Self Drilling SMS Manufacturer in India | DIN 7504 K Drilling Screws

Overview

DIN 7504 K Drilling Screws (Self Drilling SMS): Manufacturer & Distributor

A self-drilling SMS (sheet metal screw) carries a small drill on its tip. It drills the hole, forms its own mating thread and clamps the parts, all in one run of the screw gun.

Exotic Alloy manufactures self-drilling screws in Mumbai, India, and distributes them to roofing, cladding, HVAC and steel-framing contractors. We supply across India and export to Peru, Latin America, the Gulf and Africa.

One screw, three jobs

The point must be through the steel before the thread arrives, and the joint must fit on the full thread under the head. Those two numbers, the drilling range and the grip length lg, decide the size and the length. For screws into a pre-drilled hole see thread forming and thread cutting screws; inch drill screws with wide heads are on our truss head page.

ISO 15480 DIN 7504 K ISO 10666 No pilot hole 410 & bi-metal

Self-drilling screw at a glance

Also called: Drill screw, self-drilling tapping screw
Heads: ISO 15480 hex washer, 15481 pan, 15482 / 15483 countersunk
Thread: ISO 1478 tapping, ST2.9–ST6.3
Properties: ISO 10666
Drills: 0.7–6 mm steel, by size
Related: Truss head, flange head, sealing washers

An ISO 15480 ST4.8 × 19 hexagon washer head self-drilling screw, the type in our photo. Dimensions from ISO 15480, ISO 1478 and ISO 10666; drill point and lead-in thread drawn schematically.

Specification

Self Drilling Screw Specification

The range we manufacture and supply.

Dimensional standardsISO 15480, 15481, 15482, 15483 (formerly DIN 7504 K, M, O, R)

PropertiesISO 10666 (hardness, drilling, torsional strength)

SizesST2.9, ST3.5, ST4.2, ST4.8, ST5.5, ST6.3

Lengths9.5–50 mm (ISO table); longer to order

ThreadISO 1478 tapping screw thread

Drilling range0.7–6 mm steel, by size

MaterialsCase-hardened carbon steel; 410 stainless; bi-metal A2

Finish & optionsZinc plated; EPDM sealing washer for roofing

CertificationMill certificate; EN 10204 3.1 on request

PackingBoxes of 100 to 1,000; bulk cartons

Head types

Hex Washer, Pan & Countersunk Drilling Screws

Four ISO heads, one thread and one set of drilling ranges.

The four heads at the same scale, size ST4.8. The hexagon washer head has the widest bearing face; the countersunk heads finish flush.

Standard	Head	Replaced	Drive	ST4.8 head mm	Sizes
ISO 15480	Hexagon washer head	DIN 7504 K	Hexagon, s 8	d_c 9.8–10.5, k 3.8–4.3	ST2.9–ST6.3
ISO 15481	Cross recessed pan head	DIN 7504 M	Cross recess No. 2	d_k 9.14–9.5, k 3.4–3.7	ST2.9–ST6.3
ISO 15482	Cross recessed countersunk head, 90°	DIN 7504 O	Cross recess No. 2	d_k 8.9–9.3, k ≤ 2.8	ST2.9–ST6.3
ISO 15483	Cross recessed raised countersunk head	DIN 7504 R	Cross recess No. 2	d_k 8.9–9.3, k ≤ 2.8, raised f ≈ 1.2	ST2.9–ST6.3

All four share the drilling ranges and the grip-length table. Cross recess H = Phillips, Z = Pozidriv. DIN 7504 L was the slotted version of form K.

Dimensions

Self Drilling Screw Dimensions

Size	Pitch P	Washer d_c max / min	Head height k max / min	k_w min wrenching	Washer c min	Across flats s max / min	Across corners e min	Drilling range steel, mm
ST2.9	1.1	6.3 / 5.8	2.8 / 2.5	1.3	0.4	4 / 3.82	4.28	0.7–1.9
ST3.5	1.3	8.3 / 7.6	3.4 / 3	1.5	0.6	5.5 / 5.32	5.96	0.7–2.25
ST4.2	1.4	8.8 / 8.1	4.1 / 3.6	1.8	0.8	7 / 6.78	7.59	1.75–3
ST4.8	1.6	10.5 / 9.8	4.3 / 3.8	2.2	0.9	8 / 7.78	8.71	1.75–4.4
ST5.5	1.8	11 / 10	5.4 / 4.8	2.7	1	8 / 7.78	8.71	1.75–5.25
ST6.3	1.8	13.5 / 12.2	5.9 / 5.3	3.1	1	10 / 9.78	10.95	2–6

ISO 15480:2019, mm (same values as the 1999 edition and as the ISO 7053 hexagon washer head tapping screw). Length L from the bearing face.

