Why is it necessary to remove a chuck key before starting a machine?

Removing a chuck key before starting a machine is primarily related to safety and the prevention of accidents. A chuck key is used to tighten or loosen the chuck that holds the workpiece securely in place. If the chuck key is left in the chuck when the machine is started, it can become a dangerous projectile. The rotation of the chuck can cause the key to fly out, potentially injuring the operator or anyone nearby.

Thus, ensuring that the chuck key is removed before operating the machine is a critical safety protocol. This practice helps to create a safer working environment in the shop or factory. While other factors like preventing damage to the workpiece and enhancing machine performance may be concerns in an industrial setting, safety is the most immediate and pressing reason for this procedure.