DIN 188 T-Head Bolts with Double Nib
DIN 188 T-head bolts with double nib, M8 to M80 — the T-head bolt whose nibs lock into the underside of a slot so the head cannot twist — with the full collected 14-size table: pitch, the source's three thread-length bands, shank and head geometry and the nib radii.
Last updated: 2026-11
Specifications
DIN 188 is the anti-rotation member of the T-head family. Where DIN 186's plain T-head simply drops into a T-slot, DIN 188 adds two nibs on the underside of the head that engage the slot's undercut groove: the bolt cannot rotate in the slot, so a fixture or clamp bolted to it stays pointed where it was set. That matters on machine tables, clamping rails and mould fixings where several T-bolts carry one strap and any single bolt twisting out of alignment loses its bearing. The collected table covers M8 to M80 — 14 sizes, the large end of the family — with thread pitch P, the source's three thread-length bands b 1 / b 2 / b 3 (with "/" where a band does not apply to that size), shank diameter d s (max / min), head height k, T-slot tongue width n, head length m, radius r 1 ≈ and the nib radius r 2 ① (the source's legend-less ① marker, reproduced verbatim). Materials, property classes and finishes are not printed by the collected specification and stay per RFQ. For the plain T-head form see DIN 186 on this site.
| Standard | DIN 188 — T-head bolts with double nib (anti-rotation head for undercut T-slots) |
|---|---|
| Series | M8 – M80 (14 sizes tabulated) |
| Tabulated geometry | Per size: pitch P, thread-length bands b 1 / b 2 / b 3, shank d s (max / min), head height k (max / min), tongue width n (max / min), head length m (max / min), radius r 1 ≈, nib radius r 2 ① (max) |
| Function | T-head seats in the slot; double nibs engage the slot undercut so the bolt cannot rotate under clamp torque |
| Materials / strength | Not tabulated by the collected specification — per RFQ (property class per clamping load) |
| Size | P — Pitch | b 1 | b 2 | b 3 | d s — max | d s — min | k — max | k — min | n — max | n — min | m — max | m — min | r 1 — ≈ | r 2 ① — max |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M8 | 1.25 | 22 | 28 | / | 8.58 | 7.42 | 5.9 | 5.1 | 8.75 | 7.25 | 18.9 | 17.1 | 0.5 | 1.2 |
| M10 | 1.5 | 26 | 32 | / | 10.58 | 9.42 | 7.45 | 6.55 | 10.75 | 9.25 | 22 | 20 | 0.5 | 1.5 |
| M12 | 1.75 | 30 | 36 | 49 | 12.7 | 11.3 | 8.75 | 7.25 | 12.9 | 11.1 | 27 | 25 | 1 | 1.8 |
| M16 | 2 | 38 | 44 | 57 | 16.7 | 15.3 | 11.4 | 9.6 | 16.9 | 15.1 | 31 | 29 | 1 | 2.4 |
| M20 | 2.5 | 46 | 52 | 65 | 20.84 | 19.16 | 13.9 | 12.1 | 21 | 19 | 37.25 | 34.75 | 1 | 3 |
| M24 | 3 | 54 | 60 | 73 | 24.84 | 23.16 | 15.9 | 14.1 | 25 | 23 | 44.25 | 41.75 | 1.6 | 3.6 |
| M30 | 3.5 | 66 | 72 | 85 | 30.84 | 29.16 | 20 | 18 | 31 | 29 | 55.5 | 52.5 | 1.6 | 4.5 |
| M36 | 4 | 78 | 84 | 97 | 37 | 35 | 24 | 22 | 37.25 | 34.75 | 67.5 | 64.5 | 2 | 5.4 |
| M42 | 4.5 | / | 96 | 109 | 43 | 41 | 27 | 25 | 43.25 | 40.75 | 81.5 | 78.5 | 2 | 6.3 |
| M48 | 5 | / | 108 | 121 | 49 | 47 | 31 | 29 | 49.25 | 46.75 | 89.75 | 86.25 | 2 | 7.2 |
| M56 | 5.5 | / | 124 | 137 | 57.2 | 54.8 | 36.25 | 33.75 | 57.5 | 54.5 | 103.75 | 100.25 | 3 | 8.4 |
| M64 | 6 | / | 130 | 143 | 65.2 | 62.8 | 41.25 | 38.75 | 65.5 | 62.5 | 116.75 | 113.25 | 3 | 9.6 |
| M72 | 6 | / | 156 | 169 | 73.2 | 70.8 | 46.25 | 43.75 | 73.5 | 70.5 | 130 | 126 | 4 | 10.8 |
| M80 | 6 | / | 172 | 185 | 81.2 | 78.8 | 51.25 | 48.75 | 81.5 | 78.5 | 142 | 138 | 4 | 12 |
Materials
- Material and property class specified per RFQ — confirm against clamping load at quotation
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 (DIN 188 T-Head Bolts with Double Nib) 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 1,000–10,000 pieces depending on size. Stock items run 3–7 days. High-strength and custom parts run 15–25 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
When does a T-head bolt need the double-nib head?
When the bolt must stay square to the slot. A plain DIN 186 head is free to rotate, which is fine for a single strap clamp but a problem where two bolts share one strap, where a bracket must stay aligned with the machine axis, or where the assembly is serviced often and each re-set must land in the same place. The nibs engage the slot's undercut, so orientation is fixed for good. Before specifying, confirm the slot itself: nibs need an undercut groove in the T-slot profile, so a slot cut for plain T-heads will not accept DIN 188 — check the tongue width n in the table against the slot and confirm the groove form. For the slot without undercut, DIN 186 remains the part.
What is the MOQ and lead time for this bolt type?
The minimum order quantity is 1,000–10,000 pieces depending on size. Stock items ship in 3–7 days; high-strength and custom parts in 15–25 days. Common diameters in this bolt type are widely stocked; confirm the exact schedule against quantity and size mix at quotation.
Related knowledge
- What Bolt Property Classes 8.8, 10.9 and 12.9 Encode — and When High Strength Stops Being the Right Choice
- Bolt Grade Selection: ISO 898-1 8.8/10.9/12.9 vs ASTM A307 and A325
- 8.8 vs 10.9 vs 12.9 Bolts: Strength, Hardness and Cost — What the Evidence Settles
- Calculating Bolt Preload and Clamp Force: Torque, Friction and Tightening Method
- How to Determine Tightening Torque and Choose a Tightening Method for a Bolted Joint
- Fastener Failure Modes: Which Fatigue, Creep and SCC Controls the Evidence Supports
- Hydrogen Embrittlement in High-Strength Bolts: Which Grades Need Controls, Which Coatings and Baking Schedules Are Acceptable, and What to Require Before the RFQ
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