011D
UNI 6954 - DIN 7981 - ISO 7049
PHILIPS PAN HEAD SELF TAPPING SCREWS 18 SERRATION TYPE CSelf-tapping screws are mainly used for screwing on metal sheets and laminates through simple drilling, without threading or tapping operations. These screws are not particularly suitable for use on die-cast materials and plastics. For safe and stable screwing, particular attention must be paid to the diameter of the hole to be made. A small hole in which the screw "forces" to enter is certainly not synonymous with a greater guarantee in fixing. Among other things, it should be remembered that the existing tables are empirical and only give an indication of drilling, but they are not a certain rule, as the fastening must be checked from time to time according to the technical-mechanical conditions of the part that will be tighten. 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 fixing 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 consideration that the serration can never replace the tightening of a screw with the serrated washer, which is much more efficient in itself. The length of the screw should be measured from the tip to the underhead.
