Self-Tapping Screws

A self-tapping screw cuts its thread and produces swarf. The hole is drilled first but not tapped. Removing the tapping operation is why this is the common choice for sheet metal and plastics assembly.

Specification options

Available options. Actual capability is confirmed on enquiry.
Volume range	M1.0 – M5.0
Maximum size	M16
Standards	DIN 7971 · DIN 7972 · DIN 7981 · DIN 7982 · ISO 1478 · ISO 7049 · JIS B 1122
Materials	see Materials
Finishes	see Finishes
Minimum order	From 10,000 pcs, depending on the part

Head styles

Pan

Countersunk

Oval

Hexwasher

Button

Drive types

Phillips

Pozidriv

Torx

Hexext

Slotted

When to choose each →

Choosing the thread

Type AB / Agimlet point

Good lead-in, enters easily; suits thin sheet and softer materials.
Type Bblunt point

Thread starts at the end face. Used where material is thicker or the point must not protrude.
Type 17slotted point

A slot at the tip forms a cutting edge — better swarf clearance and lower driving torque. Common in timber and thicker sections.

Where it most often goes wrong

Each of these causes scrapped lots or rework on the floor. None of them is theoretical.

Pilot hole wrong. Too small strips the head or snaps the point; too large gives no pull-out strength. The correct diameter depends on material and thickness — it is not one number, and it is the single most common cause of failure.

Using 304 stainless into hard material. A2 is too soft: the cutting edge deforms before the material does. For harder substrates use martensitic SUS410, which can be hardened by heat treatment. The cost is noticeably lower corrosion resistance.

Nowhere for the swarf to go. Cutting produces chips. A blind hole needs a chip reservoir, or the swarf packs the bottom and lifts the screw — it reads as seated when it is not.

How length is measured

One rule covers it: if the head sinks into the work, measure overall; if it stays on the surface, measure under the head.

Three head styles compared: countersunk measured overall, oval to the cone intersection, pan under the head — The red line is the datum. Heads that sink into the work are measured overall; heads that stay on the surface are measured under the head.

Measurement datum by head style
Head style	Datum	Why
Countersunk (flat)	Overall length	The head sits flush in the countersink, so it counts
Oval (raised countersunk)	Overall to the head diameter	The cone sinks, the dome stays proud; measure to where they meet
Pan / round	Under head	The head stays entirely on the surface
Button	Under head	Same
Hex / hex washer	Under head	Same
Socket head cap	Under head	Same

Full explanation →　 Where the standards stop at this size →　 Tolerance stack-up and the screw →

Enquiries

Self-Tapping Screws come in a lot of combinations. Tell us the item, size, material, finish, annual usage and application, and we will come back on feasibility and lead time. A drawing or a sample is fastest — quoting against the real part saves a great deal of guessing.

Volume range M1.0 – M5.0, standard fasteners up to M16. Minimum order From 10,000 pcs, depending on the part.

sales@screwkingtw.com