The knurling under the head has two distinct functions. Once the screw has been tightened, the indentation causes the unscrewing torque used to be greater, making the fastening more stable in all those applications that are subjected to movements and / or vibrations during their use. In the electric field, on the other hand, the indentation scrapes the surface of the metal effectively creating connectivity with the material where grounding is required. However, it must be taken into account that the serration can never replace the tightening of a screw with the serrated washer, which is much more efficient in itself.
The large head favors a wider sealing surface as well as the possible covering of through holes in the case of sandwich coupling between two sheets, while the low profile and without edges makes them particularly suitable for "visible" applications. This screw has wide fields of application ranging from the mechanical sector to the household appliance, from automotive to aluminum window frames.
The length of the screw should be measured from the tip to the underhead.
VITI AUTOFILETTANTI SPECIALI 4.3X 13 TFU+ DENT. TROPICAL
VITI AUTOFILETTANTI BREVETTATE 4.3X 13 TFU+ DENT. ZINCATE Cr.3