How can I cut better holes?
The first step is to set realistic expectations. Although plasma can produce excellent quality holes, those holes need to be sized correctly. The general rule is to use a one-to-one thickness-to-hole ratio. This means using 1/4” thick plate for 1/4” holes, 1/2” plate for 1/2” holes, etc. Following that rule, the key to good holes is as follows:
- Use the lowest power consumables that will cut your thickness.
- Start your lead in at the very center of the hole, so the torch has time to index from pierce height to cut height before reaching the radius of the hole.
- Don’t program a lead-out; instead, use an overburn technique in which you go 0.100" past the lead-in kerf, staying on the hole radius.
- Slow down, especially if cutting holes smaller than 1” in diameter. The feed rate for holes under 1" should be 60% of the feed rate suggested in the manual for cutting that thickness at the power level.
- Use a good height control. This is critical! You cannot cut consistently good holes without a properly functioning height control.
These tips will improve hole quality when using most plasma systems; however, for the very best plasma hole quality, you will want to use Hypertherm's True Hole™ technology, available only with HyPerformance® plasma. This fully automates hole cutting by eliminating taper and start/stop dings and divots, without any operator intervention.