Size	Pitch P	Head d_k max / min	Head height k max / min	Crown R ≈	Recess No.	Recess m H / Z, ref.	Drilling range steel, mm
ST2.9	1.1	5.6 / 5.3	2.4 / 2.15	5	1	3 / 3	0.7–1.9
ST3.5	1.3	7 / 6.64	2.6 / 2.35	6	2	3.9 / 4	0.7–2.25
ST4.2	1.4	8 / 7.64	3.1 / 2.8	6.5	2	4.4 / 4.4	1.75–3
ST4.8	1.6	9.5 / 9.14	3.7 / 3.4	8	2	4.9 / 4.8	1.75–4.4
ST5.5	1.8	11 / 10.57	4 / 3.7	9	3	6.4 / 6.2	1.75–5.25
ST6.3	1.8	12 / 11.57	4.6 / 4.3	10	3	6.9 / 6.8	2–6

ISO 15481, mm. m = recess diameter, for reference; H = Phillips, Z = Pozidriv.

Size	Pitch P	Head d_k max / min	Head height k max	Recess No.	Recess m H / Z, ref.	Raised f ISO 15483, ≈	Drilling range steel, mm
ST2.9	1.1	5.5 / 5.2	1.7	1	3.2 / 3.2 (15483: 3.4 / 3.3)	0.7	0.7–1.9
ST3.5	1.3	7.3 / 6.9	2.35	2	4.4 / 4.3 (15483: 4.8 / 4.8)	0.8	0.7–2.25
ST4.2	1.4	8.4 / 8	2.6	2	4.6 / 4.6 (15483: 5.2 / 5.2)	1	1.75–3
ST4.8	1.6	9.3 / 8.9	2.8	2	5.2 / 5.1 (15483: 5.4 / 5.6)	1.2	1.75–4.4
ST5.5	1.8	10.3 / 9.9	3	3	6.6 / 6.5 (15483: 6.7 / 6.6)	1.3	1.75–5.25
ST6.3	1.8	11.3 / 10.9	3.15	3	6.8 / 6.8 (15483: 7.3 / 7.2)	1.4	2–6

ISO 15482 (90° countersunk) and ISO 15483 (raised countersunk, same d_k and k, plus the dome f), mm. Head d_k is the actual diameter, as in the ISO 7050 tapping screw; length L includes the head.

Size	Pitch P mm	Major d₁ max / min	Minor d₂ max / min	Former No.	SAE J78 Type BSD	BSD pitch in mm	BSD major max / min, mm
ST2.9	1.1	2.9 / 2.76	2.18 / 2.08	4	No. 4-24	1.058	2.90 / 2.79
ST3.5	1.3	3.53 / 3.35	2.64 / 2.51	6	No. 6-20	1.270	3.53 / 3.43
ST4.2	1.4	4.22 / 4.04	3.1 / 2.95	8	No. 8-18	1.411	4.22 / 4.09
ST4.8	1.6	4.8 / 4.62	3.58 / 3.43	10	No. 10-16	1.587	4.80 / 4.65
ST5.5	1.8	5.46 / 5.28	4.17 / 3.99	12	No. 12-14	1.814	5.46 / 5.31
ST6.3	1.8	6.25 / 6.03	4.88 / 4.7	14	1/4 in-14	1.814	6.25 / 6.10

ISO 1478 tapping screw thread, mm; former number for information only. SAE J78 values converted from inches by us: the maximum major and the minor diameters are the same; the ISO minimum major diameter is slightly smaller and the ISO pitch is rounded.

Drilling & length

Drilling Range & Grip Length

Size follows from the steel thickness, length from the joint thickness.

Each size drills a band of steel thickness. The bands overlap, so 2 mm steel can take ST3.5 up to ST6.3; the diamond marks the plate each size must drill in the ISO 10666 test.

Steel thickness: add up every steel layer the point must drill and keep the total inside the size’s drilling range.
Joint thickness: everything clamped under the head, steel or not, must not exceed the minimum grip length lg of the length chosen.
Countersunk heads: L and lg are measured from the top of the head; ISO 15482 and 15483 start at 13 mm.
Point and lead-in: L − lg is 6.25 to 12 mm, always longer than the drilling range, so the point is through before the thread bites.

Length L mm	ST2.9	ST3.5	ST4.2	ST4.8	ST5.5	ST6.3
9.5	3.25	2.85	–	–	–	–
13	6.6	6.2	4.3	3.7	–	–
16	9.6	9.2	7.3	5.8	5	–
19	12.5	12.1	10.3	8.7	8	7
22	–	15.1	13.3	11.7	11	10
25	–	18.1	16.3	14.7	14	13
32	–	–	23	21.5	21	20
38	–	–	29	27.5	27	26
45	–	–	–	34.5	34	33
50	–	–	–	39.5	39	38

Minimum grip length lg, mm, ISO 15480:2019 (identical in ISO 15481 to 15483); – = length not standard for that size.

