Button Head Screws Manufacturer in India

Overview

ISO 7380 Button Screws & Button Head Socket Screws: Manufacturer & Exporter

A button head screw gives you the hex socket drive of a cap screw under a low, rounded head that sits neatly on the surface. There is no counterbore to machine and no sharp edge to catch hands or cables.

Exotic Alloy manufactures button head screws in Mumbai, India, for machine builders, enclosure and automation makers, aluminium profile systems and equipment manufacturers. We stock across India and export to Turkey, the Gulf, Europe and Africa. Heads and sockets are cold formed in one blow, and threads are rolled.

Low head, lighter duty

The head is only 0.55 times the thread diameter high, against 1 times for an ISO 4762 cap screw. The socket is shallower and takes a smaller key. That makes button heads ideal for covers, guards and panels, but they are rated as screws with reduced loadability. For highly loaded joints use socket cap screws.

ISO 7380-1 ISO 7380-2 flanged ASME B18.3 inch A2 / A4 stainless 10.9 alloy steel

Button head screw at a glance

Head: Low dome, k = 0.55 d (metric)
Drive: Hexagon socket, one key size below a cap screw (M3–M12)
Length: Measured from under the head
Loadability: Reduced: not for high-tension joints
Grades: A2-70, A4-70, 10.9; ASTM F835 / F879 (inch)
Related: Socket cap screws, flange head screws, Allen bolts

ISO 7380-1 M6 × 16, drawn to scale from the standard’s maximum dimensions. The 4 mm socket is only 2.08 mm deep and leaves a wall of 0.74 mm under it, which is why the head is rated for lighter loads than a cap screw.

Specification

Button Head Screw Specification

The range we manufacture and supply.

StandardsISO 7380-1 (button head); ISO 7380-2 (with collar); ASME B18.3 (inch button head socket cap screws)

Size rangeM3–M16; No. 4 to 5/8″

LengthsM3 5–30 mm up to M16 20–120 mm; specials to drawing

ThreadMetric coarse 6g, fine to order; UNC / UNF (inch)

GradesA2-70, A4-70 (ISO 3506-1); 10.9 alloy steel, 8.8 and 12.9 to order; ASTM F835 and F879 (inch)

FinishPassivated stainless; black oxide, zinc plated or zinc flake alloy steel

DriveHexagon socket; hexalobular socket to drawing

MarkingMaterial or class and maker’s mark on the head where its size allows

CertificationMill certificate; EN 10204 3.1; PMI for stainless

PackingBoxes of 100 to 1000, bulk cartons, kits to order

Head types

Button Head vs Socket Cap, Low Head & Countersunk

Five hex socket heads for the same M6 thread: how far each stands above the part and what key it takes.

M6 heads at the same scale, from the standard tables (ISO 4762, DIN 7984, ISO 7380-1, ISO 7380-2, ISO 10642). The button head stands about half as high as the cap screw, without a counterbore or a countersink.

Size	Head height k button / cap / low head	Hex key s button / cap	Socket depth t button / cap	Wall under socket w button / cap	Head dia. button / cap
M3	1.65 / 3 / 2	2 / 2.5	1.04 / 1.3	0.2 / 1.15	5.7 / 5.5
M4	2.2 / 4 / 2.8	2.5 / 3	1.3 / 2	0.3 / 1.4	7.6 / 7
M5	2.75 / 5 / 3.5	3 / 4	1.56 / 2.5	0.38 / 1.9	9.5 / 8.5
M6	3.3 / 6 / 4	4 / 5	2.08 / 3	0.74 / 2.3	10.5 / 10
M8	4.4 / 8 / 5	5 / 6	2.6 / 4	1.05 / 3.3	14 / 13
M10	5.5 / 10 / 6	6 / 8	3.12 / 5	1.45 / 4	17.5 / 16
M12	6.6 / 12 / 7	8 / 10	4.16 / 6	1.63 / 4.8	21 / 18
M16	8.8 / 16 / 9	10 / 14	5.2 / 8	2.25 / 6.8	28 / 24

Maximum head dimensions and minimum t and w, mm. Button: ISO 7380-1; cap: ISO 4762; low head: DIN 7984.

