S-90324A016 4-40 Shoulder Screws

Key Features & Benefits at a Glance

• Exceptional Corrosion Resistance: Crafted from 18-8 stainless steel, this screw offers superior durability in harsh environments, reducing maintenance costs and extending service life.
• High Tensile & Shear Strength: With a tensile strength of 70,000 psi and minimum shear strength of 35,000 psi, it ensures reliable performance under heavy loads and vibration.
• Precision Class 3A Thread Fit: Provides tighter tolerances for secure, backlash-free connections in critical assemblies, enhancing overall system accuracy.
• Left-Hand Thread Design: Ideal for specialized applications where reverse threading prevents loosening from counter-clockwise motion, improving safety in rotating machinery.
• Knurled Socket Head: The knurled texture on the standard socket head allows for improved grip during installation, even with gloves or in oily conditions, speeding up assembly.
• Consistent Shoulder Dimensions: Features a 3/8" shoulder length with tight tolerances, ensuring precise alignment and smooth bearing surfaces in mechanical linkages.
• Environmental Compliance: Meets RoHS 3 and REACH standards, making it suitable for global supply chains and eco-conscious industrial projects.

Professional Applications & Engineering Value

This 4-40 UNC left hand thread shoulder screw is engineered to address common industrial challenges, such as misalignment and component wear in dynamic systems. The 18-8 stainless steel construction provides excellent corrosion resistance, crucial for machinery exposed to moisture or chemicals, while the Rockwell B55 hardness ensures longevity under repetitive stress. Its left-hand thread is specifically designed for applications where standard right-hand threads may loosen due to rotational forces, such as in conveyor systems or automotive assemblies. The 3/8" shoulder length acts as a precise pivot or spacer, reducing friction and maintaining alignment in linkages, bearings, and robotic arms. By integrating a Class 3A thread fit and knurled socket head, this screw delivers reliable, tool-friendly installation, minimizing downtime in high-precision environments like aerospace and medical equipment manufacturing.

Specification Summary & Compliance

This shoulder screw adheres to UNC coarse thread standards with a Class 3A thread fit for high precision. Dimensions include a shoulder diameter of 1/8" (tolerance: -0.004" to -0.002") and shoulder length of 3/8" (tolerance: -0.005" to 0.005"), ensuring consistent performance. It is manufactured in compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, supporting safe and sustainable industrial use.