Self-drilling screws are distinguished by having an effective drill bit at the tip of the screw.
The applications of the hex self-drilling screws can vary - the smaller screws are used in applications like fixing thin gauge metals and fixing metal to wood. The larger screws are used in roofing and other industries which require self-drilling through tough metals.
Self-drilling screws can be used with or without washers depending on your needs, but there are certain situations where they require the use of a washer.
Indented hex head screws have an indented top surface, six flat sides, and a flat bearing surface. They are preferred in high-volume assembly applications where pneumatic equipment is used to drive the screw. The indented hex style can transmit higher tightening torque levels than other head styles.