Dimensions

Button Head Screw Dimensions & Weights

The eight ISO 7380-1 sizes at the same scale, top view and profile, with head diameter d_k max and hex key.

Size	P	d_k max / min	k max / min	s key	e min	t min	w min	Lengths
M3	0.5	5.7 / 5.4	1.65 / 1.4	2	2.3	1.04	0.2	5–30
M4	0.7	7.6 / 7.24	2.2 / 1.95	2.5	2.87	1.3	0.3	6–50
M5	0.8	9.5 / 9.14	2.75 / 2.5	3	3.44	1.56	0.38	6–60
M6	1	10.5 / 10.07	3.3 / 3	4	4.58	2.08	0.74	6–60
M8	1.25	14 / 13.57	4.4 / 4.1	5	5.72	2.6	1.05	10–90
M10	1.5	17.5 / 17.07	5.5 / 5.2	6	6.86	3.12	1.45	12–120
M12	1.75	21 / 20.48	6.6 / 6.24	8	9.15	4.16	1.63	16–120
M16	2	28 / 27.48	8.8 / 8.44	10	11.43	5.2	2.25	20–120

ISO 7380-1:2011 hexagon socket button head screws, mm. P pitch; d_k head diameter; k head height; s hex key; e socket across corners; t socket depth; w wall under the socket. Lengths are the commercial range of the weight table.

Size	d_c flange dia. max	d_k dome dia. max	k head height max	c flange min	s hex key	t socket depth min
M3	6.9	5.2	1.65	0.7	2	1.04
M4	9.4	7.2	2.2	0.8	2.5	1.3
M5	11.8	8.8	2.75	1	3	1.56
M6	13.6	10	3.3	1.2	4	2.08
M8	17.8	13.2	4.4	1.5	5	2.6
M10	21.9	16.5	5.5	2	6	3.1
M12	26	19.4	6.6	2.4	8	4.16
M16	34	26	8.8	2.8	10	5.2

ISO 7380-2 hexagon socket button head screws with collar, mm. See also flange head screws.

Size	Head dia. D max / min, in	Head height H max / min, in	Hex key in	Key engagement T min, in	Max. standard length in
No. 4	0.213 / 0.201	0.059 / 0.051	1/16″	0.035	0.50
No. 5	0.238 / 0.226	0.066 / 0.055	5/64″	0.044	0.50
No. 6	0.262 / 0.250	0.073 / 0.063	5/64″	0.044	0.63
No. 8	0.312 / 0.298	0.087 / 0.077	3/32″	0.052	0.75
No. 10	0.361 / 0.347	0.101 / 0.091	1/8″	0.070	1.00
1/4″	0.437 / 0.419	0.132 / 0.122	5/32″	0.087	1.00
5/16″	0.547 / 0.527	0.166 / 0.152	3/16″	0.105	1.00
3/8″	0.656 / 0.636	0.199 / 0.185	7/32″	0.122	1.25
1/2″	0.875 / 0.851	0.265 / 0.245	5/16″	0.175	2.00
5/8″	1.000 / 0.970	0.331 / 0.311	3/8″	0.210	2.00

ASME B18.3 button head socket cap screws, inches. Longer screws are made to order.

Length l, mm	M3	M4	M5	M6	M8	M10	M12	M16
5	0.38	–	–	–	–	–	–	–
6	0.42	0.86	1.56	2.25	–	–	–	–
8	0.5	1	1.8	2.58	–	–	–	–
10	0.59	1.15	2.03	2.92	6.01	–	–	–
12	0.67	1.29	2.26	3.25	6.63	11.8	–	–
14	0.75	1.43	2.49	3.58	7.24	12.8	–	–
16	0.83	1.57	2.73	3.92	7.82	13.8	21.2	–
18	0.91	1.72	2.96	4.25	8.46	14.8	22.6	–
20	0.99	1.86	3.19	4.58	9.07	15.7	24	50.6
22	1.07	2	3.42	4.92	9.68	16.7	25.5	53.2
25	1.2	2.22	3.77	5.42	10.6	18.1	27.6	57.1
30	1.4	2.58	4.35	6.25	12.12	20.6	31.1	63.6
35	–	2.94	4.93	7.08	13.65	23	34.6	70.1
40	–	3.3	5.51	7.92	15.18	25.4	38.1	76.6
45	–	3.66	6.09	8.75	16.7	27.9	41.6	83.1
50	–	4.02	6.67	9.58	18.23	30.3	45.2	89.6
55	–	–	7.25	10.42	19.76	32.7	48.7	96.1
60	–	–	7.83	11.25	21.29	35.1	52.2	102.6
70	–	–	–	–	24.35	40	59.2	115.6
80	–	–	–	–	27.4	44.9	66.2	128.6
90	–	–	–	–	30.45	49.7	73.3	141.6
100	–	–	–	–	–	54.6	80.3	154.6
110	–	–	–	–	–	59.5	87.3	167.6
120	–	–	–	–	–	64.4	94.3	180.6

