S-91518A130 M4 x 8 mm 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 and passivated finish, ensuring longevity in harsh industrial environments.
- Reliable reverse-thread performance with left-hand threading, ideal for applications requiring counter-clockwise tightening to prevent loosening.
- High mechanical strength offering 70,000 psi tensile strength and Rockwell B70 hardness for durable, vibration-resistant fastening.
- Easy installation and removal using a standard 2.5 mm hex drive, reducing assembly time and tool wear.
- Precise thread fit with Class 6g coarse threads, ensuring consistent engagement and reducing cross-threading risks.
- Flush mounting capability with a standard 90° countersink flat head, providing a smooth surface finish in assembled components.
- Full compliance with environmental standards including RoHS 3 and REACH, supporting safe and sustainable manufacturing practices.
Professional Applications & Engineering Value
This M4 left-hand metric flat head screw is engineered to address critical challenges in machinery and equipment where standard right-hand threads may loosen under rotational forces. Constructed from 18-8 stainless steel with a passivated finish, it resists corrosion and chemical exposure, making it suitable for automotive, aerospace, and marine applications. The left-hand thread direction provides secure fastening in reverse-thread mechanisms, such as rotating shafts or opposing motion assemblies, while the hex drive and coarse thread pitch enable quick installation in high-vibration environments. Its fully threaded design and Class 6g fit ensure uniform load distribution, reducing stress concentrations and enhancing joint integrity for long-term reliability.
Specification Summary & Compliance
This screw meets precise dimensional standards with a Class 6g thread fit and metric coarse threading (M4 x 0.7mm), ensuring compatibility with ISO metric components. Manufacturing adheres to industry specifications for flat head profile and 90° countersink angle. It is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing the absence of hazardous substances for safe industrial use.
