The M27 size of Socket Head Cap Screws is dimensioned by ISO 4762 / DIN 912. The tables below give the dimensional row from the standard, the drill and spanner sizes that go with it, and the assembly torque per property class. The technical drawing on this page redraws to the exact values selected.
M27 Dimensional Row (ISO 4762 / DIN 912)
| Size | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Hex key s (mm) | Socket depth t min (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M27 | 3.0 | 40.0 | 27.0 | 19.0 | 13.5 | ISO 4762 / DIN 912 |
Spanner & Drive for M27 Socket Head Cap Screws
The hex socket for M27 Socket Head Cap Screws is shown in the spec table — use the matching Allen / hex key (an ISO 2936 hex key set covers the full range). A T-handle key gives the most feel when you are judging preload by hand; anything repeated across a batch wants a torque-controlled driver instead.
Hole Sizes for M27
| Coarse-thread pitch (ISO 724) | 3 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 30 mm |
| Tapping drill, coarse thread | 24 mm |
Tightening Torque for M27
| Class 8.8 (dry, ~µ 0.125) | ≈ 1064 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 1516 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 1774 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 M27
| Tensile stress area As (ISO 724) | 459 mm² |
|---|---|
| Proof load, class 8.8 | 276 kN |
| Proof load, class 10.9 | 381 kN |
| Proof load, class 12.9 | 446 kN |
| Min. ultimate tensile load, class 8.8 | 381 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 M27 Socket Head Cap Screws
- Use a quality Allen key fully seated in the socket — partial engagement is the most common cause of stripped sockets at this size.
- For countersunk and button-head variants, chamfer the through-hole to seat the head flush without preloading the head/shank fillet.
- At M27 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 M27
For M27, pair with a M27 hex nut (ISO 4032 / DIN 934) and, where used, a M27 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
Custom manufacturing · Made to drawing
Need socket head cap screws in a size this table does not list?
This page covers M27 socket head cap screws. 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 warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
