Jam Nuts Manufacturer in India | ISO 4035 / DIN 439 Thin Hex Nuts

Overview

ISO 4035 / DIN 439 Thin Hex Nuts (Jam Nuts): Manufacturer & Stockist

A jam nut is a thin nut that locks a full nut on the same thread. Tightened against each other, the two nuts hold a set position on a rod, stud or adjusting screw, or keep a nut from turning where it cannot be fully tightened.

Exotic Alloy manufactures and stocks jam nuts in Mumbai, India, for machine builders, maintenance teams, structural and plant contractors and fastener distributors. We supply across India and export to Nigeria, West Africa, the Gulf and South-East Asia.

A locking nut, not a load nut

Thin nuts have a reduced load capacity and are not designed to resist thread stripping, so they always work with a regular nut (hex nuts) or a heavy hex nut. For a single nut that locks itself see nylock jam nuts.

ISO 4035 DIN 439-2 Hex jam Heavy hex jam Class 04 / 05

Jam nuts at a glance

Metric: ISO 4035:2023 (style 0), M1.6–M64
Older metric: DIN 439-2 (withdrawn)
Inch: ASME B18.2.2 hex and heavy hex jam nuts
Height: 0.5 D from M8 up
Classes: 04, 05 (ISO 898-2)
Fitting: Thin nut first, full nut on top
Related: Hex nuts, coupling nuts, threaded rods

A locked pair on an M12 bolt, half section to scale. The 6 mm thin nut bears on the part, the 10.8 mm regular nut is tightened onto it; both take the same 18 mm spanner.

Specification

Jam Nut Specification

The range we manufacture and stock.

StandardsISO 4035, DIN 439-2, ASME B18.2.2; fine thread ISO 8675

Metric sizesM1.6 to M64, coarse thread 6H

Inch sizes1/4 to 4 in, hex jam and heavy hex jam

Steel classes04, 05 (ISO 898-2, style 0); ASTM A563 for inch

Other materialsStainless A2 and A4 (ISO 3506-2), brass, Monel, duplex

FinishPlain, zinc plated, zinc flake, hot-dip galvanized

Product gradeA to M16, B above (ISO 4035)

MarkingClass 04 or 05 and the maker's mark

CertificationEN 10204 3.1; 3.2 on request

SupplyLoose, or in pairs with matching full nuts

ISO 4035

ISO 4035 Thin Hex Nut Dimensions

Style 0, coarse thread, mm.

Size	Pitch P	s max / min	e min	m max / min	d_w min	ISO 4032 m max regular nut	≈ kg / 1000 steel
M1.6	0.35	3.2 / 3.02	3.41	1 / 0.75	2.54	1.3	0.06
M2	0.4	4 / 3.82	4.32	1.2 / 0.95	3.34	1.6	0.11
M2.5	0.45	5 / 4.82	5.45	1.6 / 1.35	4.34	2	0.22
M3	0.5	5.5 / 5.32	6.01	1.8 / 1.55	4.84	2.4	0.29
M3.5	0.6	6 / 5.82	6.58	2 / 1.75	5.34	2.8	0.37
M4	0.7	7 / 6.78	7.66	2.2 / 1.95	6.2	3.2	0.56
M5	0.8	8 / 7.78	8.79	2.7 / 2.45	7.2	4.7	0.83
M6	1	10 / 9.78	11.05	3.2 / 2.9	8.88	5.2	1.59
M7	1	11 / 10.73	12.12	3.7 / 3.4	9.63	6.5	2.09
M8	1.25	13 / 12.73	14.38	4 / 3.7	11.63	6.8	3.27
M10	1.5	16 / 15.73	17.77	5 / 4.7	14.63	8.4	6.10
M12	1.75	18 / 17.73	20.03	6 / 5.7	16.63	10.8	8.70
M14	2	21 / 20.67	23.36	7 / 6.42	19.64	12.8	13.8
M16	2	24 / 23.67	26.75	8 / 7.42	22.49	14.8	20.4
M18	2.5	27 / 26.16	29.56	9 / 8.42	24.85	15.8	29.2
M20	2.5	30 / 29.16	32.95	10 / 9.1	27.7	18	39.7
M22	2.5	34 / 33	37.29	11 / 9.9	31.35	19.4	57.5
M24	3	36 / 35	39.55	12 / 10.9	33.25	21.5	68.7
M27	3	41 / 40	45.2	13.5 / 12.4	38	23.8	101
M30	3.5	46 / 45	50.85	15 / 13.9	42.75	25.6	143
M33	3.5	50 / 49	55.37	16.5 / 15.4	46.55	28.7	182
M36	4	55 / 53.8	60.79	18 / 16.9	51.11	31	243
M39	4	60 / 58.8	66.44	19.5 / 18.2	55.86	33.4	314
M42	4.5	65 / 63.1	71.3	21 / 19.7	59.95	34	401
M45	4.5	70 / 68.1	76.95	22.5 / 21.2	64.7	36	498
M48	5	75 / 73.1	82.6	24 / 22.7	69.45	38	614
M52	5	80 / 78.1	88.25	26 / 24.7	74.2	42	742
M56	5.5	85 / 82.8	93.56	28 / 26.7	78.66	45	890
M60	5.5	90 / 87.8	99.21	30 / 28.7	83.41	48	1051
M64	6	95 / 92.8	104.86	32 / 30.4	88.16	51	1235

