T Head Screws Manufacturer in India | T-Slot Bolts & T Head Bolts

Overview

T-Slot Bolts & T Head Bolts (DIN 787, ASME B18.5): Manufacturer & Exporter

A T-head bolt has a wide, flat head that sits in a slot and cannot turn. Slide it to where you need it, put the part and a clamp over it, and tighten the nut from the top.

Exotic Alloy manufactures T-head screws and bolts in Mumbai, India, for machine tool, fixture, welding table, press and conveyor builders. We supply across India and export to South Korea, Asia, the Gulf, Europe and North America. Heads are forged, guide faces milled and threads rolled.

Three families

DIN 787 T-slot bolts and DIN 508 T-slot nuts for machine-table T-slots; ASME B18.5 T-head bolts, the inch type with a head twice the bolt diameter long. For DIN 261, 186 and 188 T-head bolts and channel bolts see hammer head bolts.

DIN 787 DIN 508 nuts ASME B18.5 8.8 / 10.9 A2-70 / A4-70

T head screw at a glance

Head: Flat T-head; ASME length 2D
Standards: DIN 787, DIN 508, ASME B18.5
Sizes: Slots 6–36 mm; 1/4–7/8″
Fixing: Slid into a T-slot or turned 90°
Strength: 8.8, 10.9, Grade 5 / 8, A2-70
Related: Hammer head, nuts, washers

ASME B18.5 1/2″-13 × 2″ T-head bolt, drawn to scale at maximum head dimensions: front, end and top views. Thread shown schematically.

Specification

T Head Screw Specification

The range we manufacture and supply.

StandardsDIN 787 T-slot bolts; DIN 508 T-slot nuts; ASME B18.5 T-head bolts (Table 10)

Size rangeT-slots 6–36 mm (M6–M30); nuts M5–M30; inch 1/4–7/8″

ThreadMetric coarse 6g; UNC 2A

LengthsDIN 787 standard lengths 25–250 mm; others to order

Strength10.9 (M6–M12) / 8.8 (M16 up); SAE Grade 5 / 8; A2-70 / A4-70

HeadForged; guide face milled to the slot width (a −0.3 / −0.5)

MaterialsHeat-treated carbon or alloy steel; stainless A2 (304) and A4 (316)

FinishBlackened, zinc plated or plain; stainless passivated

CertificationMill certificate; EN 10204 3.1; hardness and proof load reports

PackingBoxes, clamping kits with nuts and washers

Types

T-Slot Bolt, T-Slot Nut or Inch T-Head Bolt?

Three ways to anchor in a slot.

For a 14 mm slot and its inch equivalent, at the same scale. The DIN 787 bolt and the DIN 508 nut share the same 22 × 8 mm foot; the ASME head is turned across the slot.

Type	Standard	Thread	Best for
T-slot bolt	DIN 787	On the bolt, nut on top	Clamping work and fixtures on machine tables
T-slot nut	DIN 508	In the nut, with a stud or screw	Studs of any length; screws from above
T-head bolt	ASME B18.5	On the bolt, UNC	Inch slots, fixtures, pipe clamps
Hammer head bolt	DIN 261 / 186 / 188	On the bolt	Foundations, channels; see hammer head

Dimensions

T Head Bolt & T-Slot Nut Dimensions

DIN 787 T-slot bolt heads for 6 to 36 mm slots at the same scale, square head from above and profile.

T-slot width	Thread d	a guide −0.3 / −0.5	Head e × e square	Head height k	Lengths l – thread b standard, mm	Property class
6 mm	M6	6	10 −0.5	4 −0.5	25–15, 40–28	10.9
8 mm	M8	8	13 −0.5	6 −0.5	32–22, 50–35	10.9
10 mm	M10	10	15 −0.5	6 −0.5	40–30, 63–45, 100–60	10.9
12 mm	M12	12	18 −0.5	7 −0.5	50–35, 80–55, 125–75	10.9
14 mm	M12	14	22 −0.5	8 −0.5	50–35, 80–55, 125–75, 200–120	10.9
18 mm ^*	M16	18	28 −0.5	10 −0.5	63–45, 100–63, 160–100, 250–150	8.8
22 mm	M20	22	35 −0.5	14 −0.5	80–55, 125–85, 200–125	8.8
28 mm ^*	M24	28	44 −1	18 −1	100–70, 160–110, 250–150	8.8
36 mm	M30	36	54	22	to order	8.8

DIN 787 T-slot bolts, mm; head, lengths and classes as in Ganter / JW Winco catalogue sheets. ^* For 18 and 28 mm slots, the copy of DIN 787:2005 on fasten.it lists smaller heads (25 × 9 and 40 × 16 mm); the values shown match the DIN 508 nuts and the major tooling catalogues. We make either to your drawing.

