Metric A4 (316) Stainless Steel Cup Point Socket Set Screws
A4 stainless steel cup point set screws deliver the holding power of a standard grub screw with the superior corrosion resistance needed for marine, chemical, and high-humidity environments. Manufactured from 316 stainless steel, these headless fasteners resist chlorides, saltwater, and aggressive chemicals that would compromise standard 18-8 grades. The cup point tip creates a shallow circular impression in the mating surface, generating strong rotational grip that holds firm under vibration and dynamic loading. Whether you are securing shaft-mounted components on a commercial vessel or locking adjustment mechanisms in a food processing line, A4 cup point set screws provide long-term reliability without sacrificing holding force.
How Cup Point Set Screws Work
Cup point set screws, also called grub screws or headless set screws, thread completely into a tapped hole until the tip contacts the mating surface. The cup point design features a shallow concave recess ringed by a sharp circular edge. As the screw is tightened with a hex socket key, this edge bites into the shaft or component surface, creating a small indentation that resists rotational movement. This mechanical interlock makes cup points one of the most effective set screw tip styles for preventing slippage on hardened or semi-hardened surfaces. Because the fastener sits flush or below the surrounding surface, it eliminates snag points and allows unobstructed movement of adjacent parts.
Why Choose A4 (316) Stainless Steel
A4 stainless steel, also known as 316 stainless, contains molybdenum that significantly improves resistance to pitting and crevice corrosion from chlorides and marine atmospheres. Where standard A2 (18-8) stainless may develop surface corrosion in saltwater or chemical environments, A4 grade maintains its integrity and appearance over extended service life. This makes A4 cup point set screws the preferred choice for applications where fastener replacement is difficult or costly, and where contamination from corroding hardware is unacceptable. The higher nickel and molybdenum content also provides better performance at elevated temperatures compared to standard austenitic grades.
Material Specifications
These set screws are manufactured to DIN 916 standards from A4 (316) stainless steel. The 316 designation indicates a minimum chromium content of 16%, nickel content of 10%, and the addition of 2% molybdenum for enhanced corrosion performance. A4 stainless provides tensile strength in the range of 500–700 MPa, suitable for the clamping and positioning applications where set screws are typically deployed. The material is non-magnetic in its annealed state and maintains corrosion resistance across a broad temperature range, making it appropriate for both cryogenic and moderately elevated temperature environments.
Cup Point vs. Other Set Screw Tips
Set screws are available in several tip configurations, each suited to different holding requirements. Cup point set screws offer the best general-purpose grip on hardened and semi-hardened shafts thanks to the sharp-edged recess that bites into the surface. Cone point set screws provide the strongest permanent hold by penetrating deeply into softer materials or pre-drilled recesses, but they create a more significant surface mark. Dog point set screws feature a flat cylindrical extension that fits into a machined slot for precise positioning without surface damage. Knurled point set screws use a textured tip for moderate grip on softer materials where surface marring should be minimized. For marine and chemical environments where you need reliable grip without permanent shaft damage, A4 cup point set screws strike an effective balance between holding force and surface preservation.
Common Applications
- Marine & Coastal – Securing hardware on boats, docks, offshore platforms, and desalination equipment exposed to saltwater
- Food & Beverage Processing – Locking adjustment collars and rollers on washdown-rated equipment where hygiene and corrosion resistance are essential
- Chemical & Pharmaceutical – Fastening components in chemical processing plants, laboratories, and pharmaceutical manufacturing lines
- Medical & Laboratory – Positioning precision components in medical devices, diagnostic instruments, and laboratory fixtures
- Automotive & Motorsports – Securing pulleys, gears, and collars on performance and custom vehicles where corrosion resistance extends service life
- Industrial & Manufacturing – General machinery assembly in humid or chemically aggressive factory environments
- OEM & Custom Fabrication – Specifying marine-grade fasteners for equipment designed for corrosive or outdoor deployment
Available Sizes
AlbanyCountyFasteners.com stocks A4 (316) stainless steel cup point socket set screws across a range of metric diameters and lengths to accommodate everything from precision instrument assemblies to heavy-duty marine hardware. Sizes follow standard DIN 916 metric coarse thread specifications. Browse the listings below to find the specific diameter and length combination for your application.
Need help selecting the right cup point set screw for your project? With over 18 million fasteners in stock and competitive bulk pricing, Albany County Fasteners is ready to help. Contact our team for technical assistance, volume quotes, or to discuss your specific marine-grade fastener requirements.