Lockout/ Tagout Case Study - Robot Arm murder incident

Robot arms are widely used in auto parts manufacturing plants. They are usually housed in enclosures. Suspended parts are transferred from one site to another in a production location by rotating tables while the parts are lubricated and operated by robotic arms.

If necessary, employees can access the cage through an electrically interlocked door, giving them access to the robot arm. When the gate is opened, the multiple sources of energy that power the robot arm, rotary table and associated machinery are closed, but not powered or locked.

When the arm is activated, an employee in the cage can be hit by the arm or other machine parts and seriously injured. Injuries occur when an employee enters the robot arm cage without powering off or locking any equipment, as the employer did. The employee is trying to unblock the robot arm. While releasing the arm, the employee tripped over the electric eye, causing the arm to circulate. The employee was hit in the arm by the robot arm and injected with oil.

The Lockout/tagout procedure is necessary because once the door is open, it is impossible for the robot arm to move, and the maintenance worker in the cage is fully warned by closing the interlock door before the machine is activated to avoid injury.