M14 Hex Flange Bolts are manufactured to ISO 1665 / DIN 6921 with a coarse thread pitch of 2 mm. This page lists the controlling dimensions for the M14 size — head geometry, width across flats, matching spanner size — together with the clearance hole, tapping drill and tightening torque used at assembly.
M14 Dimensional Row (ISO 1665 / DIN 6921)
| Size | Pitch (mm) | Flange diameter dc (mm) | Head height k (mm) | Width across flats s (mm) | Reference standard |
|---|---|---|---|---|---|
| M14 | 2.0 | 29.9 | 12.3 | 21.0 | ISO 1665 / DIN 6921 |
Spanner & Drive for M14 Hex Flange Bolts
M14 Hex Flange Bolts have a width across flats of 21.0 mm — fit a 21.0 mm open-ended spanner or socket. Prefer a 6-point socket over a 12-point: it loads the corners of the 21.0 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.
Hole Sizes for M14
| Coarse-thread pitch (ISO 724) | 2 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 15.5 mm |
| Tapping drill, coarse thread | 12 mm |
Tightening Torque for M14
| Class 8.8 (dry, ~µ 0.125) | ≈ 134 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 197 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 231 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 M14
| Tensile stress area As (ISO 724) | 115 mm² |
|---|---|
| Proof load, class 8.8 | 67 kN |
| Proof load, class 10.9 | 96 kN |
| Proof load, class 12.9 | 112 kN |
| Min. ultimate tensile load, class 8.8 | 92 kN |
Proof load = tensile stress area × the proof stress Sp of the class, per ISO 898-1 — Sp is a lower figure than the yield stress Rp0.2 and the two are not interchangeable. The stress area is computed from this size's own diameter and pitch, so a fine-pitch designation gives the fine-pitch figure. Design the joint so the working preload stays below the proof load of the class selected.
Installation Tips for M14 Hex Flange Bolts
- 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.
Mating Parts for M14
For M14, pair with a M14 hex nut (ISO 4032 / DIN 934) and, where used, a M14 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
Custom manufacturing · Made to drawing
Need hex flange bolts in a size this table does not list?
This page covers M14 hex flange bolts. Where the standard stops, the drawing takes over: fine pitches, left-hand threads, partial threading, and property classes above the catalogued grade where material and heat treatment allow. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
