S-91512A190 1/4"-20 x 1/2" Left-Hand-Thread Stainless Steel Hex-Drive Flat Head Screws
Left-Hand-Thread Stainless Steel Hex-Drive Flat Head Screws
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Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
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Key Features & Benefits at a Glance
- Superior corrosion resistance with 18-8 stainless steel construction and passivated finish, ideal for harsh environments
- Exceptional mechanical strength offering 70,000 psi tensile strength and Rockwell B70 hardness for reliable, long-term performance
- Precise Class 3A thread fit ensures secure fastening and vibration resistance in critical assemblies
- Left-hand threading provides counter-rotational security for specialized machinery and safety applications
- Standard 82° countersink angle allows for flush mounting, reducing protrusion and improving aesthetics
- Easy installation and removal with 5/32" hex drive, minimizing tool slippage and assembly time
- Full regulatory compliance with RoHS 3 and REACH, ensuring safe use in regulated industries
Professional Applications & Engineering Value
These 1/4"-20 UNC left-hand thread flat head screws are engineered to address common industrial challenges, such as loosening under counter-clockwise motion and corrosion in demanding environments. The 18-8 stainless steel material combined with a passivated finish significantly enhances durability against moisture, chemicals, and oxidation, making them suitable for marine, chemical processing, and outdoor equipment. The left-hand thread direction is critical for applications where reverse rotation could cause components to detach, such as in rotating machinery, mixing equipment, and safety-critical assemblies. With a coarse UNC thread and full threading, they provide quick installation and high clamping force, reducing maintenance frequency and improving operational reliability in industrial screws applications.
Specification Summary & Compliance
This screw adheres to UNC coarse thread standards with a precise Class 3A thread fit for tight tolerances and reliable engagement. Dimensions include a 1/4"-20 thread size, 1/2" length, 0.531" head diameter, and 82° countersink angle. Manufactured from 18-8 stainless steel with a passivated finish, it meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance, ensuring environmental and safety standards for industrial use.
