S-90604A309 4-40 x 5/16" ASME B18.6.3 Stainless Steel Pan Head Combination Phillips/Slotted Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and passivated finish for extended service life in harsh environments
• Exceptional mechanical strength delivering 100,000 psi tensile strength and Rockwell B100 hardness for reliable load-bearing performance
• Precision thread engagement with Class 2A fit and UNC coarse threads ensuring secure fastening and vibration resistance
• Dual-drive versatility featuring both Phillips and slotted drive options for flexible installation with standard tools
• Optimized head design with rounded pan profile providing consistent surface contact and reduced risk of damage during tightening
• Full regulatory compliance meeting ASME B18.6.3 manufacturing standards and environmental regulations including RoHS 3 and REACH
• Complete thread coverage with fully threaded 5/16" length for maximum grip strength across the entire fastener

Professional Applications & Engineering Value

These 4-40 UNC rounded head screws deliver critical performance advantages for industrial assembly applications where corrosion resistance and mechanical reliability are paramount. The 18-8 stainless steel composition combined with passivated finish creates a protective barrier against chemical exposure and atmospheric corrosion, making them ideal for electronics enclosures, marine equipment, and food processing machinery. The Class 2A thread fit ensures consistent engagement with mating components while the coarse thread spacing provides rapid installation and superior resistance to vibration loosening. The dual Phillips/slotted drive configuration offers installation flexibility for both automated assembly lines and field maintenance scenarios, while the rounded pan head design distributes clamping force evenly without marring sensitive surfaces.

Specification Summary & Compliance

Manufactured to exacting dimensional standards with Class 2A thread fit tolerance and UNC thread form specifications. These fully threaded screws feature a 4-40 thread size with coarse spacing and right-hand direction. Compliance includes ASME B18.6.3 mechanical standards for dimensional consistency, along with full adherence to RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations for hazardous substance restrictions.