Alloy Metric Socket Set Screws

Metric Alloy Socket Set Screws — DIN 913–916, Class 45H, Multiple Point Styles

Shop Metric Alloy Socket Set Screws

Metric socket set screws follow the DIN 913–916 standard series, with each DIN number specifying a different point style. Class 45H alloy steel provides through-hardening equivalent to the ASME B18.3 RC 45–53 specification used for inch-series alloy set screws — the metric designation reflects a Vickers hardness range rather than Rockwell C, but the materials and hardness levels are directly comparable. Metric set screws are used in European and Asian-designed equipment, metric-thread shaft assemblies, and import machinery serviced with metric tooling.

DIN Standard Reference for Point Styles

DIN 916 — Cup Point is the most widely used metric set screw standard. The hardened cup tip bites into the shaft surface for strong resistance to rotation and axial movement — the correct default for most metric shaft assemblies.

DIN 913 — Flat Point applies force over a flat contact area, minimizing shaft marring. Use on hardened shafts, precision ground components, or applications requiring frequent adjustment without cumulative shaft damage.

DIN 914 — Cone Point is designed to seat permanently in a matching drilled dimple, providing the highest holding power of any point style. For permanent or semi-permanent locking only — not for adjustment applications.

DIN 915 — Dog Point features an extended cylindrical pilot that keys positively into a matching hole or slot, providing repeatable mechanical engagement for applications requiring precise, repeated repositioning.

Hex Key Sizes for Metric Set Screws

Metric set screws use the same hex key size as their inch-series equivalents relative to thread diameter. Common metric pairings: M3 uses 1.5mm; M4 uses 2mm; M5 uses 2.5mm; M6 uses 3mm; M8 uses 4mm; M10 uses 5mm; M12 uses 6mm; M16 uses 8mm. These are smaller than the hex keys used for metric socket head cap screws of the same thread size.

Frequently Asked Questions

What DIN standard covers metric cup point socket set screws?
DIN 916 covers metric socket set screws with cup point. The related standards are: DIN 913 (flat point), DIN 914 (cone point), and DIN 915 (dog point). All four are headless hex socket set screws differing only in point style. Class 45H is the standard alloy property class for all four.

What is Class 45H for metric set screws?
Class 45H designates the hardness requirement for metric alloy socket set screws — a Vickers hardness of 45 HRC minimum (equivalent to Rockwell C 45). This through-hardened condition allows the cup point to bite into and grip standard steel shafts. The equivalent ASME designation for inch-series set screws is RC 45–53.

Can metric alloy set screws be used on hardened shafts?
No. Class 45H alloy set screws are not hard enough to penetrate hardened shaft surfaces. Use DIN 913 flat point metric set screws against hardened shafts to distribute load over a flat contact area without requiring shaft penetration.

What hex key size do metric socket set screws use?
Common pairings: M3 uses 1.5mm, M4 uses 2mm, M5 uses 2.5mm, M6 uses 3mm, M8 uses 4mm, M10 uses 5mm, M12 uses 6mm. These are smaller keys than used for metric SHCS of the same thread size.

Metric alloy socket set screws are used alongside metric socket head cap screws and metric shoulder bolts in the same assemblies — set screws for shaft locking, cap screws for clamping, shoulder bolts for pivot and guide applications. For corrosive environments requiring metric set screws, see metric stainless socket set screws. For inch-series shaft assemblies, see alloy steel socket set screws (ASME B18.3). The full set screw selection and all socket fastener types are available through the Socket Set Screws and Sockets categories.