Holo-krome 60078 Flat Socket Cap Screw 5/16-18 X 3/4 in

Product Description

The HOLO-KROME 60078 is a flat socket cap screw designed for applications requiring a flush or countersunk fastener profile. It features an 82-degree flat head with a 3/16-inch hex socket drive, accepting a standard hex key for installation and removal. The screw is manufactured from alloy steel with a black oxide finish, providing moderate corrosion resistance and a low-reflectance appearance. It carries a Thread Fit Class 3A designation and a hardness rating of 39-44 HRC, making it suitable for high-stress mechanical assemblies. Fully threaded along its 3/4-inch overall length, this 5/16-18 UNC fastener is installed by machinists, maintenance technicians, and mechanical assemblers across industrial and OEM applications.

This flat socket cap screw is used in machine frames, jigs, fixtures, tooling plates, and general mechanical assemblies where the fastener head must sit flush with or below the mating surface. The countersunk profile suits applications where protrusion would interfere with moving parts, mating components, or safety guarding. It meets ASME B18.3 and ASTM F835 standards, making it appropriate for commercial and industrial mechanical work. Minimum order quantity is 100 pieces per the manufacturer requirement.

Key Features

• 82-degree flat head with 3/16-inch hex socket drive for flush countersunk installation
• Alloy steel construction with 39-44 HRC hardness for high-strength fastening
• Black oxide finish for low reflectance and moderate corrosion resistance
• Fully threaded 5/16-18 UNC, Thread Fit Class 3A for precise thread engagement
• Meets ASME B18.3 and ASTM F835 fastener standards
• Overall length measured as full length per ASME convention

Compatibility

Designed as an OEM-style and maintenance replacement flat socket cap screw for machinery, fixtures, and assemblies requiring a 5/16-18 UNC fully threaded countersunk fastener conforming to ASME B18.3 and ASTM F835 standards.

Installation Notes

Installation requires a 3/16-inch hex key or hex socket bit. Countersink the mating material to 82 degrees prior to installation to achieve a proper flush fit. Torque to values consistent with Grade 8 or equivalent alloy steel fastener specifications for the thread size, referencing applicable engineering or maintenance documentation. Power down and de-energize any associated equipment before fastener service in mechanical assemblies.