Holo-krome 640000010 Button Socket Cap Screw 4-40

Product Description

The HOLO-KROME 640000010 is a button socket cap screw designed for fastening applications that require a low-profile head and a secure hex socket drive. Sized at 4-40 thread and 3/16 inches length under head, this screw is fully threaded and manufactured from alloy steel with a black oxide finish. The button head profile reduces protrusion in tight clearance assemblies. It conforms to ANSI/ASME B18.3 and ASTM F835 standards, with a thread fit class of 3A and hardness rated at 38 HRC. Installed with a 1/16-inch hex key, it is suited for precision mechanical assemblies, light machinery, and instrumentation work.

This screw fits applications where a UNC 4-40 thread pattern is specified and a flush or low-profile fastener is needed. Common use cases include panel assemblies, bracket mounting, electronic enclosures, and small mechanical components in industrial and commercial settings. The right-hand UNRC thread form is compatible with standard 4-40 tapped holes. Trades and technicians working in HVAC controls, electrical panel fabrication, and light mechanical assembly will find this size commonly specified on equipment drawings and service documentation.

Key Features

• Button head profile provides a low-profile, rounded appearance suitable for clearance-sensitive assemblies
• Hex socket drive (1/16 inches) allows torque application in confined spaces
• Alloy steel construction with 38 HRC hardness provides strength for mechanical fastening
• Black oxide finish offers mild corrosion resistance and reduces light reflection
• Fully threaded 4-40 UNC shank for full thread engagement in shallow tapped holes
• Conforms to ANSI/ASME B18.3 and ASTM F835 fastener standards

Compatibility

Designed as a direct-fit replacement or standard-use fastener for any application specifying a 4-40 UNC, 3/16-inch length under head, button socket cap screw per ANSI/ASME B18.3.

Installation Notes

Installation requires a 1/16-inch hex key or hex socket driver. Verify the receiving tapped hole meets 4-40 UNC thread specifications before installation. Do not over-torque small-diameter fasteners, as alloy steel button head screws at this size can be susceptible to head shear under excessive loading. Wear appropriate eye protection when working with small fasteners in pressurized or spring-loaded assemblies.