DIN 551 Slotted set screws
DIN 551 is the slotted, headless set screw with a flat point: the end is a plain flat face with a small chamfer. It presses squarely against the mating part instead of biting into it, so it is the point engineers reach for when a screw must be adjusted often, or when it bears on a hardened shaft or a soft insert that should not be marked. Definite Metal manufactures DIN 551 in CW614N brass from M1.6 to M12, with custom lengths on request. Part of our brass grub screws range.
What the Flat Point Does
Because the flat face makes area contact rather than a point bite, DIN 551 holds by friction and clamp force. That makes it repeatable — you can back it off and re-seat it many times without chewing up the shaft — which is why it is favoured for calibration stops, adjustable pointers, and clamping against a pre-ground surface. When you instead need the screw to lock permanently, a cone point (DIN 553) or cup point bites in and resists rotation far better.
Why Brass
In CW614N brass, DIN 551 is chosen for non-marring adjustment, corrosion resistance and electrical work — clamping wires and flat conductors in terminals, holding light collars in instruments, and marine or decorative assemblies. Brass will not seize in aluminium or brass housings the way plated steel can. For heavy clamp loads on steel shafts we can quote the same part in steel or stainless.
DIN 551 Dimensions (mm)
| Thread d | Pitch P | Flat point dia. dp (max) | Slot width n | Slot depth t (min–max) | Length l range |
|---|---|---|---|---|---|
| M1.6 | 0.35 | 0.8 | 0.25 | 0.56–0.74 | 2–8 |
| M2 | 0.4 | 1.0 | 0.25 | 0.64–0.84 | 2–10 |
| M2.5 | 0.45 | 1.5 | 0.4 | 0.72–0.95 | 2.5–12 |
| M3 | 0.5 | 2.0 | 0.4 | 0.8–1.05 | 3–16 |
| M4 | 0.7 | 2.5 | 0.6 | 1.12–1.42 | 4–20 |
| M5 | 0.8 | 3.5 | 0.8 | 1.28–1.63 | 5–25 |
| M6 | 1.0 | 4.0 | 1.0 | 1.6–2.0 | 6–30 |
| M8 | 1.25 | 5.5 | 1.2 | 2.0–2.5 | 8–40 |
| M10 | 1.5 | 7.0 | 1.6 | 2.4–3.0 | 10–50 |
| M12 | 1.75 | 8.5 | 2.0 | 2.8–3.6 | 12–60 |
Standard nominal values; verify sizes stocked/tooled before ordering — other sizes to order.
DIN 551 corresponds to ISO 4766. Also cross-referenced as CSN 021184 and PN 82272. For the part-threaded flat-point variant, see DIN 427 slotted headless screws.
Materials — Brass Grades
| Grade | Standard | Character | Typical composition |
|---|---|---|---|
| CW614N | EN 12164 | Free-machining brass (standard) | ~58% Cu, ~3% Pb, bal. Zn |
| CW617N | EN 12165 | Hot-forging brass | ~58% Cu, ~2% Pb, bal. Zn |
| IS 319 | IS 319 | Free-cutting brass (Indian) | ~57–59% Cu, Pb, bal. Zn |
| MS / SS 303/304/316 | — | On request | Mild steel or stainless |
Also available in MS and SS 303/304/316 on request.
Finish Options
Natural brass as standard; on request nickel plating, tin plating, or bright dip / passivation. Steel and stainless variants can be supplied plain, zinc plated, or black oxide.
Manufacturing & Export Capability
Custom manufacturing from drawing/sample · MOQ: 500 pcs (typical) · Lead time 1–2 weeks · ISO 9001:2015 · Export packing · FOB Mundra / CIF worldwide · Brass specialist in Jamnagar, India’s brass city
18+ years of manufacturing experience · 19 skilled workers · Sales@definitemetal.com
Applications & Industries
DIN 551 brass flat-point set screws are used in electrical terminals and connectors, measuring and calibration instruments, light shaft collars and clamps, marine hardware, and general adjustment mechanisms where the mating surface must stay unmarked.
Frequently Asked Questions
Choose flat when the screw will be adjusted repeatedly, or when it bears on a hardened or finished surface you do not want to dent. Cup and cone points bite in and are better for locking that stays put.
It holds by friction and clamp force, which brass provides well for light and medium duty. For maximum holding torque on a hardened steel shaft, a steel or stainless screw is the stronger choice — we can quote either.
Standard threads M1.6 to M12 with the lengths shown in the dimension table, plus custom lengths to your drawing.
ISO 4766 covers the same slotted flat-point set screw.
Typically 500 pcs per size, with a lead time of 1 to 2 weeks.