ISO 7380-1 in steel, kg per 1000 pieces. We have left out the published M6 70–100 mm and M8 100 mm values, which do not follow the weight-per-length step of the rest of the table; ask us for those sizes.

Strength

How Strong Are Button Head Screws?

A 10.9 button head screw is made from the same heat-treated steel as any 10.9 screw; the limit is the head. With a head only 0.55 d high, a shallow socket and a thin wall under it, ISO 7380 classes these as screws with reduced loadability: they may not reach the minimum tensile load of their property class.

ISO 898-1 lets steel screws with reduced loadability carry a leading zero in the marking, such as 010.9. The smaller key and shallow socket also limit the tightening torque: forcing the key can round the socket before the screw is fully loaded.

Joint	Button head?
Covers, guards, panels	Yes, the main use
Aluminium profile frames	Yes, with T-nuts
Thin sheet, large holes	Yes, ISO 7380-2 flanged
Machine parts under high preload	No: ISO 4762 cap screw
Structural or safety-critical joints	No: full-load bolts or cap screws
Frequent dismantling	Better with a cap screw (deeper socket)

Installation

Fitting Button Head Screws Correctly

Plain clearance hole

No counterbore or countersink: drill the ISO 273 clearance hole, for example 6.6 mm for M6.

Right key, fully home

Use a good-quality key of the exact size, pushed to the bottom of the shallow socket.

Moderate torque

Tighten less than a cap screw of the same size; avoid high-torque impact drivers.

Enough thread

Length = clamped thickness + thread engagement; the finder below picks the next listed length.

Stainless into stainless

Use an anti-seize compound and turn slowly to avoid galling.

Large or slotted holes

Choose the flanged ISO 7380-2 head instead of adding a washer.

Calculator

Button Head Screw Length & Weight Finder

Enter the size, what you are clamping and what the screw goes into. The finder picks the next listed ISO 7380-1 length and works out the weight of your order.

Joint & order

Size

Clamped thickness, mm

Screw goes into

Material

Quantity, pcs

Engagement figures are common rules of thumb; tapped holes must be deeper than the engagement. Steel weights are from the ISO 7380-1 table; stainless weights are our estimate from density (A2 × 1.01, A4 × 1.02).

Result

16

mm length

3.92

kg per 1000

Length needed:16 mm

Weight per screw:3.92 g

Order weight:3.92 kg

Pieces per kg:255

Hex key:4 mm (cap screw 5 mm)

Clearance hole:6.6 mm

Materials

Button Head Screw Materials & Grades

Grade	Standard	Typical finish	Use
A2-70 (304)	ISO 3506-1	Passivated	Indoor and general outdoor
A4-70 (316)	ISO 3506-1	Passivated	Marine, food, chemicals, washdown
10.9 alloy steel	ISO 898-1	Black oxide, zinc or zinc flake	Machines and frames, dry or coated
Alloy steel (inch)	ASTM F835	Black oxide or zinc	Inch machinery
Stainless (inch)	ASTM F879	Passivated	Inch equipment, corrosive service

Stainless A2

304

The grade in the photo; the everyday choice.

304 304L

Stainless A4

316

For salt, chlorides and cleaning chemicals.

316 316L

Chromium-moly steel

10.9 · 12.9

Quenched and tempered socket screws.

4137 4140

Boron steel

8.8 · 10.9

Hardenable steel for smaller sizes.

