Value Collection 201019PR Button Socket Cap Screw 4-40

Product Description

The VALUE COLLECTION 201019PR is a fully threaded button socket cap screw intended for precision fastening applications in mechanical assemblies and fabricated components. It features a 4-40 UNC thread and a 1/2-inch length under head, with a low-profile button head designed to sit flush or nearly flush in countersunk or clearance applications. The screw is machined from alloy steel and finished with a black oxide coating that provides a degree of corrosion resistance and reduces light reflection. Drive engagement is via a 1/16-inch hex socket. Hardness is rated at 36 to 43 HRC, meeting ANSI/ASME B18.3 and ASTM F835 standards. This fastener is handled and installed by machinists, maintenance technicians, and assembly professionals.

This screw is suited for light-duty to medium-duty mechanical assemblies where a low-profile head is required and clearance above the fastener is limited. Common applications include instrument panels, electronics enclosures, fixture plates, jigs, and precision mechanical subassemblies. The black oxide finish makes it a standard choice where bare metal fasteners are not acceptable for aesthetic or mild corrosion-resistance reasons. The fine 4-40 thread pitch provides strong thread engagement in thin materials and tapped holes in aluminum, steel, and similar substrates.

Key Features

• Fully threaded 4-40 UNC right-hand thread with Class 3A thread fit for precise engagement
• Low-profile button head design reduces protrusion above mating surface
• 1/16-inch hex socket drive for use with standard hex keys or Allen drivers
• Alloy steel construction rated 36 to 43 HRC for reliable mechanical strength
• Black oxide coating provides mild corrosion resistance and low-reflectance finish
• Conforms to ANSI/ASME B18.3 and ASTM F835 fastener standards

Compatibility

Designed as a standard replacement or production fastener for applications requiring a 4-40 UNC fully threaded button socket cap screw per ANSI/ASME B18.3 and ASTM F835 specifications.

Installation Notes

Install using a 1/16-inch hex key or Allen driver; do not substitute a driver of incorrect size as it will damage the socket recess. Verify that the tapped hole thread class is compatible with the 3A thread fit before installation. Torque to the value specified by the assembly engineer or applicable fastener standard for 4-40 alloy steel fasteners. Avoid over-torquing the button head style, as the reduced head height limits the bearing surface compared to a standard socket cap screw.