Holo-krome 86646 Hex Socket Cap Screw 5/16-18 Unc 4 in

Product Description

The HOLO-KROME 86646 is a hex socket cap screw designed for secure, high-strength fastening in mechanical assemblies, tooling fixtures, and industrial equipment. It features a 5/16-18 UNC thread size with a 4-inch length under the head and is partially threaded for proper clamping engagement. The 1/4-inch hex drive accepts a standard hex key or Allen wrench. Constructed from alloy steel with a black oxide finish, this fastener delivers solid tensile strength and moderate corrosion resistance in dry or lightly oiled service environments. It meets ASME B18.3 and ASTM A574 standards.

This screw is suited for use in machine tool setups, jigs, dies, and general industrial fabrication where a recessed drive fastener is required. The partial threading is appropriate for through-hole and clearance-hole applications that require clamping force between mating surfaces. It is commonly installed by machinists, millwrights, maintenance technicians, and mechanical contractors working on equipment assembly or structural fixturing.

Key Features

• 5/16-18 UNC thread form for compatibility with standard inch-series tapped holes
• 4-inch length under head with partial threading for proper clamping grip
• 1/4-inch hex socket drive for use with Allen keys or hex bit drivers
• Alloy steel construction provides high tensile and shear strength
• Black oxide finish offers mild corrosion resistance and low-glare appearance
• Meets ASME B18.3 and ASTM A574 dimensional and mechanical standards

Compatibility

Designed as a standard inch-series hex socket cap screw for use in any 5/16-18 UNC tapped hole requiring a 4-inch partially threaded fastener per ASME B18.3 specifications.

Installation Notes

Installation is performed with a 1/4-inch hex key or Allen-style bit driver. Ensure the mating tapped hole is clean and free of debris before driving. De-energize and lock out any equipment before fastener removal or replacement on live machinery. Torque to the value specified by the equipment manufacturer for 5/16-18 alloy steel fasteners in the applicable joint design.