Final answer:
The contact tip of a MIG welding gun is fastened to the nozzle or gas diffuser. The nozzle or gas diffuser directs the shielding gas and protects the welding pool. Fastening the contact tip to the nozzle ensures a stable electrical connection.
Step-by-step explanation:
The contact tip of a MIG welding gun is fastened to the nozzle or gas diffuser.
The nozzle or gas diffuser is a component of the MIG welding gun that directs the shielding gas to protect the welding pool from atmospheric contaminants.
By securely fastening the contact tip to the nozzle or gas diffuser, the contact tip becomes an integral part of the welding torch and ensures a stable electrical connection between the wire electrode and the welding gun.