Driving

Drill, Tap, Clamp: Speed, Force & Torque

ST4.8 × 19 in two steel sheets, 1.5 and 2 mm, drawn to scale. Sheets in section; drill point schematic.

Size	Test plate mm	Axial force N	Drill + tap time max, s	Speed rpm, under load	Drilled hole in 1–2 mm plate, min–max	Torsional strength min, N·m
ST2.9	0.7 + 0.7 = 1.4	150	3	1,800–2,500	2.2–2.5 (1 mm)	1.5
ST3.5	1 + 1 = 2	150	4	1,800–2,500	2.7–3 (1 mm)	2.8
ST4.2	1.5 + 1.5 = 3	250	5	1,800–2,500	3.2–3.6 (2 mm)	4.7
ST4.8	2 + 2 = 4	250	7	1,800–2,500	3.7–4.2 (2 mm)	6.9
ST5.5	2 + 3 = 5	350	11	1,000–1,800	4.2–4.8 (2 mm)	10.4
ST6.3	2 + 3 = 5	350	13	1,000–1,800	4.8–5.4 (2 mm)	16.9

ISO 10666:1999, Tables 2 to 4. Test plates: low-carbon steel, C ≤ 0.23 %, 110–165 HV 30. The drilled-hole check is optional, by agreement.

Force: ISO 10666 says the test forces are also guideline values in use; substantially more can break or burn the point.
Speed: the test speeds are a good start for mild steel. One bi-metal maker gives slower speeds into stainless sheet: ST4.8 1,000–1,500 rpm, ST5.5 and ST6.3 600–1,000 rpm.
Clutch: set it well below the minimum torsional strength. The same maker limits driving torque to 4.0 / 6.2 / 10.4 N·m for ST4.8 / 5.5 / 6.3, about 60 % of the ISO minimum.

Problem	Likely cause
Point burns or blunts	Speed too high, or too much force
Screw stalls before the point is through	Steel thicker than the drilling range
Thread strips in thin sheet	Over-driving; set the clutch lower
Sheets jack apart	Parts not held together while drilling
Head snaps off	Torque above the torsional strength

Finder

Self-Drilling Screw Size & Length Finder

Check the drilling range, get the shortest standard length and the driving data.

Screw & joint

Head

Size

Steel to drill, mm

Joint thickness, mm

Steel to drill: all steel layers added up. Joint thickness: everything clamped under the head (for countersunk heads, from the top surface). Drilling ranges and grip lengths lg from ISO 15480 to 15483; force, speed, hole and torsional strength from ISO 10666 (the speed and time are test values). The length is the shortest in the ISO table whose lg is at least the joint thickness.

Result

19

mm length L

1.75–4.4

mm drilling range

Steel to drill:2.5 mm, in range

Grip lg of this length:8.7 mm

Axial force (guide):250 N

Speed (ISO test):1,800–2,500 rpm

Drilled hole:3.7–4.2 mm

Torsional strength, min:6.9 N·m

Drive:8 mm hex, washer Ø10.5

Designation:ISO 15480 - ST4.8 × 19

Materials

Self Drilling Screw Materials & Hardness

Material	Build	Drills steel?	Where
Carbon steel, case hardened	One piece, ISO 10666, zinc plated	Yes, within the drilling range	Indoor and coated work, steel framing, ducts
410 stainless	One piece, martensitic, hardened	Yes	Outdoor steel work, mild exposure
Bi-metal A2	A2 (304) head and body, welded hardened carbon steel tip	Yes	Roofing and façades, stainless sheet
A2 / A4 one piece	Austenitic, not hardenable by heat treatment	Not recommended	Softer materials, where corrosion resistance matters most

Bi-metal build from maker datasheets (Index BIE: AISI 304 body, C1035 tip; Eurotec BiGHTY: A2 with carbon steel tip, ETA-22/0568). Keep at least 2 mm between the parts fixed and the carbon steel tip, per the Index datasheet.

ISO 10666 requirements for carbon steel drilling screws

Property	Requirement (ISO 10666)	Tested by
Material	Case hardening steel or heat-treatable steel	Certificate
Surface hardness	530 HV 0.3 min, after heat treatment	Vickers, ISO 6507-1, preferably on the head
Core hardness	320–400 HV (HV 5 or HV 10 test load, by size)	Vickers on a transverse micro-section
Case depth ST2.9, ST3.5	0.05–0.18 mm	Longitudinal micro-section
Case depth ST4.2 to ST5.5	0.10–0.23 mm	Longitudinal micro-section
Case depth ST6.3	0.15–0.28 mm	Longitudinal micro-section
Microstructure	No ferrite streaks between case and core	Metallography
Tempering	Recommended minimum 330 °C; avoid 275–315 °C	Heat-treatment record
Hydrogen embrittlement	Risk to be managed for electroplated screws	ISO 15330 test; ISO 4042 relief

Carbon steel

Case hardened

Zinc-plated drill screws.

