Self Tapping screws are used in wood metal or plastic.
Self Tappers are used where there is access to only one side of the material being used, i.e. laying a deck or lining a wall. There are two basic types of self tappers, thread forming and thread cutting.
Countersunk Self Tappers are available in slot, pozi, phillips and square drives, the countersunk head allows for the user to achieve a flush finish with the surface of the material.
Undercut self tappers also known as Truncated self tappers are similar to countersunk only the head is undercut to around 70% of its normal side height.
Pan Head Self Tappers have a disc shaped head with chamfered edges and a flat base. Pan heads are available in pozi, slot, phillips and square drive and range in size from 2g x ¼' up to 14g x 4'.
Particle Board Screws have a countersunk head and are available in square drive. Particle Board screws have a thread cutting tip and a course thread.
Bugle Headed Decking Screws are also countersunk but their countersunk head has a more fluted shape similar to the shape of the stem of a wine glass.
Countersunk Slot Wood Screws are available in 18g (7.47mm) and 50mm to 120mm in length.
Hex Head Coach Screws are used to hold timber of larger proportions together where it is not practical to gain access to the reverse side to fit a nut. Identified by their nominal diameter length and grade.
Hex Head Self Tappers are similar to Coach screws with a hexagonal bolt like head but have a finer thread which runs the full length of the shank.
Hex Socket Head Self Tappers have a cap screw type head with a hex drive socket.