S-90275A106 4-40 x 1/4" ASME B18.6.3 Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with zinc-plated steel construction, extending service life in demanding industrial environments
• Precise countersinking capability with 82° flat head profile for flush mounting and clean aesthetic finishes
• Reliable thread engagement through Class 2A thread fit and UNC coarse threading, ensuring vibration-resistant connections
• Enhanced durability with Rockwell B70 hardness, maintaining structural integrity under mechanical stress
• Full-threaded design providing maximum grip length and uniform load distribution across the entire fastener
• Standard-compliant performance meeting ASME B18.6.3 specifications for dimensional accuracy and mechanical properties
• Environmental compliance with RoHS 3 and REACH regulations, ensuring safe use in regulated industries

Professional Applications & Engineering Value

These 4-40 UNC zinc-plated steel flat head screws deliver exceptional engineering value in applications where space constraints and corrosion resistance are critical. The slotted drive style provides traditional installation compatibility while the fully threaded design ensures maximum holding power in thin materials and tight assemblies. The 82° countersink angle allows for seamless flush mounting in precision machinery, electronic enclosures, and automotive components, eliminating protrusions that could interfere with moving parts. The zinc-plated steel construction creates a protective barrier against moisture and chemical exposure, making these flat head screws ideal for industrial equipment, manufacturing fixtures, and outdoor applications where environmental factors would compromise ordinary fasteners. The combination of Rockwell B70 hardness and coarse threading ensures these screws maintain their mechanical properties even in high-vibration environments common in production facilities.

Specification Summary & Compliance

This 4-40 UNC flat head screw features precise Class 2A thread fit tolerances and coarse thread spacing per unified thread standards. Manufacturing strictly adheres to ASME B18.6.3 specifications for dimensional accuracy, mechanical properties, and performance requirements. The product is fully compliant with RoHS 3 (2015/863/EU) restrictions on hazardous substances and meets REACH (EC 1907/2006) regulations for chemical safety, ensuring environmental responsibility and regulatory acceptance across global markets.