T-slot width	Thread d	a tongue −0.3 / −0.5	e width −0.5	k foot height	h total height
6 mm	M5	6	10	4	8
8 mm	M6	8	13	6	10
10 mm	M8	10	15	6	12
12 mm	M10	12	18	7	14
14 mm	M12	14	22	8	16
16 mm	M14	16	25	9	18
18 mm	M16	18	28	10	20
20 mm	M18	20	32	12	24
22 mm	M20	22	35	14	28
24 mm	M22	24	40	16	32
28 mm	M24	28	44	18	36
36 mm	M30	36	54	22	44

DIN 508:2002 T-slot nuts, mm. Tongue a fits the slot width; foot e × k sits in the slot’s head space.

Size	UNC	E body dia. max / min	A head length max / min	B head width max / min	H head height max / min	K head radius basic	Thread length 2D + 1/4, L ≤ 6″
1/4″	20	.260 / .237	.500 / .488	.280 / .245	.204 / .172	.438	.750
5/16″	18	.324 / .298	.625 / .609	.342 / .307	.267 / .233	.500	.875
3/8″	16	.388 / .360	.750 / .731	.405 / .368	.331 / .295	.625	1.000
7/16″	14	.452 / .421	.875 / .853	.468 / .431	.394 / .356	–	1.125
1/2″	13	.515 / .483	1.000 / .975	.530 / .492	.458 / .418	.875	1.250
5/8″	11	.642 / .605	1.250 / 1.218	.675 / .616	.585 / .541	1.062	1.500
3/4″	10	.768 / .729	1.500 / 1.462	.800 / .741	.649 / .601	1.250	1.750
7/8″	9	.895 / .852	1.750 / 1.706	.938 / .865	.766 / .724	1.375	2.000

ASME B18.5 Table 10 T-head bolts, inch. Head length A = 2D. K for 7/16″ is not shown: the source value breaks the series, so we confirm it on order.

How it works

How T-Slot Clamping Works

The head pulls up under the slot lips. A T-slot bolt slides in from the end of the slot; an ASME T-head bolt can also be dropped into a plain slot and turned 90°.

When the nut is tightened, the head pulls up against the underside of the slot lips and the clamp presses the work down. The guide neck stops the bolt turning, so only the nut needs a spanner.

The table is usually the weak point: overloading cracks the slot lips. Use the right size for the slot, keep the bolt close to the work, and follow the machine maker’s torque limits.

Do	Avoid
Bolt sized to the slot width	Smaller bolts in big slots
Hardened washer under the nut	Nut straight on the clamp
Bolt close to the work	Long lever to the clamp
Torque within table limits	Extension bars on spanners

Strength

T-Slot Bolt Proof Loads

The bolt’s own limit, before the table’s.

T-slot / thread	Stress area A_s, mm²	8.8 proof load kN	10.9 proof load kN	A2-70 / A4-70 yield load, kN
6 mm / M6	20.1	11.7	16.7	9.0
8 mm / M8	36.6	21.2	30.4	16.5
10 mm / M10	58	33.6	48.1	26.1
12 mm / M12	84.3	48.9	70.0	37.9
14 mm / M12	84.3	48.9	70.0	37.9
18 mm / M16	157	91.1	130.3	70.7
22 mm / M20	245	147.0	203.3	110.2
28 mm / M24	353	211.8	293.0	158.8
36 mm / M30	561	336.6	465.6	252.4

Our calculation: stress area (ISO 898-1) × proof stress 580 MPa (8.8, up to M16) / 600 MPa (8.8, above M16) / 830 MPa (10.9), or × 0.2 % yield strength 450 MPa (A2-70, A4-70, ISO 3506-1).

Size	Stress area A_s, in²	Grade 5 proof load lbf (85 ksi)	Grade 8 proof load lbf (120 ksi)
1/4″-20	0.0318	2,700	3,820
5/16″-18	0.0524	4,460	6,290
3/8″-16	0.0775	6,590	9,300
7/16″-14	0.1063	9,040	12,760
1/2″-13	0.1419	12,060	17,030
5/8″-11	0.2260	19,210	27,120
3/4″-10	0.3345	28,430	40,140
7/8″-9	0.4617	39,250	55,410

Our calculation: A_s = 0.7854 (D − 0.9743 / n)² × SAE J429 proof stress (Grade 5: 85 ksi, Grade 8: 120 ksi).

Calculator

T-Slot Clamp Force Calculator

Pick the slot or inch size and the strength class, enter the tightening torque, and compare the clamp force with the bolt’s proof load.

Bolt & torque

System

Size

Strength class

Torque, N·m

Our estimate: clamp force F = T ÷ (K × d), K = 0.2; utilisation = F ÷ proof load (yield load for stainless). Real preload varies with friction and lubrication; the T-slot table may allow much less than the bolt.

Result

16.7

kN clamp force (est.)

