Holo-krome 77556 Hex Socket Cap Screw 1/2-20 Unf 6 in

Product Description

The HOLO-KROME 77556 is a partially threaded hex socket cap screw designed for high-strength fastening applications. It features a 1/2-20 UNF thread size and a 6-inch length under head, making it suitable for deep-grip or longer-reach bolting needs. Driven by a 3/8-inch hex key, the screw is manufactured from alloy steel and finished with a black oxide coating that provides moderate corrosion resistance and reduces light reflection. This fastener meets ASME B18.3 and ASTM A574 standards, confirming its dimensional and mechanical compliance. It is installed by machinists, maintenance technicians, and mechanical contractors in structural and equipment assembly work.

This socket cap screw is used in applications requiring a recessed, low-profile drive head with high clamping force. The partial thread design concentrates clamping load along the shank, making it well suited for through-bolt and thick-flange assemblies. Typical install scenarios include machinery frames, fixture plates, tooling jigs, and industrial equipment where a flush or countersunk head profile is required. The black oxide finish is appropriate for indoor and lightly controlled environments where full corrosion protection from plating is not required.

Key Features

• 1/2-20 UNF thread for fine-pitch engagement and precise clamping
• 6-inch length under head accommodates thick material stacks and deep assemblies
• Partial threading keeps clamping load on the shank rather than the threads
• 3/8-inch hex socket drive for torque application with standard Allen keys or hex bits
• Alloy steel construction meets ASTM A574 mechanical requirements
• Black oxide finish provides mild corrosion resistance and low-glare appearance

Compatibility

Designed as a standard ASME B18.3 hex socket cap screw in 1/2-20 UNF thread, compatible with any tapped hole or nut meeting UNF Class 2B or 3B specifications at the corresponding thread size.

Installation Notes

Installation should be performed by a qualified machinist or mechanical technician using a correctly sized 3/8-inch hex key or socket bit to avoid cam-out and fastener damage. De-energize and lock out all equipment before servicing any fastened assembly. Apply thread lubricant or fastener-grade anti-seize as appropriate for the application and base material to achieve accurate torque-to-clamp-load results. Follow applicable equipment manufacturer torque specifications and relevant ASME or ASTM guidelines for the fastener grade.