M8 is one of the standard coarse-thread sizes for flanged button head socket screws under Trade series (flanged button head). The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M8 Dimensional Row (Trade series (flanged button head))
| Thread size | Pitch (mm) | Flange diameter dc (mm) | Head height k (mm) | Hex socket s (mm) | Bearing area vs plain button | Common length range (mm) | Property class |
|---|---|---|---|---|---|---|---|
| M8 | 1.25 | 18.0 | 4.40 | 5.0 | approx. 2.0x | 12~60 | 10.9 |
Spanner & Drive for M8 Flanged Button Head Socket Screws
The hex socket for M8 Flanged Button Head Socket 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 M8
| Coarse-thread pitch (ISO 724) | 1.25 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 9 mm |
| Tapping drill, coarse thread | 6.75 mm |
Tightening Torque for M8
| Class 8.8 (dry, ~µ 0.125) | ≈ 24 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 36 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 42 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 M8
This is a reduced-height head. The head, not the thread, limits what the screw will carry — ISO 7380-1 caps a button head at roughly 80% of the thread's capacity — so the thread's proof load overstates the assembly. Size the joint on the head, or use a cap screw where the full class strength is needed.
M8 Flanged Button Head Socket Screws Weight
A steel M8 flanged button head socket screws at the listed 1,260 mm length weighs approximately 2,517 g each — about 2,517 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 M8 Flanged Button Head Socket 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.
Mating Parts for M8
For M8, pair with a M8 hex nut (ISO 4032 / DIN 934) and, where used, a M8 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
Custom manufacturing · Made to drawing
Need flanged button head socket screws in a size this table does not list?
This page covers M8 flanged button head socket screws. Head form and drive can be specified to the assembly rather than to a standard: a larger bearing face, a security drive, or a socket sized for the tool already on the bench. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
