The right CNC plasma cutter has no problem cutting through thick plasma plate. However, it can be difficult to do the initial piercing when you first start cutting. Rooster tails look gorgeous in photos because the shower of sparks creates the appearance of something amazing happening.
However, shop managers cringe because they know material is being wasted. You can alternatively start from the edge, but again that wastes material.
So, here’s what you might do instead:
Use the Travel Piercing Technique
With this technique, you put your plasma torch in motion at a fast gouge speed. Then you slow the speed to a creep over a length of several inches, until the torch finally penetrates through the metal.
You can minimize that creep distance by raising the torch to a specific height and then lowering it to the cutting height.
This technique reduces waste. However, it still causes wasted material and leaves room for efficiency.
The “At the Nozzle” Technique
For starters, you can use a more pointed torch tip angle to combat blowback. This usually results in more slag hitting the surface of your torch.
Your torch may also have a water cooled shield cup. Shield cups keep spatter from hitting your CNC plasma cutter’s torch and solidifying to it.
When you’re inefficient with your piercing technique, regardless of the one you use, you end up with a molten pool of metal at the bottom of the hole you just pierced. You can overcome this problem with a “Double Pierce,” but you will need a power source with enough energy to pull it off.
With the “Double Pierce” technique, a plasma arc first partially pierces the metal’s thickness. Then the cutting stops, leaving what you call a blind hole.
Next, you scrape away spatter from the surface of the plate and reposition the plasma torch so it pierces about ¼” from the sidewall of the hole you just pierced.
This technique creates room for gases and molten metal to blow up and down the opposite sidewall of the blind pierce hole, eventually allowing the arc to penetrate to the bottom of your metal plate.
Choose the Best Technique for Your Shop
With these techniques in mind, it’s up to your operator to choose the right technique, or combination thereof. Regardless, they allow you to cut thick metal with minimal waste.