S-91858A841 4-40 x 3/16" ASME B18.6.3 Stainless Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 316 stainless steel construction and passivated finish, ideal for harsh environments and extended service life.
• High-strength performance offering 70,000 psi tensile strength and Rockwell B80 hardness for reliable load-bearing in demanding applications.
• Precision thread fit with Class 2A UNC coarse threads ensuring easy installation and secure, vibration-resistant connections.
• Optimized head design featuring an undercut flat head with an 82° countersink for a flush, clean finish that minimizes protrusion.
• Broad compatibility due to compliance with ASME B18.6.3 standards, guaranteeing dimensional accuracy and interchangeability.
• Environmental responsibility with RoHS 3 and REACH compliance, meeting strict regulatory requirements for industrial use.
• Full-threaded design providing maximum grip and holding power along the entire screw length for superior fastening integrity.

Professional Applications & Engineering Value

Engineered for precision and durability, these 4-40 UNC flat head machine screws are crafted from 316 stainless steel with a passivated finish to combat corrosion in challenging settings like marine, chemical processing, and outdoor equipment. The fully threaded design and Class 2A fit ensure tight, reliable fastening that resists loosening under vibration, while the undercut flat head with an 82° countersink allows for a seamless surface finish, reducing snagging and improving aesthetics. Ideal for assembly lines, machinery, and electronic enclosures, these screws address common industrial pain points—such as material degradation and fastener failure—by delivering consistent tensile strength and compliance with ASME B18.6.3, making them a trusted choice for engineers prioritizing longevity and regulatory adherence.

Specification Summary & Compliance

This screw adheres to precise dimensional standards, including a Class 2A thread fit and UNC coarse threading for reliable engagement. It meets ASME B18.6.3 specifications for flat head machine screws, ensuring uniformity and performance. Additionally, the product is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, supporting environmental safety in industrial applications.