M24 is one of the standard coarse-thread sizes for square head bolts with collar under DIN 478. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M24 Dimensional Row (DIN 478)
| Size | Pitch P (mm) | b1 (mm) | b2 (mm) | c (mm) | da (mm) | dc (mm) | Width across corners e (mm) | Head height k (mm) | r (mm) | Width across flats s (mm) | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M24 | 3 | 54 | 60 | 6 | 26.4 | 36 | 32 | 28 | 0.9 | 24 | 35~180 | DIN 478 |
Spanner & Drive for M24 Square Head Bolts with Collar
Drive geometry for M24 Square Head Bolts with Collar is given by the row above; match the tool to the listed values.
Hole Sizes for M24
| Coarse-thread pitch (ISO 724) | 3 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 26 mm |
| Tapping drill, coarse thread | 21 mm |
Tightening Torque for M24
| Class 8.8 (dry, ~µ 0.125) | ≈ 726 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 1034 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 1210 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 M24
| Tensile stress area As (ISO 724) | 353 mm² |
|---|---|
| Proof load, class 8.8 | 212 kN |
| Proof load, class 10.9 | 293 kN |
| Proof load, class 12.9 | 342 kN |
| Min. ultimate tensile load, class 8.8 | 293 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.
M24 Square Head Bolts with Collar Weight
A steel M24 square head bolts with collar at the listed 35,180 mm length weighs approximately 125,043 g each — about 125,043 kg per 1,000 pieces. Stainless A2/A4 weighs roughly the same (density 7.9–8.0 g/cm³).
Actual weight varies slightly with head form, thread and finish; use this figure for freight estimation only.
Installation Tips for M24 Square Head Bolts with Collar
- At M24 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 M24
For M24, pair with a M24 hex nut (ISO 4032 / DIN 934) and, where used, a M24 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
Custom manufacturing · Made to drawing
Need square head bolts with collar in a size this table does not list?
This page covers M24 square head bolts with collar. Thread size and pitch, length, property class, drive form, head geometry and head marking are all specifiable — the standard part is where it starts, not where it stops. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
