M2.5 M3 M4 Hexagon Socket Head Metal Screws With Waisted Shank DIN796(E) Stainless Steel A2-70 A2-80 A4-70 A4-80 Plain Polished

Non-detachable bolts, also known as anti-drop bolts or self-locking screws, are designed to remain securely fastened to equipment even when loosened or removed. Their key feature is that they will not fall off the mounting plate or equipment even if they are not fully tightened, thereby reducing the risk of the bolt being lost or falling into the equipment and causing a short circuit or damage.

This waisted shank hexagon socket head cap screw conforms to DIN796(E), featuring a reduced diameter section (waist) between the head and the threaded portion. The waist is smaller than the thread root diameter, allowing controlled elastic deformation under cyclic or impact loads, which significantly improves fatigue life. The standard hex socket head enables high torque application using hex keys. Manufactured from premium stainless steels: A2-70 (304), A2-80 (high-strength 304), A4-70 (316), and A4-80 (high-strength 316). The plain polished finish provides a bright, corrosion-resistant surface. Sizes M2.5, M3, and M4 are ideal for precision machinery, electronics, and instruments where enhanced fatigue resistance is required.

• Precision drive train components – small reducers, stepper motor mounts.

• Medical devices (non-implantable) subjected to cyclic vibration.

• Drone and RC model propeller mounts – waist absorbs landing shocks.

• Optical instrument adjustment stages – A4-80 offers non-magnetic, high strength.

• Automation equipment sensor brackets.

• Waisted shank design – greatly improves fatigue performance under dynamic loads.

• Polished stainless steel – aesthetically pleasing, corrosion-resistant, coating-free.

• Multiple strength grades – A2-80/A4-80 for higher preload.

• Small precision sizes – M2.5–M4 suit miniaturised equipment.

• DIN796 compliance – defined waist geometry ensures reliable behaviour.