M4 Stainless Knurled Countersunk Blind Rivet Nuts dimensions to Trade series (Bollhoff RIVKLE stainless-steel series): nut height 0.9 mm, coarse thread pitch 0.7 mm. Tighten to approximately 2.9 Nm at property class 8.8 in a dry, as-supplied condition.
- Nut height
- 0.9 mm
- Coarse thread pitch
- 0.7 mm
- Tightening torque (class 8.8)
- 2.9 Nm
Figures are nominal values from the governing standard. Confirm against the tolerance class for your application before machining or ordering.
The M4 size of Stainless Knurled Countersunk Blind Rivet Nuts is dimensioned by Trade series (Bollhoff RIVKLE stainless-steel series). The table below gives the dimensional row from the standard, followed by the drive and the installation notes for this type.
M4 Dimensional Row (Trade series (Bollhoff RIVKLE stainless-steel series))
| Thread size | Body diameter (mm) | Body length (mm) | Grip range (mm) | Hole diameter (mm) | Countersink thickness (mm) | End options |
|---|
| M4 | 9.3 | 8.0 | 1.3~2.0 | 6.0 | 0.9 | open / closed |
Spanner & Drive for M4 Stainless Knurled Countersunk Blind Rivet Nuts
Drive geometry for M4 Stainless Knurled Countersunk Blind Rivet Nuts is given by the row above; match the tool to the listed values.
Tightening Torque for M4
| Class 8.8 (dry, ~µ 0.125) | ≈ 2.9 Nm |
|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 4.1 Nm |
|---|
| Class 12.9 (dry, ~µ 0.125) | ≈ 4.9 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 M4
| Tensile stress area As (ISO 898-1) | 8.78 mm² |
|---|
| Proof load, class 8.8 | 5.1 kN |
|---|
| Proof load, class 10.9 | 7.3 kN |
|---|
| Proof load, class 12.9 | 8.5 kN |
|---|
| Min. ultimate tensile, class 8.8 | 7 kN |
|---|
Proof load = stress area × proof stress per ISO 898-1. Design joints so the working preload stays below the proof load of the selected class.
Installation Tips for M4 Stainless Knurled Countersunk Blind Rivet Nuts
- At M4 the joint is sensitive to over-torque — use a torque-limiting driver and check the head doesn't bury into a softer counterpart.
When to Step Up or Down from M4
When the joint preload approaches the proof load of M4 class 8.8, step up to M5 class 8.8 (or move to M4 class 10.9). When the joint is over-specified, M3 often saves weight and cost without losing the safety margin.
Applications & Industries for M4 Stainless Knurled Countersunk Blind Rivet Nuts
Where Stainless Knurled Countersunk Blind Rivet Nuts are used, and what decides the specification in each case. Stocked from M3 to M4.
Industries that specify Stainless Knurled Countersunk Blind Rivet Nuts
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Automotive interiors
Flush threaded mounting points behind trim and finished panels.
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Laboratory equipment
Stainless blind threads in cleanable covers and guards.
-
Electronic housings
Serviceable threads in thin sheet where insert rotation must be controlled.
-
Precision fabrication
Countersunk blind inserts that remain below the finished panel face.
-
Automotive & transport
Vibration-prone joints where the locking type is specified on the drawing.
-
Maintenance & MRO
Replacements matched to the existing bolt class, thread and finish.
Typical applications
- leaving a countersunk insert flush with the parent sheet
- resisting rotation through a knurled blind body
- adding a reusable thread without reaching the rear of the panel
- matching countersink depth, hole diameter and grip range
- locking an adjustment so it cannot drift
- joints re-torqued at a service interval
Service conditions to specify against
- Marine and coastal
- Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
- High load
- Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
- Match the class
- A nut below the bolt property class strips before the bolt reaches its own limit — pair class 8 nuts with 8.8 bolts, class 10 with 10.9.
Where to use something else
- Do not leave the countersink shallow; a proud flange can interfere with the mating panel or finish.
Full application guide: where Stainless Knurled Countersunk Blind Rivet Nuts are used, how to specify them, and the cases they are wrong for
