Special low head screw NYLOK

a) ISO 7380-2 specifies the standard for hexagon socket button head screws with collar. Generic hexalobular socket (6 lobe) is another common alternative used in various applications. 

b) This screw features an extended cylindrical tip, known as a dog point, at the end of the threaded portion, enabling precise alignment and positioning in mating components.

Serrations under head / Hexalobular socket ISO 10664

a) DIN 968 specifies the standard for cross-recessed pan head tapping screws with a collar. The screws are commonly available with two types of cross recess drives: Type H (Phillips) and Type Z (Pozidriv), both designed for easy installation and removal.

b) There are two types of thread ends specified in DIN 7970 (Tapping Screws): Type C, which features a cone point, and Type F, which has a flat end.

Square neck under head

a) DIN 7500 specifies self-tapping screws for metal, also known as thread-forming screws. These screws are designed to form or cut threads in a pre-drilled hole in metal materials, without requiring a pre-cut thread.

b) The screw shank has a three-lobe shape instead of a round cross-section, which reduces friction during installation, and facilitates smooth material displacement and efficient thread formation.

c) The long dog point (the extended, unthreaded tip of the screw) acts as a pilot, helping to align the screw with the pre-drilled hole during installation, and faciliates smooth installation.

d) A standard trilobe thread forming screw without dog point is avaialble upon request.

a) A self-drilling screw is a type of screw designed to drill its own hole and tap its own threads into materials as it is driven in, eliminating the need for a pre-drilled hole. The screw features a drill-like tip, often referred to a self-drilling tip, which helps the screw cut through the material. This makes installation faster and more efficient. 

b) Serrations under head create additional friction between screw head and the material. The serrated surface provides better grip for tools like screwdrivers, allowing more torque to be applied during installation.