15B35H 1035

Manufacturing

How Our Button Head Screws Are Made

1

Wire

Stainless or alloy steel wire, certified by heat.

2

Cold heading

Dome and hex socket formed together in the heading die.

3

Thread rolling

Threads rolled, not cut, for an unbroken grain flow.

4

Heat treatment

Quench and temper for 10.9; stainless stays as formed.

5

Finishing

Passivation, black oxide, zinc or zinc flake.

6

Inspection

Socket gauged, head and thread checked, lot sealed.

Applications

Where Our Button Head Screws Are Used

Machine guards

Covers and guards with a smooth, snag-free head.

Aluminium profile frames

Brackets and panels fixed with T-nuts in slotted profiles.

Automation & robotics

Grippers, sensors and cable guides where space is tight.

Enclosures & electronics

Panels, racks and housings with a neat finish.

Bicycles & motorsport

Light, low-profile fixings on fairings and accessories.

Food & pharma equipment

A4 stainless with a rounded head that is easy to wipe down.

Quality & testing

Button Head Screw Inspection & Certification

Check	Method	Applied to
Head diameter & height	Callipers: d_k, k	Every lot
Hex socket	GO / NO-GO hex gauge; depth t	Every lot
Thread	Ring gauges, 6g	Every lot
Length	Measured under the head	Every lot
Hardness	ISO 898-1 test	Every heat-treatment lot (steel)
Material	PMI	Stainless lots

Every shipment includes

Mill certificate with heat number
Dimensional report
Lot number on every box

On request

EN 10204 3.1 certificate
Salt spray test for coated lots
Count-checked kits and labels

FAQ

Button Head Screw Questions, Answered

A button head screw is a hexagon socket screw with a low, rounded head. Metric sizes are made to ISO 7380-1 and inch sizes to ASME B18.3. The smooth dome has no sharp edges to catch hands, cables or clothing, and the head is wider and much lower than a socket head cap screw.

The button head is much lower and slightly wider. For M6, an ISO 7380-1 button head is 3.3 mm high and 10.5 mm across, against 6 mm and 10 mm for an ISO 4762 socket head cap screw. The button head also takes a smaller key (4 mm against 5 mm) in a shallower socket (2.08 mm against 3 mm), so it cannot be tightened as hard.

Yes. Because of the low head and shallow socket, ISO 7380 button head screws are screws with reduced loadability: they may not reach the minimum tensile load of the property class they are made from. ISO 898-1 lets steel screws with reduced loadability carry a leading zero in the marking, for example 010.9. Use button heads for covers, guards and panels, and socket head cap screws for highly loaded joints.

For ISO 7380-1: M3 takes a 2 mm key, M4 2.5 mm, M5 3 mm, M6 4 mm, M8 5 mm, M10 6 mm, M12 8 mm and M16 10 mm. From M3 to M12 that is one key size smaller than a socket head cap screw of the same thread. For inch button heads to ASME B18.3: No. 10 takes 1/8 in, 1/4 in takes 5/32 in, 5/16 in takes 3/16 in and 3/8 in takes 7/32 in.

ISO 7380-2 adds a collar, a thin flange under the dome. For M6 the flange is 13.6 mm across against 10.5 mm for the plain ISO 7380-1 head, so it spreads the load and covers larger or slotted holes without a washer. Head height and key size are the same.

From the underside of the head (the bearing face) to the end of the screw. The dome is not included, so an M6 × 16 button head screw is 16 mm under the head and about 19.3 mm overall.

In steel, an ISO 7380-1 M6 × 16 weighs about 3.92 kg per 1000 pieces, M8 × 20 about 9.07 kg and M10 × 25 about 18.1 kg. Austenitic stainless steel is about 1 to 2 percent denser, so A2 and A4 screws weigh slightly more. Our length and weight finder works out the weight for any listed size and quantity.

Metric button head screws are usually made in stainless steel A2-70 (304) or A4-70 (316) and in 10.9 alloy steel, black or zinc flake coated. Inch button heads are made to ASTM F835 (alloy steel) and ASTM F879 (stainless steel). Use A4 near the sea, in food plants and where cleaning chemicals are used.