The difference between self-tapping screws and non-self-tapping screws

The main difference between self-tapping screws and non-self-tapping screws lies in their thread design and how they create threads in the material they are being driven into.

1. Self-Tapping Screws: Self-tapping screws have a sharp, flute-like thread design that enables them to tap their own threads as they are driven into the material. The screw's threads are designed to cut into the material, displacing it and creating corresponding threads. This eliminates the need for pre-drilling a pilot hole in many cases, as the self-tapping screw can create its own hole and threads as it is installed.

Self-tapping screws are often used with materials such as thin metals, plastics, and wood. They provide a fast and efficient way to join materials without the need for additional steps like drilling pilot holes. However, it's important to select the correct self-tapping screw based on the material and application to ensure proper thread engagement and holding power.

2. Non-Self-Tapping Screws: Non-self-tapping screws, also known as machine screws or thread-forming screws, do not have a cutting thread design. Instead, they have a thread-forming thread design. When driven into the material, non-self-tapping screws displace the material rather than cutting or removing it to create threads.

Non-self-tapping screws are typically used with materials such as metal, where pre-drilling a pilot hole is necessary to create a starting point for the screw. The pilot hole should be smaller in diameter than the screw's outer diameter, allowing the screw's threads to engage the material and form threads as they are driven in.

Compared to self-tapping screws, non-self-tapping screws often provide a more secure and precise thread engagement in harder materials. They are commonly used in applications where high torque or load-bearing capabilities are required.

It's important to note that the selection of self-tapping screws or non-self-tapping screws depends on the material, application, and specific requirements of the project. Consider factors such as material hardness, desired thread engagement, and load-bearing capacity when choosing the appropriate screw type.