S-91500A120 4-40 x 3/16" ASME B18.6.3 Stainless Steel Phillips Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 316 Stainless Steel construction and passivated finish, ideal for harsh industrial environments
• Exceptional mechanical strength delivering 70,000 psi tensile strength and Rockwell B80 hardness for reliable, long-term performance
• Precise flush mounting with undercut flat head and 82° countersink angle for seamless, vibration-resistant installations
• Easy installation and removal using standard Phillips #1 drive, reducing assembly time and tool wear
• Consistent thread engagement with UNC coarse threading and Class 2A fit, ensuring secure fastening in various materials
• Full thread coverage along the 3/16" length for maximum grip and load distribution
• Compliance with industry standards including ASME B18.6.3, RoHS 3, and REACH for quality assurance and environmental safety

Professional Applications & Engineering Value

These 4-40 UNC flat head screws are engineered to address critical challenges in demanding applications where corrosion resistance, mechanical integrity, and precise installation are paramount. The 316 Stainless Steel material, combined with a passivated finish, provides excellent protection against chemicals, moisture, and salt spray, making these Phillips drive screws ideal for marine, chemical processing, and outdoor equipment. The undercut flat head design ensures a flush fit that minimizes protrusion and reduces the risk of snagging or interference in compact assemblies. With a coarse thread and Class 2A thread fit, these screws offer reliable performance in soft metals, plastics, and wood, preventing stripping and ensuring vibration resistance. Fully threaded for uniform stress distribution, they are widely used in electronics enclosures, machinery panels, and structural components requiring ASME B18.6.3 compliance and high tensile strength.

Specification Summary & Compliance

This product adheres to Class 2A thread fit tolerances per UNC standards, ensuring precise dimensional accuracy and interchangeability. Manufacturing and material specifications comply with ASME B18.6.3 for consistent quality and performance. Environmental and safety regulations are met, including RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant status, confirming the absence of restricted substances. The screws feature a fully threaded 3/16" length, 82° countersink angle, and are designed for right-hand threading applications.