How to best set your plasma cutter for cutting metal?

A plasma cutter passes through metal like a hot knife through butter. It cuts through metal without much resistance because of the unique properties of plasma. Fabrication and welding of metal often uses plasma cutters. Conceptually, plasma cutters are easy to learn and use. However, first time operating a plasma cutter it isn’t a simple plug in and use. It’s wise to take time to learn the workings of plasma cutter and understand how it best performs.

Many users underestimate the value of taking time to read and acquaint them with their particular plasma cutter.The owner’s manual contains vital information for the optimal working of the plasma cutter. When operating, the plasma cutter produces cutting sparks and fumes that may be hazardous to your health.

Before using the plasma cutter make sure to routinely check all the settings, starting at the back of the machine going to the front. Depending on the thickness of the metal, it is important to make sure that the settings of the plasma cutter are adjusted to make sure you get the right output.Here are some best practices that will help increase the efficacy and the precision of the plasma cutter, which will help you make the best cuts:

  1. Ensure that the power is in a good condition. Plug into the right type of primary power supply. Some units require a specific voltage while others allow you to plug them into any power supply from 208 to 575 V. It is up to the user to make sure that the machine is plugged into the correct power supply and switch on any other power selections.
  2. Air pressure is a vital aspect when operating a plasma cutter. When there is an increase in air pressure it can spew out the plasma; not enough air pressure it can’t cut anything –it will just melt the metal into blob or slag. The plasma cutter’s manual should mention the air requirements. Check your air supply to make sure you have proper air flow and pressure entering the machine for quality operation.
  3. Fit the torch to the connection, if it isn’t connected to the machine. Make sure to screw the torch connection securely but do not overtighten it.
  4. Check that all the consumables such as the electrode, gas distributor, tip and the shield cup are in place and fitted correctly for the job. Overtightening the shield cup can result in intermittent cutting.
  5. Dry air maximizes cutting capacity of the cutter. Compressed air is contaminated by moisture and oil residue. Contaminants can shorten the life span of the torch and consumables. If it is not equipped with an air filter or dryer install it on the machine. Clean, and replace the filter/dryer as recommended by the manufacturer. To decrease air pressure leak, it’s necessary to have some sort of sealant on the connection.
  6. Proper grounding is extremely important for plasma cutting. If there isn’t proper grounding, the plasma arc will not be able to sustain itself. Check the ground connection to the machine.
  7. Check the air setting. The pounds per square inch (PSI) setting are different for cutting and gouging. Set the output to the correct setting.
  8. Rehearse the cut and ensure that one continuous cut can be made. To make a long clean cut, the operator cannot stop and then continue.Making a sample cut on the same type of metal as you are going to be working on to check the machine settings and cutting/ travel speed.

A clean cut is dependent on amperage and air pressure settings, using the right consumables,travel speed and direction and technique.

Check Air Pressure and Amperage settings

To get an optimal output out of the machine, it is necessary to adjust the settings on the plasma cutter. It is necessary to select the correct air pressureand air flow rate, which is usually, set around 60 psi. The other adjustment which is vital is the amperage setting. Using a plasma cutter on a lower amperage will barely cut into the metal whereas on ahigher setting, will result in irregular cuts with lots of slag on metals. Most plasma machines work well on lower amperage but selecting the right air pressure is the key to getting the best cut. The plasma cutter manual will specify the optimal air pressure.

Travel speed when cutting the metal

On thicker metal, set the cutter to its maximum output and vary your travel speed. Metals like aluminum, the faster it is cut, cleaner the cut will be.On thinner material, it’s necessary to turndown the amperage and change to a lower-amperage tip to maintain a narrow kerf. The arc should exit the metal at a 15- to 20-degree angle opposite the direction of travel. If the plasma arc is going straight down, it is going too slowly, and there will be an unsightly amount of dross. It will spray backward, if it’s cutting too fast.

Using the Right Consumables

Some plasma cutters use separate tips for the high and low end of their amperage ranges. When the plasma cutter is used to cut thick material, the higher amp tip is used. To maintain a thin kerf when cutting thin metal sheets,it’s necessary to set the machine to lower-range amperage and use a low-amp tip. A low-amp tip has a smaller orifice, it produces anarrow plasma. When a 40-amp tip is used for an 80-amp setting will destroy the tip orifice and reducing its life.

Working without a drag shield in place, and when the 1/16- to 1/8-inch distance between the tip and the metal is not maintained it causes double arcing, because the electrical current tries to find the shortest path to the workpiece.

Things to Remember

Place your noncutting hand down and use it as a guide for the other hand. Keep the torch perpendicular to the metal that is being worked on. Touching the tip to the work surface or moving it too far can adversely affect cut quality and consumable life.

  • April 3, 2017
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