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DIN 985 nyloc nuts

DIN 985 self-locking nuts, commonly known as nyloc nuts, are hex nuts that incorporate an inserted polyamide (nylon) ring to generate friction on the bolt thread and prevent loosening due to vibration. The maximum service temperature of the polyamide insert is 121 °C / 250 °F. These nuts are standardized as prevailing torque type and are mainly manufactured in zinc-plated steel with property class 10, suitable for grade 10.9 bolts.

Dimensions

Section titled “Dimensions”

The values for width across flats and height correspond to property class 10 according to DIN 985 and ISO 10511. Common coarse pitches and the most frequent commercial fine pitches are included.

Nominal size and pitch Width across flats (s) Height (m)
M4 × 0.7 7 mm / 0.276 in 5 mm / 0.197 in
M5 × 0.8 8 mm / 0.315 in 5 mm / 0.197 in
M6 × 1 10 mm / 0.394 in 6 mm / 0.236 in
M8 × 1 13 mm / 0.512 in 8 mm / 0.315 in
M8 × 1.25 13 mm / 0.512 in 8 mm / 0.315 in
M10 × 1 17 mm / 0.669 in 10 mm / 0.394 in
M10 × 1.25 17 mm / 0.669 in 10 mm / 0.394 in
M10 × 1.5 17 mm / 0.669 in 10 mm / 0.394 in
M12 × 1.25 19 mm / 0.748 in 12 mm / 0.472 in
M12 × 1.5 19 mm / 0.748 in 12 mm / 0.472 in
M12 × 1.75 19 mm / 0.748 in 12 mm / 0.472 in
M14 × 1.5 22 mm / 0.866 in 14 mm / 0.551 in
M14 × 2 22 mm / 0.866 in 14 mm / 0.551 in
M16 × 1.5 24 mm / 0.945 in 16 mm / 0.630 in
M16 × 2 24 mm / 0.945 in 16 mm / 0.630 in
M18 × 1.5 27 mm / 1.063 in 18 mm / 0.709 in
M18 × 2.5 27 mm / 1.063 in 18.5 mm / 0.728 in
M20 × 1.5 30 mm / 1.181 in 20 mm / 0.787 in
M20 × 2 30 mm / 1.181 in 20 mm / 0.787 in
M20 × 2.5 30 mm / 1.181 in 20 mm / 0.787 in
M22 × 1.5 32 mm / 1.260 in 22 mm / 0.866 in
M22 × 2.5 32 mm / 1.260 in 22 mm / 0.866 in
M24 × 1.5 36 mm / 1.417 in 24 mm / 0.945 in
M24 × 2 36 mm / 1.417 in 24 mm / 0.945 in
M24 × 3 36 mm / 1.417 in 24 mm / 0.945 in
M27 × 3 41 mm / 1.614 in 27 mm / 1.063 in
M30 × 2 46 mm / 1.811 in 30 mm / 1.181 in
M30 × 3.5 46 mm / 1.811 in 30 mm / 1.181 in
M33 × 3.5 50 mm / 1.969 in 33 mm / 1.299 in
M36 × 3 55 mm / 2.165 in 36 mm / 1.417 in
M36 × 4 55 mm / 2.165 in 36 mm / 1.417 in
M39 × 4 60 mm / 2.362 in 39 mm / 1.535 in
M42 × 4.5 65 mm / 2.559 in 42 mm / 1.654 in
Section titled “Recommended tightening torques”

The values correspond to grade 10.9 bolts with light lubrication (friction coefficient µ ≈ 0.12) and coarse pitch thread, according to common practice for assemblies with DIN 985 self-locking nuts.

Nominal size Pitch (mm) Tightening torque
M4 0.7 3.0 Nm / 2.2 lb‑ft
M5 0.8 6.0 Nm / 4.4 lb‑ft
M6 1.0 10 Nm / 7.4 lb‑ft
M8 1.25 25 Nm / 18 lb‑ft
M10 1.5 49 Nm / 36 lb‑ft
M12 1.75 85 Nm / 63 lb‑ft
M14 2 135 Nm / 100 lb‑ft
M16 2 210 Nm / 155 lb‑ft
M18 2.5 290 Nm / 214 lb‑ft
M20 2.5 410 Nm / 302 lb‑ft
M22 2.5 550 Nm / 406 lb‑ft
M24 3 710 Nm / 524 lb‑ft
M27 3 1050 Nm / 775 lb‑ft
M30 3.5 1450 Nm / 1070 lb‑ft
M33 3.5 1900 Nm / 1401 lb‑ft
M36 4 2500 Nm / 1844 lb‑ft
M39 4 3200 Nm / 2360 lb‑ft
M42 4.5 4000 Nm / 2950 lb‑ft

Drill sizes for clearance hole

Section titled “Drill sizes for clearance hole”

Recommended diameters for medium fit clearance holes (medium series per ISO 273), suitable for assembly with metric thread bolts and DIN 985 nuts.

