Methods for operating a plasma torch

A method for piercing and cutting a workpiece using a plasma torch that includes an electrode, a nozzle, and a shield, the nozzle being spaced from and surrounding a distal end portion of the electrode to form a plasma gas flow channel, and the shield being spaced from and surrounding a distal end portion of the nozzle to form a shield flow channel, the method comprising:

• during a first time, delivering a plasma gas through the plasma gas flow channel and ionizing the plasma gas to produce a pilot arc;
• after the first time, delivering the plasma gas through the plasma gas flow channel to initiate a piercing operation that produces a pierce hole in the workpiece during a second time, the piercing operation extends across the second time and a third time;
• delivering, at the first time, a shield fluid through the shield flow channel at a first pressure;
• delivering, during at least a portion of the second time, the shield fluid through the shield flow channel at a second pressure, the second pressure being greater than the first pressure;
• during the third time, delivering the shield fluid through the shield flow channel at a third pressure that is different from the first pressure, the second pressure, or both the first pressure and the second pressure;
• and
• subsequent to the piercing operation, performing a cutting operation that forms a cut in the workpiece that originates at and extends away from a boundary of the pierce hole, wherein, during the cutting operation, the shield fluid is delivered through the shield flow channel at a shield cutting pressure substantially equal to or greater than the second pressure.

A method for piercing and cutting a workpiece using a plasma torch that includes an electrode, a nozzle, and a shield, the nozzle being spaced from and surrounding a distal end portion of the electrode to form a plasma gas flow channel, and the shield being spaced from and surrounding a distal end portion of the nozzle to form a shield flow channel, the method comprising:

• during a first time, delivering a plasma gas through the plasma gas flow channel and ionizing the plasma gas to produce a pilot arc;
• after the first time, delivering the plasma gas through the plasma gas flow channel to initiate a piercing operation that produces a pierce hole in the workpiece during a second time;
• delivering, at the first time, a shield fluid through the shield flow channel at a first pressure;
• delivering, during at least a portion of the second time, the shield fluid through the shield flow channel at a second pressure, the second pressure being greater than the first pressure;
• and
• subsequent to the piercing operation, performing a cutting operation that forms a cut in the workpiece that originates at and extends away from a boundary of the pierce hole, wherein, during the cutting operation, the shield fluid is delivered through the shield flow channel at a shield cutting pressure substantially equal to the second pressure.