24

% of proof load

Thread / stress area:M12 / 84.3 mm²

Thread stress:198 MPa

Proof (yield) load:70.0 kN

Head:22 × 22 × 8 mm

Materials

T Head Bolt Materials & Finishes

Class / grade	Material	Finish	Best for
10.9	Quenched and tempered alloy steel	Blackened	Machine tables, small T-slots
8.8	Quenched and tempered carbon steel	Blackened, zinc	Machine tables, fixtures
Grade 5 / 8	Medium-carbon / alloy steel (SAE J429)	Plain, zinc, black	Inch T-head bolts
A2-70 / A4-70	Stainless 304 / 316	Plain, passivated	Food, packaging, wet and outdoor use

Alloy steel

10.9 / Grade 8

Highest strength.

4140

Carbon steel

8.8 / Grade 5

Quenched and tempered.

1035 1045

Stainless A2

304, A2-70

As in the photo.

304

Stainless A4

316, A4-70

Chlorides and washdown.

316

Manufacturing

How Our T Head Bolts Are Made

1

Bar

Certified steel or stainless, checked by heat.

2

Forging

T-head forged for an unbroken grain flow.

3

Milling

Guide face milled to the slot width.

4

Thread rolling

6g or 2A threads rolled.

5

Heat treatment

Quenched and tempered to 8.8, 10.9, Grade 5 or 8.

6

Finishing

Blackening, zinc or passivation.

Applications

Where Our T Head Bolts Are Used

Machine tool tables

Milling, drilling and boring work holding.

Fixtures & jigs

Modular fixtures and base plates.

Welding tables

Slotted tables and positioners.

Presses & dies

Die clamping on press beds.

Food & packaging

Stainless T-head bolts in slotted frames.

Pipe clamps

Inch T-head bolts in clamp bodies.

Quality & testing

T Head Bolt Inspection & Certification

Check	Method	Applied to
Guide width a	Snap gauge, −0.3 / −0.5	DIN 787, DIN 508
Head size	Callipers: e, k / A, B, H	Every lot
Hardness	Rockwell / Vickers	Heat-treated lots
Proof load	Tensile machine, ISO 898-1 / SAE J429	Per lot, on request
Thread	6g / 2A ring gauges	Every lot
Material	PMI / chemical analysis	Stainless lots

Every shipment includes

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

On request

EN 10204 3.1 certificate
Proof load test report
Clamping kits with nuts and washers

FAQ

T Head Screw Questions, Answered

A screw or bolt with a T-shaped head that sits in a T-slot or slot, so it cannot turn and can be tightened with a nut from the top. Metric T-slot bolts for machine tables follow DIN 787; inch T-head bolts follow ASME B18.5, with a head twice as long as the bolt diameter.

Choose by slot width. DIN 787 bolts are made for a given slot: a 14 mm slot takes M12, 18 mm takes M16, 22 mm takes M20 and 28 mm takes M24. The guide neck is made 0.3 to 0.5 mm under the slot width so the bolt slides freely without turning.

A DIN 787 T-slot bolt carries the thread on the bolt and is tightened with a nut on top. A DIN 508 T-slot nut is threaded and takes a stud or a screw. For the same slot both have the same foot: 22 mm wide and 8 mm high for a 14 mm slot.

An inch bolt to ASME B18.5 with a rectangular head twice as long as the bolt diameter: a 1/2-13 bolt has a head up to 1.000 in long, 0.530 in wide and 0.458 in high. It slides along a slot and is turned 90 degrees so the long head bears under the slot edges.

Machine-table T-slot bolts are usually heat-treated steel, 10.9 up to M12 and 8.8 above. In class 10.9 an M12 has a proof load of about 70 kN (84.3 mm² × 830 MPa). Stainless A2-70 and A4-70, like the bolts in our photo, suit food, packaging and wet environments.

As an estimate, torque = 0.2 × clamp force × diameter, so 40 N·m on an M12 gives about 16.7 kN of clamp force. The machine table usually limits the safe slot load and torque, so follow the machine maker's figures; our calculator compares the clamp force with the bolt's proof load.

Both have a T-shaped head. DIN 261, DIN 186 and DIN 188 hammer head bolts are general T-head bolts for slots, foundations and channels. DIN 787 T-slot bolts have a guide neck sized to machine-tool table slots, and ASME B18.5 T-head bolts are the inch type with a head twice the bolt diameter long.

Heat-treated steel in classes 8.8 and 10.9, usually blackened; SAE Grade 5 and Grade 8 for inch bolts; and A2-70 or A4-70 stainless steel for corrosive or hygienic places.

Three families

Bolt & torque

Result

Alloy steel

Carbon steel

Stainless A2

Stainless A4

Bar

Forging

Milling

Thread rolling

Heat treatment

Finishing

Machine tool tables

Fixtures & jigs

Welding tables

Presses & dies

Food & packaging

Pipe clamps

Every shipment includes

On request

What is a T head screw?

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