ISO 4035:2023; s, e and m as in the 2012 edition, d_w now to two decimals, M7 new. Same hexagon (s, e) as the ISO 4032 regular nut, so one spanner fits both. Mass: our calculation for steel (hexagon minus the thread hole), within 8 % of the DIN 439 table.

Thin, regular, high. In these sizes the jam nut is 50 to 72 % of the height of the full nut.

DIN 439

DIN 439-2 vs ISO 4035

Size	Spanner s ISO 4035	Spanner s DIN 439-2	Height m max both	DIN 439-2 kg / 1000
M1.6	3.2	3.2	1	0.06
M2	4	4	1.2	0.11
M2.5	5	5	1.6	0.22
M3	5.5	5.5	1.8	0.29
M3.5	6	6	2	0.37
M4	7	7	2.2	0.57
M5	8	8	2.7	0.83
M6	10	10	3.2	1.6
M8	13	13	4	3.2
M10	16	17	5	7.2
M12	18	19	6	10.4
M14	21	22	7	15.9
M16	24	24	8	20.5
M18	27	27	9	29.6
M20	30	30	10	40.2
M22	34	32	11	48.3
M24	36	36	12	69.5
M27	41	41	13.5	101
M30	46	46	15	139
M33	50	50	16.5	183
M36	55	55	18	244
M39	60	60	19.5	316
M42	65	65	21	403
M45	70	70	22.5	500
M48	75	75	24	617
M52	80	80	26	755

DIN 439-2:1987 (chamfered thin nuts), withdrawn and replaced by ISO 4035; highlighted spanner sizes differ. Heights are identical. The M6 mass is 1.5 or 1.6 kg / 1000 depending on the source; our calculation gives 1.6.

