 27.0 mm hex far less, which matters on plated heads and on anything that will be re-used. Set preload with a torque wrench rather than by arm.
Tightening Torque for M18
| Class 8.8 (dry, ~µ 0.125) | ≈ 297 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 423 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 495 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 M18
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 M18 Thin Hex Nut — GB/T 6172.1 / ISO 4035 (Series 055)
- Use a 6-point socket where access allows — 12-point sockets are more prone to rounding the corners on smaller sizes.
- A flanged head is its own washer. Adding a flat one under it lifts the serrations clear of the surface they are meant to bite, which is the whole locking mechanism gone.
- At M18 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 M18
Pair M18 with the matching M18 bolt or screw, plus a M18 flat washer where required to distribute load on softer materials.
Custom manufacturing · Made to drawing
Need thin hex nut in a size this table does not list?
This page covers M18 thin hex nut. Thread, height, across-flats, property class, locking feature and flange form can all be varied, including thread sizes the standard series does not run to. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
