S-91221A218 4-40 x 5/8" UL 94 HB Plastic Socket Head Screws

Key Features & Benefits at a Glance

• Lightweight yet durable construction using glass-filled nylon material for excellent strength-to-weight ratio in demanding applications
• Corrosion-resistant plastic composition eliminates rust concerns and maintains performance in humid or chemical environments
• Precise Class 2A thread fit ensures reliable engagement and consistent clamping force in assembly operations
• Wide temperature tolerance from -20° to 230°F maintains structural integrity across various operating conditions
• Standard hex drive design with 3/32" drive size provides secure tool engagement and prevents stripping during installation
• Full threading along 5/8" length offers maximum adjustability and uniform load distribution
• Comprehensive regulatory compliance including UL 94 HB, RoHS 3, and REACH ensures safety and environmental responsibility

Professional Applications & Engineering Value

This glass-filled nylon socket head cap screw delivers exceptional engineering value where metal fasteners would compromise performance. The 4-40 UNC coarse thread configuration provides rapid installation and reliable holding power in plastic and soft material assemblies. The off-white color and non-conductive properties make it ideal for electrical enclosures, while its high-temperature resistance up to 230°F suits automotive and industrial equipment applications. The hex drive system ensures positive torque transmission without cam-out, and the material's inherent lubricity prevents galling in repetitive assembly operations. These plastic fasteners solve critical challenges in industries requiring non-magnetic, non-corrosive components that meet stringent UL 94 HB flammability standards.

Specification Summary & Compliance

This socket head cap screw features precise Class 2A thread fit according to UNC standards, ensuring consistent engagement and reliable performance. The fully threaded 5/8" length provides complete fastening capability with standard 3/32" hex drive compatibility. Manufacturing complies with UL 94 HB flammability requirements for material safety, while meeting RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations for hazardous substance restriction and chemical safety compliance in industrial applications.