Machine Screws

A machine screw's thread is formed beforehand, and so is the mating internal thread — a tapped hole or a nut. Nominal diameter and pitch have to match exactly for it to engage at all, which is the fundamental difference from the self-tapping family.

Specification options

Available options. Actual capability is confirmed on enquiry.
Volume range	M1.0 – M5.0
Maximum size	M16
Standards	DIN 84 · DIN 963 · DIN 965 · DIN 7985 · ISO 1207 · ISO 2009 · ISO 7045 · ISO 7046 · JIS B 1101 · JIS B 1111
Materials	see Materials
Finishes	see Finishes
Minimum order	From 10,000 pcs, depending on the part

Head styles

Pan

Countersunk

Oval

Cheese

Button

Hex

Drive types

Phillips

Pozidriv

Slotted

Hexsocket

Torx

Phillips

When to choose each →

Choosing the thread

Coarse

The default. Larger pitch, more tolerant of hole condition, less prone to stripping over repeated assembly.
Fine

Greater effective section at the same outside diameter and marginally better self-locking; suits thin walls or fine preload adjustment. The trade-off is sensitivity to hole accuracy and easier stripping.

Where it most often goes wrong

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

Mixing metric and imperial. M3 and #4-40 look alike. Forcing one into the other destroys both threads, and it is invisible at goods-in — you find out halfway down the hole.

Phillips driven with a Pozidriv bit, or the reverse. The crosses look identical; Pozidriv has four additional fine ribs in the recess. The wrong bit cams out, and on an automated line that becomes a whole lot of rejects.

Pitch not specified. M3×0.5 and M3×0.35 share an outside diameter. A purchase order that says only “M3” has not specified the part.

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

Machine 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