Inch

ASME B18.2.2 Hex & Heavy Hex Jam Nuts

Size	Hex jam nut F max / H1 max / min, in	Heavy hex jam nut F max / H1 basic / max / min, in	Hex nut H max for comparison, in
1/4	0.438 / 0.163 / 0.150	0.500 / 11/64 / 0.188 / 0.156	0.226
5/16	0.500 / 0.195 / 0.180	0.562 / 13/64 / 0.220 / 0.186	0.273
3/8	0.563 / 0.227 / 0.210	0.688 / 15/64 / 0.252 / 0.216	0.337
7/16	0.688 / 0.260 / 0.240	0.750 / 17/64 / 0.285 / 0.247	0.385
1/2	0.750 / 0.323 / 0.302	0.875 / 19/64 / 0.317 / 0.277	0.448
9/16	0.875 / 0.324 / 0.301	0.938 / 21/64 / 0.349 / 0.307	0.496
5/8	0.938 / 0.387 / 0.363	1.062 / 23/64 / 0.381 / 0.337	0.559
3/4	1.125 / 0.446 / 0.398	1.250 / 27/64 / 0.446 / 0.398	0.665
7/8	1.312 / 0.510 / 0.458	1.438 / 31/64 / 0.510 / 0.458	0.776
1	1.500 / 0.575 / 0.519	1.625 / 35/64 / 0.575 / 0.519	0.887
1-1/8	1.688 / 0.639 / 0.579	1.812 / 39/64 / 0.639 / 0.579	0.999
1-1/4	1.875 / 0.751 / 0.687	2.000 / 23/32 / 0.751 / 0.687	1.094
1-3/8	2.062 / 0.815 / 0.747	2.188 / 25/32 / 0.815 / 0.747	1.206
1-1/2	2.250 / 0.880 / 0.808	2.375 / 27/32 / 0.880 / 0.808	1.317
1-5/8	2.430 / 0.944 / 0.868	2.562 / 29/32 / 0.944 / 0.868	1.416
1-3/4	2.625 / 1.009 / 0.929	2.750 / 31/32 / 1.009 / 0.929	1.540
1-7/8	2.813 / 1.073 / 0.989	2.938 / 1-1/32 / 1.073 / 0.989	1.651
2	3.000 / 1.138 / 1.050	3.125 / 1-3/32 / 1.138 / 1.050	1.763
2-1/4	3.375 / 1.267 / 1.155	3.500 / 1-13/64 / 1.251 / 1.155	1.986
2-1/2	3.750 / 1.427 / 1.401	3.875 / 1-29/64 / 1.505 / 1.401	2.209
2-3/4	4.125 / 1.556 / 1.522	4.250 / 1-37/64 / 1.634 / 1.522	2.431
3	4.500 / 1.685 / 1.643	4.625 / 1-45/64 / 1.763 / 1.643	2.654
3-1/4	4.875 / 1.814 / 1.748	5.000 / 1-13/16 / 1.876 / 1.748	2.877
3-1/2	5.250 / 1.943 / 1.870	5.375 / 1-15/16 / 2.006 / 1.870	3.100
3-3/4	5.625 / 2.072 / 1.990	5.750 / 2-1/16 / 2.134 / 1.990	3.322
4	6.000 / 2.201 / 2.112	6.125 / 2-3/16 / 2.264 / 2.112	3.545

ASME B18.2.2-2022 Tables 5 and 11, inch. Jam nuts share the across-flats size of the matching hex or heavy hex nut. Material specifications: ASTM A563, F594 (stainless), F467 (non-ferrous).

Fitting

How to Fit a Jam Nut Correctly

Thin nut next to the part, full nut on top. Two spanners in the last step.

The right way

Run the thin nut down and tighten it against the part, with less torque than the full nut will get.
Run the full nut down onto the thin nut.
Hold the thin nut with one spanner and tighten the full nut against it with another.
The full nut now carries the load; the thin nut locks it.

Common mistakes

Putting the thin nut on top: it then has to carry a load it is not designed for.
Using a thin nut alone where the joint must carry load.
Tightening the full nut without holding the thin nut, so the thin nut turns with it.

Finder

Jam Nut Finder: Size, Pair Height & Load

Pick the standard and size; get the jam nut, its partner nut and the height of the pair.

Jam nut & order

Standard

Size

Pairs

Class / material

Dimensions from the tables on this page. Partner nut: ISO 4032 for ISO 4035, DIN 934 for DIN 439, ASME hex or heavy hex nut for inch. Proof loads from ISO 898-2:2012 Table 4 (M5 to M39). Mass: our calculation for steel.

Result

6

mm jam nut height (min 5.7)

16.8

mm pair height, with ISO 4032 nut

Spanner:18 mm (both nuts)

Partner nut height:10.8 mm

Proof load, jam nut:42.2 kN

Mass, jam nut:8.7 g each, 4.3 kg

Designation:500 pcs Hexagon thin nut ISO 4035 – M12 – 05

Strength

Thin Nut Classes 04 & 05 and Proof Loads

Why the full nut must carry the load. A thin nut is proof tested at roughly 40 to 60 % of the load of a class 8 regular nut of the same size.

Size	Class 04 kN	Class 05 kN	Regular nut class 8 kN, for comparison
M5	5.4	7.1	12.1
M6	7.6	10.0	17.2
M7	11.0	14.5	24.7
M8	13.9	18.3	31.8
M10	22.0	29.0	50.5
M12	32.0	42.2	74.2
M14	43.7	57.5	101.2
M16	59.7	78.5	138.2
M18	73.0	96.0	176.6
M20	93.1	122.5	225.4
M22	115.1	151.5	278.8
M24	134.1	176.5	324.8
M27	174.4	229.5	422.3
M30	213.2	280.5	516.1
M33	263.7	347.0	638.5
M36	310.5	408.5	751.6
M39	370.9	488.0	897.9

ISO 898-2:2012 Table 4, coarse thread; the thin nut must carry the load on a hardened mandrel without stripping or cracking. ISO 898-2 was revised in 2022; we test to the edition on your order.

