It follows that the operator must estimate the tonnage required to form a part before making the first bend. Of course, this is critical only if the operator is bottom-bending or coining. You can't exceed the tonnage limit during air bending. Only during bottom bending or coining can the tonnage applied escalate to the rated tonnage of the machine.

Tonnage charts are available from all press brake manufacturers, and charts sometimes are mounted on the press brake itself. Keep in mind, however, that tonnage charts are for air bending only. To use the chart to estimate tonnage for bottoming or coining, simply multiply the air bend tonnage by 4 for bottoming and by 8 for coining.

Sometimes it is better to form a part off-center if your press brake can do this. Check with the manufacturer of your machine before attempting this, though. If a machine is not designed for off-center loading, you can damage it severely if you try it.

Maintenance. In addition, operators should know all of their machine's maintenance requirements. This includes periodic oil and filter changes (for hydraulic machines), regular lubrication, and proper machine level. Even if maintaining the machine isn't the operator's responsibility, he should at least be familiar with the procedures.