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Rackhams£5.19Visit shop Fixaball M4 Socket Cap Allen Screw Bolt High Tensile 12.9 Bzp - 4 - 12Mm
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The Range£7.46Visit shop Unifix Grade 12.9 Socket Head Cap Screws M5 X 10 - Box Of 200 - Grey
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The Unifix Grade 12.9 Socket Head Cap Screws DIN 912 are high-strength fasteners engineered for demanding mechanical and industrial environments where reliability and load-bearing capacity are critical. Designed for professionals and DIY enthusiasts working on heavy-duty projects, these screws offer exceptional tensile strength and ease of installation via a standard hex socket drive. The primary caveat to consider is that their high-grade steel composition may be susceptible to surface oxidation if used in highly corrosive or outdoor environments without proper protective coating or maintenance.
| Colour | Silver |
|---|---|
| Model Part Number | DIN 912 |
| Brand | Unifix |
Grade 12.9 refers to the strength class of the bolt, indicating a tensile strength of 1200 MPa and a yield strength of 1080 MPa, making them exceptionally strong.
They are primarily designed for internal or controlled-environment use. For long-term outdoor exposure, consider a stainless steel alternative or ensure they are treated with a heavy-duty rust inhibitor.
Yes, you need a standard hexagonal key (Allen key) or a corresponding hex drive bit compatible with the bolt size.
Yes, because they are made from high-carbon, high-strength alloy steel, they are magnetic.
If the bolt has not been stretched beyond its yield point, you can reuse it; however, for critical structural or safety-related applications, it is always best practice to use new fasteners.
Verify that the thread pitch matches the tapped hole and ensure no debris or metal shavings are inside the threads.
The hex key may be worn or undersized. Use a new, high-quality metric hex key that fits perfectly into the socket.
Clean the surface with a wire brush, apply a light coat of machine oil or rust-inhibitor, and consider replacing with a stainless steel alternative if the environment remains damp.
For optimal performance, always match the thread pitch of the screw with the corresponding internal thread or nut. When installing, use a high-quality hex key or socket bit that fits snugly to avoid stripping the interior drive. While the Grade 12.9 finish is durable, applying a thin layer of machine oil or anti-seize compound before installation can protect the threads from galling and provide a slight barrier against surface corrosion. If the screws are used in an environment exposed to humidity, periodic inspections for signs of oxidation are recommended, and they should be replaced immediately if rust or significant structural deformation is observed.
