Socket Screw

Socket cap screws, also known as hex socket head cap screws, are high-strength threaded fasteners featuring a cylindrical head with a recessed hexagonal drive (Allen key drive). This internal drive design allows for high torque application without slipping or cam-out, making them ideal for precision machinery, tooling, and applications requiring flush or countersunk installation. Available in both inch and metric series, with multiple head styles to suit different clearance and aesthetic requirements.

Available Head Styles

Head Type	Description	Typical Applications
Socket Cap Screw	Standard cylindrical head with high height-to-diameter ratio; provides deep socket for maximum torque transfer	General industrial machinery, tooling, precision assemblies
Flat Socket Cap Screw (Countersunk)	90° countersunk head for flush mounting; provides a smooth, low-profile surface	Applications requiring a flush finish with no protruding head
Button Socket Cap Screw	Low-profile, rounded head with wider bearing surface; aesthetically pleasing	Thin sheet metal, decorative applications, where head clearance is limited
Low Head Socket Cap Screw	Reduced head height compared to standard socket cap screw; provides higher strength than button head while maintaining low profile	Applications with minimal head clearance that still require high strength
Low Head with Collar (Pilot)	Low head with integral guide collar; provides self-centering and additional bearing surface	Precision assemblies requiring alignment assistance

Applicable Standards

Head Style	Standard (Metric)	Notes
Socket Cap Screw	DIN 912 / ISO 4762	DIN 912 replaced by ISO 4762; dimensions interchangeable for M3–M24
Flat Socket Cap Screw	DIN 7991 / ISO 10642	DIN 7991 replaced by ISO 10642; note: some sizes (M18, M22, M24) removed in ISO version
Button Socket Cap Screw	ISO 7380-1 / ISO 7380-2	ISO 7380-1: standard button head; ISO 7380-2: flanged button head
Low Head Socket Cap Screw	DIN 7984 / ISO 7380-2	DIN 7984 widely used; ISO 7380-2 may partially replace but dimensions differ
Low Head with Collar	DIN 6912	No direct ISO equivalent; standard remains valid

Inch Series

Standard	Description
ASME B18.3	Socket cap, shoulder, and set screws – inch series

Additional Drive Options

Pin-In-Hex (Tamper-Resistant): Hex socket with center pin for security applications
Torx (Star Drive): Enhanced torque transfer with reduced cam-out

Mechanical Properties

Property Class (Metric)	Grade (Inch)	Tensile Strength	Hardness
4.8	—	400 MPa min	—
8.8	—	800 MPa min	—
10.9	—	1,000 MPa min	—
12.9	—	1,200 MPa min	—
—	Grade 8	150,000 psi min	Rockwell C33–39
—	Alloy Steel	180,000 psi min (typical)	—

Materials

Alloy Steel – Heat-treated for high strength; standard for property classes 10.9 and 12.9
Stainless Steel – Grades 304 (A2), 316 (A4) for corrosion resistance
Brass – Decorative, non-magnetic, corrosion resistant
Aluminum – Lightweight, non-magnetic
Other Special Materials – Available upon request

Surface Finishes