Tightening Torque Reference are engineering reference manufactured to Calculated (see note); not specified by ISO 898. This page lists the full dimensional range with the key specifications engineers need to select and specify them.
About This Reference
This is an engineering reference table for tightening torque reference based on Calculated (see note); not specified by ISO 898. Use it alongside our fastener catalog when selecting and specifying parts.
Reference Data (Calculated (see note); not specified by ISO 898)
| Size | Torque cl.4.6 (Nm) | Torque cl.8.8 (Nm) | Torque cl.10.9 (Nm) | Torque cl.12.9 (Nm) | Description |
|---|---|---|---|---|---|
| M4 | – | 2.9 | – | 5 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M5 | 2.2 | 5.9 | 8.7 | 10 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M6 | 3.8 | 10 | 15 | 17 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M8 | 9.1 | 24 | 36 | 42 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M10 | 18 | 48 | 71 | 83 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M12 | 32 | 84 | 124 | 145 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M14 | 50 | 134 | 197 | 231 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M16 | 78 | 209 | 306 | 358 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M18 | 108 | 297 | 423 | 495 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M20 | 153 | 420 | 598 | 700 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M22 | 208 | 573 | 816 | 954 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M24 | 264 | 726 | 1034 | 1210 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M27 | 387 | 1064 | 1516 | 1774 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M30 | 525 | 1443 | 2055 | 2405 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
| M36 | 917 | 2523 | 3593 | 4204 | Calculated: preload 65% of proof stress, nut factor K = 0.20 (plain or zinc-plated steel, assembled dry, unlubricated). Lubrication lowers this by roughly a quarter. ISO 898-1 specifies mechanical properties, not tightening torque. An equipment maker's specified torque always governs. |
Manufactured in our own plant
This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.
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01 Cold heading
Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.
Head dimensions and under-head radius checked at set-up and per shift.
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02 Thread rolling
Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.
Go / no-go ring gauges to ISO 965 tolerance class 6g.
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03 Heat treatment
Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.
Core hardness and tensile tested per lot to ISO 898-1.
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04 Surface treatment
Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.
Coating thickness and neutral salt spray hours to ISO 9227.