The difference between the two is that the implementation principle, usage scenario, installation method and fixing force are different.
1. Different implementation principle: the expansion part of the internal expansion screw is located inside the tubular expansion sleeve; the expansion part of the external expansion screw is located at the end of the thread.
2. Different usage scenarios: the internal expansion screw is suitable for soft base materials; the external expansion screw is suitable for hard base materials.
3. Different installation methods: Internal expansion screws require special tools to screw the threaded rod into the expansion sleeve and continue to rotate it with a wrench to expand and anchor the sleeve; external expansion screws only need to be screwed into the threaded hole with a screwdriver.
4. Different fixing force: Since the expansion part is located in different positions, the fixing force of internal expansion screws and external expansion screws is also different, and the fixing force of external expansion screws is more reliable.
