S-90403A842 1/4"-28 x 1" ASME B18.13 Steel Pan Head Phillips Screws with Internal-Tooth Lock Washer

Key Features & Benefits at a Glance

• Vibration-resistant locking with integrated internal-tooth lock washer prevents loosening in high-stress applications
• Superior corrosion protection through zinc-plated steel construction for extended service life in harsh environments
• High tensile strength rating of 60,000 psi ensures reliable performance under heavy mechanical loads
• Precision Class 2A thread fit provides consistent engagement and reduces cross-threading risks during assembly
• Phillips drive compatibility with No. 3 size offers familiar, efficient installation using standard tools
• Full threading design delivers maximum grip length and uniform stress distribution
• Industry standard compliance with ASME B18.13 ensures interchangeability and quality consistency

Professional Applications & Engineering Value

These zinc-plated steel screws with internal-tooth lock washers solve critical vibration-induced loosening problems in industrial equipment, automotive assemblies, and machinery frames. The 1/4"-28 UNF fine threading combined with Class 2A thread fit creates precise, reliable fastening in applications requiring repeated disassembly. The rounded pan head profile with Phillips drive facilitates quick installation while the integrated locking mechanism eliminates the need for separate washers, reducing assembly time and part inventory. Engineered for 60,000 psi tensile strength and Rockwell B69 hardness, these fasteners maintain integrity in high-vibration environments where standard screws typically fail.

Specification Summary & Compliance

Manufactured to ASME B18.13 standards with Class 2A thread fit and UNF fine thread spacing. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. Features precise dimensional control with 1" length, 0.25" thread diameter, and 0.492" head diameter for consistent performance across industrial applications.