ISO 14581 Hexalobular Socket Countersunk Head Screws
ISO 14581 countersunk head screws with hexalobular (TORX-style) socket, M2 to M10 — the flush high-torque machine screw — with the full collected 9-size table: theoretical and actual head diameters, socket size and engagement depth, thread-end lash and thread lengths.
Last updated: 2026-11
Specifications
ISO 14581 is the countersunk counterpart of the ISO 14583 pan head: a 90-degree flush head driven by a hexalobular socket — the TORX-style recess that transfers markedly higher torque than cross-recess Phillips without cam-out. The head seats into a countersink so the dome-free top sits flush with the surface, and the hexalobular drive keeps that flushness repeatable under power tools where a Phillips would cam-out and mar the countersink. The collected table runs M2 to M10 and draws the distinction the standard is built on: the head diameter d k appears twice — the theoretical sharp-corner value (max) the drawing layout needs, and the actual head value (max=nominal / min) the finished part carries — alongside head height k max, the Socket No. (T6 through T50), the A driving dimension (Ref.), engagement depths t max/min, the x thread-end lash limit and thread lengths b from 25 to 38 mm. The pan head counterpart is ISO 14583 on this site; the cross-recessed countersunk forms are ISO 7046-1/-2. Materials, property classes and finishes are not printed by the collected specification and follow the drawing callout.
| Standard | ISO 14581 — countersunk flat head screws with hexalobular socket (TORX-style recess) |
|---|---|
| Series | M2 – M10 (9 sizes tabulated) |
| Tabulated geometry | Per size: pitch P, head diameter d k (theoretical max; actual max=nominal size / min), head height k max, thread-end lash x, socket size (T6–T50), socket driving dimension A (Ref.), engagement depth t max/min, thread length b |
| Head / drive form | 90° countersunk flat head (flush-seated), hexalobular socket drive — high torque without cam-out |
| Family note | Countersunk counterpart of hexalobular pan head ISO 14583; cross-recessed countersunk equivalents ISO 7046-1/-2 |
| Materials / strength | Not tabulated by the collected specification — per RFQ (property class and finish per drawing callout) |
| Nominal thread | P — Pitch | d k — theoretical — max | d k — actual — max=nominal size | d k — actual — min | k — max | x — max | Socket No. | A — Ref. | t — max | t — min | Length of Thread b |
|---|---|---|---|---|---|---|---|---|---|---|---|
| M2 | 0.4 | 4.4 | 3.8 | 3.5 | 1.2 | 1 | T6 | 1.75 | 0.64 | 0.51 | 25 |
| M2.5 | 0.45 | 5.5 | 4.7 | 4.4 | 1.5 | 1.1 | T8 | 2.4 | 0.79 | 0.66 | 25 |
| M3 | 0.5 | 6.3 | 5.5 | 5.2 | 1.65 | 1.25 | T10 | 2.8 | 0.83 | 0.7 | 25 |
| (M3.5) | 0.6 | 8.2 | 7.3 | 6.94 | 2.35 | 1.5 | T15 | 3.35 | 1.32 | 1.16 | 25 |
| M4 | 0.7 | 9.4 | 8.4 | 8.04 | 2.7 | 1.75 | T20 | 3.95 | 1.53 | 1.14 | 38 |
| M5 | 0.8 | 10.4 | 9.3 | 8.94 | 2.7 | 2 | T25 | 4.5 | 1.51 | 1.12 | 38 |
| M6 | 1 | 12.6 | 11.3 | 10.87 | 3.3 | 2.5 | T30 | 5.6 | 1.78 | 1.39 | 38 |
| M8 | 1.25 | 17.3 | 15.8 | 15.37 | 4.65 | 3.2 | T45 | 7.95 | 2.54 | 2.15 | 38 |
| M10 | 1.5 | 20 | 18.3 | 17.78 | 5 | 3.8 | T50 | 8.95 | 2.8 | 2.41 | 38 |
Materials
- Material, property class and finish specified per RFQ — the collected specification table covers geometry only
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (ISO 14581 Hexalobular Socket Countersunk Head Screws) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
Why does the table print the head diameter twice?
Because a countersunk head has two diameters that are both real. The theoretical value is measured to the sharp corner where the cone would meet the surface — the figure your countersink layout and flushness check work from. The actual value is the finished head's diameter after the corner is rounded, which is what you measure on the part. Comparing a formed part against the theoretical column fails every time; use the actual max/min band for inspection and the theoretical figure for hole and countersink design.
What is the MOQ and lead time for these screws?
Minimum order quantity is 10,000 pieces per item. Stocked sizes ship in 3–7 days; non-stock diameters, lengths or finishes are quoted with a confirmed schedule. Common sizes in this designation are widely stocked — confirm the exact schedule against quantity and size mix at quotation.
Related knowledge
- Thread-Forming vs Thread-Cutting vs Thread-Rolling Self-Tapping Screws: What the Evidence Settles on Base Material
- Screw Family Selection by Base Material: Wood, Machine and Self-Tapping Threads, Engagement and Coating
- Hex Bolts vs Socket Head Cap Screws: What the Evidence Settles on Strength, Clearance and Cost
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support