1018 1022

410 stainless

Hardenable

Stainless that still drills steel.

410

Bi-metal A2

304 + hardened tip

A2 corrosion resistance, drills steel.

304 316

Manufacturing

How Our Self Drilling Screws Are Made

1

Wire

Case-hardening or heat-treatable steel, certified by heat.

2

Heading

Hexagon washer, pan or countersunk head cold formed.

3

Point

Drill point and flutes formed on the tip.

4

Thread

ISO 1478 tapping thread rolled.

5

Hardening

Case hardened and tempered, at least 330 °C recommended.

6

Plating

Zinc plating with hydrogen embrittlement relief.

Applications

Where Our Self Drilling Screws Are Used

Roofing & cladding

Profiled sheet to purlins, with an EPDM sealing washer.

Steel framing

Light-gauge studs, tracks and brackets.

HVAC ducting

Duct seams, hangers and plenums.

Solar mounting

Brackets on steel roof sheet and purlins.

Vehicle bodies

Panels and trims on steel frames.

Electrical

Cable trays, boxes and enclosures.

Quality & testing

Self Drilling Screw Inspection & Certification

Check	Method	Applied to
Head, washer, AF	Callipers, gauges to ISO 15480–15483	Every lot
Thread	Major and minor diameter to ISO 1478	Every lot
Surface and core hardness	Vickers, ISO 6507-1	Every heat-treatment lot
Case depth	Micro-section	Every heat-treatment lot
Drilling and screwing-in	ISO 10666 test plate, force and time	Every lot
Torsional strength	ISO 10666 torque to failure	Every lot
Hydrogen embrittlement	ISO 15330	Electroplated lots

Every shipment includes

Mill certificate with heat number
Hardness and drilling test report
Lot number on every box

On request

EN 10204 3.1 certificate
Salt spray test for plated lots
RoHS declaration

FAQ

Self Drilling Screw Questions, Answered

A self-drilling sheet metal screw (SMS) has a drill point at its tip. It drills its own hole in steel sheet, forms the mating thread and clamps the parts in one operation, with no pilot hole. Metric self-drilling screws are standardised in ISO 15480 to ISO 15483, which replaced DIN 7504, with the tapping screw thread of ISO 1478.

A self-tapping screw forms or cuts its own thread but needs a hole drilled first. A self-drilling screw is a tapping screw with a drill point, so it makes the hole as well. The point must pass right through the steel before the thread starts to bite.

ISO 15480 (DIN EN ISO 15480), the hexagon washer head drilling screw, current edition 2019. DIN 7504 M became ISO 15481 (pan head), DIN 7504 O became ISO 15482 (countersunk head) and DIN 7504 R became ISO 15483 (raised countersunk head). The ISO standards dropped the ST3.9 size.

It depends on the size. ISO 15480 gives these drilling ranges for the steel thickness: ST2.9 0.7 to 1.9 mm, ST3.5 0.7 to 2.25 mm, ST4.2 1.75 to 3 mm, ST4.8 1.75 to 4.4 mm, ST5.5 1.75 to 5.25 mm and ST6.3 2 to 6 mm. Where two steel sheets are joined, the point drills both.

The total thickness of the parts clamped must not exceed the minimum grip length lg, the full thread under the head. ISO 15480 lists lg for every length: an ST4.8 x 19 screw has lg 8.7 mm, so it clamps a joint up to 8.7 mm thick. Our finder picks the shortest length that fits.

ISO 10666 tests ST2.9 to ST4.8 at 1,800 to 2,500 rpm and ST5.5 and ST6.3 at 1,000 to 1,800 rpm, with axial forces of 150 N, 250 N or 350 N by size, and says these forces are also guideline values in use. Substantially more force can break or burn the drill point.

A2 and A4 stainless cannot be hardened by heat treatment, so a one-piece A2 drilling screw is meant for softer materials. For steel, use a bi-metal screw, with an A2 head and body and a welded, hardened carbon steel tip, or hardened 410 stainless. One bi-metal maker asks for at least 2 mm between the parts fixed and the carbon steel tip, to avoid contact corrosion.

ST is the tapping screw thread of ISO 1478 and 4.8 is the maximum major diameter in mm, with a pitch of about 1.6 mm. Its former designation is No. 10. Converted to mm, its maximum major diameter and its minor diameter are the same as those of the inch No. 10-16 Type BSD thread of SAE J78.