S-90008A421 4-40 x 1/4" ASME B18.3, ASTM F837 18-8 Stainless Steel Socket Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with silver-plated 18-8 stainless steel construction, ideal for harsh environments and extended service life.
• High tensile strength of 70,000 psi ensures reliable load-bearing capacity and prevents failure under stress in critical assemblies.
• Precision Class 3A thread fit guarantees tight, secure fastening with minimal backlash for vibration-resistant connections.
• Rockwell B70 hardness provides excellent wear resistance and maintains thread integrity during repeated installations.
• 3/32" hex socket drive allows for high-torque application with standard tools, reducing slippage and tool wear.
• Fully threaded design offers consistent clamping force along the entire length for uniform pressure distribution.
• Compliance with ASME B18.3 and ASTM F837 ensures adherence to industry standards for dimensional accuracy and performance reliability.

Professional Applications & Engineering Value

Engineered for demanding industrial settings, these 4-40 UNC thread socket head cap screws combine silver-plated 18-8 stainless steel with a coarse thread profile to deliver exceptional corrosion resistance and ease of assembly in high-vibration applications. The Class 3A fit and fully threaded rod ensure precise engagement and uniform stress distribution, reducing the risk of loosening in machinery, aerospace components, and electronic enclosures. With a 70,000 psi tensile strength and Rockwell B70 hardness, they address common failure points like galling and fatigue, providing long-term reliability in industrial fasteners where durability and compliance with strict standards are paramount.

Specification Summary & Compliance

This socket head cap screw features a 4-40 UNC coarse thread with Class 3A fit for precise dimensional tolerance, a length of 1/4", and a right-hand thread direction. It conforms to ASME B18.3 and ASTM F837 specifications, ensuring consistent manufacturing quality. Additionally, it is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting environmental and safety regulations for global industrial use.