How to distinguish between self-tapping screws and wood screws?

It is important to choose a suitable lubricant in tapping. When cleaning is not required, use a self-cleaning tapping lubricant. For difficult-to-machine workpieces, pure oil tapping oil is required.
1. Screw: It is also a type of fastener composed of two parts: head and screw. According to the purpose, it can be divided into three categories-machine screws, set screws and special purpose screws.
Machine screws are mainly used for a fastened connection between a part with an internal threaded hole and a part with a through hole, without the need for nut cooperation (this type of connection is called a screw connection, which is also a detachable connection; It can be matched with a nut to fasten the connection between two parts with through holes. The set screw is mainly used to fix the relative position between the two parts. The special purpose screw has a ring screw for lifting parts
2. Self-tapping screws: similar to machine screws, but the thread on the screw is a special self-tapping screw thread. It is used to fasten and connect two thin metal components to make them into a whole. Small holes need to be made in the components in advance. Because this kind of screw has high hardness, it can be directly screwed into the hole of the component to make the component hole Form the corresponding internal thread. This connection form is also a detachable connection
3. Wood screws: also similar to machine screws, but the thread on the screw is a special wood screw thread, which can be directly screwed into the wooden component (or part) to use a metal (or non-metal) with a through hole The parts are firmly connected to a wooden component. This connection form is also a detachable connection.