S-91253A306 1/4"-28 x 5/16" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide coating, extending service life in demanding industrial environments
• Exceptional tensile strength (130,000 psi) prevents stripping and failure under high-load applications
• Precision Class 3A thread fit ensures secure, vibration-resistant fastening with minimal play
• 82° countersink angle design provides flush mounting for cleaner aesthetics and reduced snag hazards
• Hex drive compatibility (5/32") enables high-torque installation with standard industrial tools
• Fine thread spacing (UNF) delivers enhanced clamping force distribution for critical assemblies
• Full threading along 5/16" length maximizes engagement depth in limited-space applications

Professional Applications & Engineering Value

Engineered for precision assemblies requiring flush surface mounting, these black-oxide alloy steel flat head screws solve critical challenges in machinery, automotive, and aerospace applications. The 82° countersink angle seamlessly integrates with standard chamfered holes, eliminating protrusions that interfere with moving components. With Class 3A UNF fine threads, the fastener maintains clamping force under vibration while the Rockwell C39 hardness resists wear during repeated disassembly cycles. The hex drive system accommodates high installation torque without cam-out, making these fully threaded screws ideal for securing engine components, control panels, and precision instrumentation where reliability is non-negotiable.

Specification Summary & Compliance

Manufactured to ASTM F835 specifications with Class 3A thread fit tolerances and UNF 1/4"-28 fine threading. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. Features right-hand thread direction with 0.25" thread diameter and 5/16" length for standardized industrial applications.