S-91087A135 1/4"-20 x 3 1/2" Wood Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-phosphate steel coating for extended service life in demanding environments
• Enhanced torque transmission through T30 Torx drive system, reducing cam-out and tool slippage during installation
• Optimized material displacement with thread forming design creates stronger, vibration-resistant connections in wood and sheet metal
• Clean flush installation achieved through standard flat head profile with 82° countersink angle for professional finish
• Reduced assembly time with No. 3 drill bit compatibility and coarse UNC threading for faster driving
• Controlled thread engagement through partially threaded design prevents material splitting while maintaining maximum holding power
• Regulatory compliance assurance meeting RoHS 3 and REACH standards for international project requirements

Professional Applications & Engineering Value

These 1/4"-20 thread forming screws are engineered to solve common fastening challenges in wood and sheet metal applications. The black-phosphate steel construction provides exceptional corrosion protection, while the Torx T30 drive system delivers superior torque transfer, eliminating stripped drive heads during high-torque installations. The thread forming design creates permanent, vibration-resistant connections by displacing material rather than removing it, resulting in up to 30% higher pull-out strength compared to conventional threading. The partially threaded shank and 82° countersink angle work together to prevent material splitting in delicate wood applications while ensuring flush mounting in sheet metal assemblies. These features make these UNC coarse thread screws ideal for heavy-duty construction, furniture manufacturing, and metal framing applications where reliability and durability are critical.

Specification Summary & Compliance

Manufactured to precise dimensional standards with UNC coarse threading (1/4"-20) and Class 2A thread tolerances for consistent performance. The 3 1/2" length with 1 1/2" minimum thread length ensures proper engagement depth. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, making them suitable for global industrial applications. Designed for use with No. 3 drill bits (0.213" diameter) and featuring right-hand threading with standard flat head profile for universal compatibility.