S-91259A155 4-40 ASTM A574 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 140,000 psi ensures reliable performance in high-stress industrial applications, reducing the risk of fastener failure.
• Superior corrosion resistance from the black oxide finish prolongs service life in harsh environments, minimizing maintenance needs.
• Precise Class 3A thread fit guarantees secure, vibration-resistant assemblies with consistent engagement and reduced loosening.
• High shear strength of 84,000 psi provides robust load-bearing capacity for dynamic or heavy-duty mechanical systems.
• Rockwell C32 hardness offers excellent wear resistance, maintaining dimensional stability under repeated use.
• Socket head with hex drive allows for easy installation and removal in confined spaces, improving assembly efficiency.
• Compliance with ASTM A574 ensures material quality and manufacturing consistency for dependable engineering applications.

Professional Applications & Engineering Value

This alloy steel shoulder screw with a 4-40 UNC coarse thread and black oxide finish is engineered to address common industrial challenges such as component misalignment, vibration-induced loosening, and corrosion. The shoulder design provides precise positioning for rotating parts in machinery, jigs, and assemblies, while the Class 3A thread fit ensures tight tolerances for secure fastening in high-vibration environments like automotive, aerospace, and manufacturing equipment. Its high tensile and shear strength makes it ideal for load-bearing applications, reducing downtime and enhancing operational reliability. The corrosion-resistant finish further extends service life in humid or chemically exposed settings, offering long-term cost savings and performance consistency.

Specification Summary & Compliance

This shoulder screw features a 4-40 UNC coarse thread with Class 3A fit for precise threading and secure assembly. It adheres to ASTM A574 specifications for material and manufacturing quality, ensuring consistent performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, meeting environmental and safety standards for industrial use. Dimensions include a shoulder diameter of 1/8" with tight tolerances and a thread length of 5/32", providing accuracy for engineering applications.