The two classes

04: carbon steel, M5 to M39.
05: carbon steel, quenched and tempered, M5 to M39.
The leading 0 marks the reduced loadability of a thin nut.
The second digit is 1/100 of the nominal stress under proof load on a hardened mandrel, in MPa.

Carbon steel

04 · 05 · A563

Plain, zinc or galvanized.

1035 1045

Stainless

A2 · A4

As in the photo.

304 316

Special alloys

Brass · Monel · duplex

Marine and chemical duty.

Brass Monel 400 2205

Manufacturing

How Our Jam Nuts Are Made

1

Wire / bar

Steel or alloy certified by heat.

2

Form

Hexagon and both chamfers, cold forged or machined.

3

Tap

6H or 2B, matched to the partner nut.

4

Heat treat

Quenched and tempered for class 05.

5

Finish

Zinc, zinc flake, galvanized or plain.

6

Pack

Loose or paired with full nuts.

Applications

Where Our Jam Nuts Are Used

Adjusting screws

Locking set screws, stops and levelling feet.

Threaded rods

Hangers, tie rods and turnbuckles.

Machinery

Pivots, linkages and belt tensioners.

Vehicles

Tie rod ends and adjusters.

Structures

Hanger and anchor rods held at a set height.

Electrical

Terminal studs and panel fixings.

Quality & testing

Jam Nut Inspection & Certification

Check	Method	Applied to
Thread	GO / NOT GO plug gauges, 6H or 2B	Every lot
s, e, m	Calipers, height gauge	Every lot
Proof load	Hardened mandrel, ISO 898-2 Table 4	Class 04 / 05 lots
Hardness	Vickers, Brinell or Rockwell	Every lot
Stainless	To ISO 3506-2; PMI	A2 / A4 lots
Coating	Thickness gauge	Coated lots

Every shipment includes

EN 10204 3.1 certificate
Class and maker's mark on the nuts
Lot number on every box

On request

EN 10204 3.2 with third-party inspection
Jam nuts paired with full nuts
Dimensional and coating reports

FAQ

Jam Nut Questions, Answered

A thin nut tightened against a second, full-height nut so the two lock each other on the thread. ISO 4035 thin nuts are half as high as the thread diameter from M8 upward: an M12 jam nut is 6 mm high, against 10.8 mm for a regular ISO 4032 nut.

The thin nut goes on first and is tightened against the part; then the full nut is run down and tightened against the thin nut while the thin nut is held with a second spanner. ISO 898-2 describes the assembly this way, so the full nut carries the bolt load.

No. Thin nuts have a reduced load capacity and are not designed to resist thread stripping, so ISO 898-2 and ISO 4035 say to use them together with a regular or high nut.

They are the classes for thin nuts in ISO 898-2. The 0 marks the reduced loadability; the 4 or 5 is one hundredth of the nominal stress under proof load on a hardened test mandrel. An M12 class 04 thin nut is proof tested at 32 kN and a class 05 at 42.2 kN, against 74.2 kN for a class 8 regular nut.

18 mm for an ISO 4035 nut, the same as an ISO 4032 nut, and 19 mm for a DIN 439 nut. The two standards also differ at M10 (16 and 17 mm), M14 (21 and 22 mm) and M22 (34 and 32 mm); heights are the same.

To ASME B18.2.2 a 1/2-13 hex jam nut is 0.302 to 0.323 in thick and 3/4 in across flats; a heavy hex jam nut is 0.277 to 0.317 in thick and 7/8 in across flats. A regular 1/2 in hex nut is 0.427 to 0.448 in thick.

Nearly. DIN 439-2 was replaced by ISO 4035; the heights are identical, but the spanner sizes differ at M10, M12, M14 and M22, as with DIN 934 and ISO 4032.

To lock adjusting screws, threaded rods, tie rods, turnbuckles and studs at a set position, and as a lock on a nut that cannot be fully tightened, for example on a pivot or a set length.