Plasma cutting can feel complicated when you first encounter values such as amperage, feed rate, pierce delay, air pressure, and torch height. Fortunately, you do not need to guess every value. Begin with a reliable cut chart, understand what each setting controls, and make small adjustments based on what the finished edge tells you.
The Five Main Plasma-Cutting Settings
The most important process settings are:
- Cutting amperage
- Feed rate
- Pierce delay
- Gas or air pressure
- Torch height
These settings work together. Increasing amperage without changing the nozzle, speed, or torch height can produce a wider kerf, more bevel, heavier dross, or shorter consumable life. Treat the process as one system rather than five unrelated numbers.
Start With the Correct Cut-Chart Profile
A cut chart is a tested collection of settings for a particular plasma source, torch, consumable set, material, thickness, amperage, and gas. Two machines rated at 85 amps may behave differently because their torches, nozzle geometry, gas control, and arc characteristics are not identical.
When the exact manufacturer chart is unavailable, another manufacturer’s chart can provide a useful starting point—but it must be labeled as a reference and confirmed with test cuts.
The Plasma Cut Lab calculator distinguishes official manufacturer profiles from generic or machine-specific reference profiles so the source of the recommendation remains clear.
Step 1: Select the Material
Begin by selecting the material being cut:
- Mild steel
- Stainless steel
- Aluminum
All three can be cut using compressed air, but their recommended speeds and cut behavior are not identical. Industrial systems may also use oxygen, nitrogen, F5, argon-hydrogen, or other gas combinations. Never mix values from a specialized-gas chart into an ordinary compressed-air process.
Compressed air must be clean and dry. Water, oil, or debris can reduce cut quality and shorten the life of the electrode and nozzle.
Step 2: Enter the Actual Material Thickness
Measure the plate when accuracy matters. Material sold as 6 mm may measure slightly above or below its nominal size, especially when coatings or mill scale are present.
The calculator accepts millimeters or inches and displays the result in both unit systems. When an exact thickness is not in the chart, it may interpolate between neighboring rows only when the material, amperage, torch family, and gas process match.
Step 3: Choose the Cutting Amperage
A common beginner mistake is running the plasma cutter at maximum amperage for every job. An 85-amp machine does not need to cut every plate at 85 amps.
Lower-current processes are often preferable on thin material because they can provide:
- A narrower kerf
- Better detail
- Less heat input
- Cleaner edge quality
- Longer consumable life
Higher amperage becomes useful as the plate becomes thicker or when the chart calls for a faster production process.
Machine Maximum Versus Cutting Amperage
The machine maximum is a capacity limit. Cutting amperage is the process current selected for the material and thickness.
Always install consumables rated for the selected process. A 45-amp nozzle should not be operated at 85 amps.
Step 4: Set the Feed Rate
Feed rate is the speed at which the torch travels across the plate. It has a major effect on dross, edge angle, kerf width, and dimensional accuracy.
Too slow
- Thick, bubbly bottom dross
- Wider kerf
- Excessive heat input
- Rounded or melted details
Too fast
- Narrow kerf
- Heavily angled edge
- Trailing or curved drag lines
- Hard bottom bead or incomplete cut
Quality, Balanced, and Speed Priority
Quality Priority favors edge finish, detail, and dimensional accuracy.
Balanced is the recommended starting point for most users.
Speed Priority favors production rate, but should remain within the tested chart range.
Try the calculator with your material and thicknessStep 5: Set the Pierce Delay
Pierce delay is how long the torch remains at the starting point before cutting motion begins. The arc needs enough time to penetrate the plate completely.
Delay too short
- The plate may not fully pierce
- The first part of the profile may remain attached
- Molten material may be dragged into the cut
Delay too long
- The pierce hole grows unnecessarily
- Molten metal blows back toward the torch
- Consumable life can decrease
Start with the chart value and change it in small increments. A few tenths of a second can make a noticeable difference.
Step 6: Set the Gas or Air Pressure
On an air-plasma system, compressed air:
- Helps form and constrict the plasma arc
- Removes molten metal from the kerf
- Cools torch components
- Supports consumable performance
Some machines require manual pressure adjustment. Others regulate pressure automatically. Use the setting specified for the selected machine rather than copying a pressure from an unrelated plasma cutter.
A regulator can show acceptable pressure while the compressor cannot supply enough liters per minute or cubic feet per minute during a long cut. Check pressure while air is flowing.
Step 7: Confirm Torch Height
Torch height is not yet part of the first calculator version, but it is one of the most important settings in mechanized plasma cutting.
Pierce Height
The torch normally begins the pierce farther away from the plate to reduce molten-metal blowback toward the shield and nozzle.
Cut Height
After the pierce, the torch lowers to the cut height. Incorrect height can cause bevel, poor arc stability, a wider or narrower kerf, increased dross, and faster consumable wear.
On a CNC table with torch-height control, arc voltage is commonly used to maintain the desired torch-to-plate distance as the plate moves or warps.
Run a Test Coupon Before the Final Part
Even a manufacturer chart is a starting point for your particular table, air system, material batch, and consumables. Before cutting an expensive part, test on a small piece of the same material.
A useful coupon includes:
- A straight line
- A square
- A circle
- A small internal hole
- Several lines at slightly different speeds
- Begin with the calculated settings.
- Confirm that the plate pierces completely.
- Inspect the bottom dross.
- Look at drag-line direction and edge bevel.
- Measure the kerf.
- Change only one setting at a time.
- Record the cleanest result.
Read What the Finished Edge Is Telling You
| Observation | Possible cause | First adjustment |
|---|---|---|
| Thick, bubbly bottom dross | Feed rate too slow | Increase speed slightly |
| Small, hard bottom bead | Feed rate too fast | Reduce speed slightly |
| Heavy top spatter | Speed too slow or torch too high | Verify speed and height |
| Strong edge bevel | Incorrect height or excessive speed | Verify height, then speed |
| Cut does not penetrate | Current too low, speed too high, or low airflow | Check amperage, speed, and airflow |
| Large damaged start point | Delay too long or pierce height too low | Reduce delay or verify height |
| Incomplete start point | Pierce delay too short | Increase delay slightly |
A Simple Beginner Workflow
- Select the correct machine or reference profile.
- Select mild steel, stainless steel, or aluminum.
- Enter the measured material thickness.
- Enter the machine’s maximum amperage.
- Select Quality, Balanced, or Speed priority.
- Calculate the starting settings.
- Install the correct amperage-rated consumables.
- Confirm air pressure and airflow.
- Verify pierce height and cut height.
- Run a test coupon.
- Change only one setting at a time.
- Save the final settings for future jobs.
Final Thoughts
Choosing plasma-cutting settings is not about finding one universal formula. It is about matching the material, thickness, torch, consumables, amperage, speed, pressure, delay, and height as one complete process.
Begin with a trusted chart or clearly labeled reference profile. Use the calculator to organize the starting values, then confirm them through controlled test cuts. The more results you record, the more accurate your own machine-specific chart becomes.
Calculate your starting point
Ready to choose your settings?
Select the material, thickness, machine capacity, profile, and cutting priority. The calculator displays feed rate in mm/min and IPM, pierce delay, gas pressure, and cutting amperage.
Open the plasma calculator