Holo-krome 640010280 Button Socket Cap Screw 5-40

Product Description

The HOLO-KROME 640010280 is a 5-40 button socket cap screw designed for applications requiring a low-profile fastener with high tensile strength. The button head style provides a wide bearing surface and a rounded top profile, making it suited for assemblies where clearance above the joint surface is limited. Drive engagement is via a 5/64-inch hex socket. The screw is fully threaded, manufactured from alloy steel, and finished in black oxide for mild corrosion resistance and reduced reflectivity. Thread fit is Class 3A, indicating a standard close tolerance for general mechanical assembly. Hardness is rated at 38 HRC.

This fastener is used in light mechanical assemblies, precision equipment, and machine components where a clean, flush-profile head is needed. The 1/4-inch length under head and 5-40 UNC thread make it appropriate for thin-section or sheet metal applications. It is commonly installed by machinists, mechanical assemblers, and equipment technicians working with small-format fasteners in tight-clearance environments.

Key Features

• Button head profile provides low clearance height of 0.066 inches above the mating surface
• 5/64-inch hex socket drive for precise torque application in confined spaces
• Alloy steel construction rated at 38 HRC hardness
• Black oxide finish for mild corrosion resistance and low-reflectivity surface
• Class 3A thread fit per ANSI/ASME B18.3 and ASTM F835
• Fully threaded shank along the 0.25-inch length under head

Compatibility

Designed as an OEM-style replacement or direct-use fastener for mechanical assemblies requiring a 5-40 UNC fully threaded button socket cap screw per ANSI/ASME B18.3 and ASTM F835 standards.

Installation Notes

Installation requires a 5/64-inch hex key or hex socket bit. Power down or de-energize any equipment before accessing fastener locations in live assemblies. Follow applicable torque guidelines for 5-40 alloy steel fasteners per the relevant ASME standard. Avoid overtightening, as the small thread diameter is susceptible to thread stripping under excessive load.