Self tapping screws generally refer to pointed, coarse toothed, and harder wood screws, as well as aluminum alloy and plastic screws. A special self tapping screw used for threading metal holes is called a tap. The hole of a self tapping screw drill is a hole that does not require tapping teeth. The screw used is different from ordinary ones, with a pointed head and a relatively large pitch, similar to a chip free screw drill. It can be directly screwed in without tapping teeth. This method is commonly used for metals and plastics. Self tapping screws can use their own threads to "drill, squeeze, and press" the solidified material into corresponding threads, making them tightly fit each other.