S-91870A120 4-40 x 5/16" ASME B18.3 Tamper-Resistant Torx Stainless Steel Flat Head Screws
Tamper-Resistant Torx Stainless Steel 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
- Enhanced tamper resistance with T8 drive style prevents unauthorized removal in high-security applications
- Superior corrosion protection through 18-8 stainless steel construction and passivated finish for extended service life
- Reliable high-strength performance with 70,000 psi tensile strength and Rockwell B70 hardness for demanding environments
- Precision thread engagement with Class 2A UNC coarse threads ensuring consistent fastening and vibration resistance
- Optimized flush mounting featuring standard 82° countersink angle and flat head design for smooth surface finishing
- Full regulatory compliance meeting ASME B18.3 standards and RoHS/REACH environmental regulations
- Complete threading coverage across the 5/16" length provides maximum grip strength in various material thicknesses
Professional Applications & Engineering Value
These 4-40 UNC flat head screws deliver exceptional engineering value in applications where security, corrosion resistance, and reliable fastening are critical. The combination of 18-8 stainless steel material and passivated finish creates a robust barrier against corrosive environments, making them ideal for electronic enclosures, medical devices, and outdoor equipment. The tamper-resistant T8 drive system provides crucial security where unauthorized access must be prevented, while the Class 2A thread fit ensures precise engagement and vibration resistance in assembly operations. The 82° countersink angle and flat head profile allow for flush mounting in precision applications, eliminating protrusions that could interfere with mechanical operation or create safety hazards.
Specification Summary & Compliance
Manufactured to exacting ASME B18.3 specifications with Class 2A thread fit tolerance for consistent performance. Features 4-40 UNC coarse threads with right-hand orientation and full threading along the 5/16" length. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use in regulated industries and international markets.