Nominal bolt size Drill diameter
M4 4.5 mm / 0.177 in
M5 5.5 mm / 0.217 in
M6 6.6 mm / 0.260 in
M8 9.0 mm / 0.354 in
M10 11.0 mm / 0.433 in
M12 13.5 mm / 0.531 in
M14 15.5 mm / 0.610 in
M16 17.5 mm / 0.689 in
M18 20.0 mm / 0.787 in
M20 22.0 mm / 0.866 in
M22 24.0 mm / 0.945 in
M24 26.0 mm / 1.024 in
M27 30.0 mm / 1.181 in
M30 33.0 mm / 1.299 in
M33 36.0 mm / 1.417 in
M36 39.0 mm / 1.535 in
M39 42.0 mm / 1.654 in
M42 45.0 mm / 1.772 in

Allowable loads

Section titled “Allowable loads”

Minimum proof loads correspond to class 10 nuts per ISO 898‑2, assembled with grade 10.9 bolts and coarse pitch thread. The nut must withstand the load without permanent deformation or thread damage.

Nominal size Proof load (kN) Proof load (lbf)
M4 7.0 kN / 1570 lbf
M5 11.5 kN / 2590 lbf
M6 20.1 kN / 4520 lbf
M8 36.6 kN / 8230 lbf
M10 58.0 kN / 13040 lbf
M12 84.3 kN / 18950 lbf
M14 115 kN / 25860 lbf
M16 157 kN / 35300 lbf
M18 192 kN / 43170 lbf
M20 245 kN / 55080 lbf
M22 303 kN / 68120 lbf
M24 353 kN / 79360 lbf
M27 459 kN / 103190 lbf
M30 561 kN / 126120 lbf
M33 694 kN / 156030 lbf
M36 817 kN / 183690 lbf
M39 976 kN / 219430 lbf
M42 1120 kN / 251800 lbf

Equivalences between standards

Section titled “Equivalences between standards”

The DIN 985 nut is equivalent to the international standard ISO 10511 (“Hexagon prevailing-torque type lock nuts with polyamide insert”). In the European scope it is also designated as EN ISO 10511. There is no direct equivalent in the ANSI series, although nylon insert nuts conforming to ANSI/ASME B18.16.6 operate on a similar principle. For applications requiring traceability with American standards, dimensional interchangeability and property class must be verified case by case.

Frequently Asked Questions (FAQ)

Section titled “Frequently Asked Questions (FAQ)”

What is the maximum operating temperature of a DIN 985 nut?

Section titled “What is the maximum operating temperature of a DIN 985 nut?”

The polyamide insert withstands up to 121 °C / 250 °F in continuous service without losing the locking ability.

Can DIN 985 self-locking nuts be reused?

Section titled “Can DIN 985 self-locking nuts be reused?”

Yes, the insert is not damaged during installation and allows several reuses, although the prevailing torque decreases with each assembly. Reuse is not recommended in critical applications where loss of prevailing torque could compromise safety.

Which international standard is equivalent to DIN 985?

Section titled “Which international standard is equivalent to DIN 985?”

The direct equivalent is ISO 10511, which covers the same dimensions and prevailing torque requirements.

What property class do DIN 985 nuts have?

Section titled “What property class do DIN 985 nuts have?”

The standard version corresponds to class 10, designed to be used with grade 10.9 bolts.

Is it necessary to use washers with DIN 985 nuts?

Section titled “Is it necessary to use washers with DIN 985 nuts?”

It is not necessary for the locking function, but flat washers can be used to distribute surface pressure or compensate for irregularities on the bearing surface.

Does the nylon insert get damaged when tightening the nut?

Section titled “Does the nylon insert get damaged when tightening the nut?”

No, the insert deforms elastically over the bolt thread and is not cut. However, if the maximum temperature is exceeded, the nylon may become brittle and lose effectiveness.

Sources Consulted

Section titled “Sources Consulted”