Slotted machine screws — countersunk, pan and cheese head — machined to order to the dimensional requirements of ISO 2009, ISO 1580 and ISO 1207, or legacy BS 4183 where the drawing calls it up, in nickel aluminium bronze (CuAl10Ni5Fe4 — CW307G / CA104) and aluminium silicon bronze (CuAl6Si2Fe — CW301G / CA107) to the applicable drawing or material specification. M2 to M10 metric, smallest sizes subject to manufacturing review; imperial (BA, UNC, UNF) to drawing. Slotted drive only — we don't supply cross-recessed (Pozi / Phillips) forms in these alloys. Supplied with material certification and, where specified, to NES 833 / DEF STAN 02-833 for NAB, NES 834 / DEF STAN 02-834 Pt 2 (superseded by 02-879 Pt 2 Annex D, Sept 2011) for SAB, and the DEF STAN 02-862 Part 2 manufacturing route; 02-862 Table 8 calls up BS 4183 for metric machine screws, with BS EN ISO 1580 and ISO 7045 identified alongside it.
Small screws in these alloys are the ones most often needed in a hurry and in small numbers — a handful of pan-head screws to a drawing for an instrument panel, or SAB countersunk screws for a low-signature fitting. Machined from bar with machined threads. No minimum order quantity.
| Head | Drive | Current standard | Legacy DIN |
|---|---|---|---|
| Countersunk (flat, 90°) | Slotted | ISO 2009 | DIN 963 |
| Pan | Slotted | ISO 1580 | DIN 85 |
| Cheese | Slotted | ISO 1207 | DIN 84 |
The DIN numbers are legacy predecessors; dimensions coincide at most sizes but the standards are not identical, and manufacture follows whichever the drawing calls up. BS 4183:1967 (legacy UK metric machine screws and nuts) is called up by DEF STAN 02-862 Part 2 Table 8 for metric machine screws; where a naval drawing cites BS 4183 we make to it.
Nominal maximum values.
| Thread | Pitch (mm) | Head dia dk (mm) | Head height k (mm) |
|---|---|---|---|
| M2 | 0.4 | 4 | 1.3 |
| M2.5 | 0.45 | 5 | 1.5 |
| M3 | 0.5 | 5.6 | 1.8 |
| M4 | 0.7 | 8 | 2.4 |
| M5 | 0.8 | 9.5 | 3 |
| M6 | 1.0 | 12 | 3.6 |
| M8 | 1.25 | 16 | 4.8 |
| M10 | 1.5 | 20 | 6 |
Non-standard head diameters, thread lengths, drilled heads and imperial (BA / UNC / UNF) to drawing — see Made to Drawing.
CuAl10Ni5Fe4. The higher-strength alloy, with excellent seawater, erosion and cavitation resistance; commonly specified for structural and immersed fastenings. Naval material standard NES 833 / DEF STAN 02-833 Part 2. Relative magnetic permeability typically around 1.4–1.5. Full data, designations and cross-references on the NAB material page.
CuAl6Si2Fe. Good machinability, ductile, and formulated for controlled low magnetic permeability — relative magnetic permeability not exceeding 1.05 (DEF STAN 02-879 Part 2 Annex D, D.2.8; batch-tested to D.4.5) — used for mine countermeasures vessels and other naval low-signature applications. Tighter permeability limits are a drawing or contract requirement and are handled at enquiry stage. Naval material standard NES 834 / DEF STAN 02-834 Part 2, subsequently incorporated into DEF STAN 02-879 Part 2 Annex D. Full data on the SAB material page.
Source-material certification supplied as standard, with traceability to the bar heat maintained through manufacture. Where the drawing calls for DEF STAN 02-862 Part 2, machine screws are machined from bar with machined threads and post-machining stress relief per clause 8.2.4 (NAB) or 8.2.5 (SAB), with heat treatment and stress relief records supplied where required by the drawing, specification or purchase order. Marking, EN 10204 3.1 certification, dimensional inspection reports and CoC as required by the order; EN 10204 3.2 where agreed in advance and supported by the material source and inspection arrangements.
The drawing and specification govern. Alloy designations above are cross-references, not statements of equivalence.
Drilled heads, non-standard lengths, BA or imperial — upload the drawing and we'll quote within 24 hours.
Send us your drawing or spec reference and we'll come back with a price and lead time. No minimum order quantity.