S-91773A106 4-40 x 1/4" ASME B18.6.3 Stainless Steel Round Head Phillips Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel and passivated finish for extended service life in harsh environments
• High-strength performance with 100,000 psi tensile strength and Rockwell B100 hardness for reliable load-bearing applications
• Optimized installation efficiency through Phillips No. 1 drive and rounded head design for quick, secure fastening
• Precision thread engagement with Class 2A UNC coarse threads ensuring consistent fit and vibration resistance
• Full-threaded design providing maximum grip length and uniform stress distribution across the entire fastener
• Regulatory compliance meeting ASME B18.6.3 standards for dimensional accuracy and quality assurance
• Environmental responsibility with RoHS 3 and REACH compliance for safe use in regulated industries

Professional Applications & Engineering Value

These 4-40 UNC rounded head Phillips screws deliver exceptional engineering value in industrial fastening applications where corrosion resistance and mechanical strength are critical. The 18-8 stainless steel construction combined with passivated finish provides superior protection against chemical exposure and atmospheric corrosion, making them ideal for electronics enclosures, machinery assemblies, and marine equipment. The coarse UNC thread design ensures rapid installation and reliable performance in materials where fine threads might strip or fail. With full threading along the entire 1/4" length, these screws distribute clamping force evenly, reducing stress concentration points that can lead to joint failure. The rounded head profile and Phillips drive system offer both aesthetic appeal and practical installation benefits, preventing snagging while accommodating standard driving tools for efficient assembly line operations.

Specification Summary & Compliance

This 4-40 UNC screw features precise Class 2A thread fit tolerances according to ASME B18.6.3 specifications, ensuring consistent dimensional accuracy and reliable performance. The manufacturing process adheres to strict quality standards with fully threaded design, 1/4" length, and 0.112" thread diameter. Regulatory compliance includes full conformance with RoHS 3 (2015/863/EU) restrictions on hazardous substances and REACH (EC 1907/2006) regulations for chemical safety, making these screws suitable for use in environmentally sensitive applications and regulated industries worldwide.