In this phase, an External Shot Blast device is used to clean oxidized particles from outside surface of the cylinders.

When the cylinder enters the machine , it turns and goes forward to the attack cabin. Two turbines are used to strew the shot on the outside surface of cylinders. 

This is called cleaning process and the whole process takes about 6 minutes.

The External Shot Blast is used twice in the whole process. Once after the hardness test and once before the painting process.