Hypertherm HPR260 Manual Gas Preventive Maintenance Program Rev.5 - Manual (Page 142)

OPERATION
4-48 HPR260 Auto Gas Instruction Manual
How to optimize cut quality
The following tips and procedures will help produce square, straight, smooth and dross-free cuts.
Tips for table and torch
• Use a square to align the torch at right angles to the workpiece.
• The torch may travel more smoothly if you clean, check and “tune” the rails and drive system on the cutting table.
Unsteady machine motion can cause a regular, wavy pattern on the cut surface.
• The torch must not touch the workpiece during cutting. Contact can damage the shield and nozzle, and affect
the cut surface.
Plasma set-up tips
Follow carefully each step in the Daily start-up procedure described earlier in this section.
Purge the gas lines before cutting.
Maximize the life of consumable parts
Hypertherm’s LongLife ® process automatically “ramps up” the gas and current flows at the start and ramps them down
at the end of each cut, to minimize erosion of the electrode’s center surface. The LongLife process also requires that
cuts start and stop on the workpiece.
• The torch should never fire into the air.
– Starting the cut at the edge of the workpiece is acceptable, as long as the arc is not fired in the air.
– To start with a pierce, use a pierce height that is 1.5 to 2 times the torch-to-work distance. See Cut charts.
• Each cut should end with the arc still attached to the workpiece, to avoid arc blow-outs (ramp-down errors).
– When cutting drop parts (small parts that drop down after being cut from the workpiece), check that the arc
stays attached to the edge of the workpiece, for proper ramp-down.
• If arc blow-outs occur, try one or more of the following:
– Reduce the cutting speed during the final part of the cut.
– Stop the arc before the part is completely cut, to allow completion of the cut during the ramp-down.
– Program the path of the torch into the scrap area for ramp-down.
Note: Use a “chain cut” if possible, so the path of the torch can lead directly from one cut part into
the next, without stopping and starting the arc. However, do not allow the path to lead off the
workpiece and back on, and remember that a chain cut of long duration will cause electrode
wear.
Note: It may be difficult to achieve the full benefits of the LongLife process in some conditions.