Plasma Cutting – How To Get The Perfect Cut?

The art of cutting the conductive materials with an extremely hot jet of plasma is known as plasma cutting. This process has a widespread usage in fabrication industries, welding and automotive shops and steel restoration factories. There are people who choose to do it as a hobby. Plasma cutting is popular among hobbyists, small entrepreneurs who believe in doing things themselves and larger industries. There is a learning curve for beginners and following some practices will help in improving the quality and precision of the cuts, quality of the overall process and also help in maintaining the equipment in good health.

How to set up a plasma cutter

  • Before you set up the plasma cutter, it is important to go through the owner’s manual to get enough exposure to the cutter and its parts. Also familiarize with the operation and various tactics to ensure the process is smooth.
  • Hooking up the plasma cutting unit to compressor air knob is the first process in setting up a plasma cutter. The air supply is different for various cutters. It is important to know about the built-in regulator which comes with every cutter. This regulator and its position determine and regulate the air flow for the process.
  • Setting up the amperage is another step. The heat or amp determines the quality of cut most of the times. Also, the heat and the travel speed of the arc should be ideal or the cut gets deep or there is dross accumulation over the metal which we don’t want. Here we recommend a practice session before you work on the actual product. Choose a metal similar to the one you will be working on, practice certain cuts choosing optimum amperage and travel speed. A point to remember is amperage can be set at high and then slowly brought to minimum depending on the travel speed.

A plasma cutter can be used for various types of metals and the process needs to be different like cutting, gouging and piercing.

Plasma arc cutting

Image Soure: http://www.designinsite.dk/

Image Soure: http://www.designinsite.dk/

Choose a base metal which needs to be cut and place the plasma torch tip close to the sheet of metal.  Switch on the trigger to start the air supply. The pilot arc and cutting arc are ignited once the pre flow of airflow sets in. Once the cutting arc is initiated, start moving the torch slowly and steadily across the metal. The sparks should ideally burst out of the bottom of the metal, if not speed must be adjusted.  If there are no sparks at the bottom, it simply means less penetration of arc. This less or no penetration results in bad performance. It could be due to the following reasons and need corrections –

  • High Travel speed
  • High or low level amperage
  • The angle making the cut needs a change in direction

Post the process, a brief pause at the end of the metal to steady the angle and switch off the trigger. The airflow still progresses for a while to cool the parts and torch. Cutting process could be resumed by switching on the trigger again.

Plasma Arc Gouging

Gouging a metal basically depends on the angle of handling. When the torch is operated over the base metal at an angle of 40 degrees, it is called gouging. The trigger has to be switched on for the air flow and pilot arc followed by the cutting arc. Post ignition of the cutting arc, an arc length needs to be accomplished with a slow and steady travel speed. Gouging deep might not result in success.  A perfect gouge results after a number of passes.

Plasma arc piercing

Piercing is successfully creating a perfect hole on the metal base. Switch on the trigger after placing the torch at 40 degrees to the metal base. Once the air flow initiates followed by pilot arc and cutting arc, move the torch to 90 degrees against the metal and start piercing sharp holes. The thickness provided by the machine is deep and if half the thickness is penetrated, it is a job well done.

Cutting techniques that come in handy

Long Cuts

  • A long cut is difficult to achieve for beginners. A clean cut is what one can begin with. Practice on a similar metal will come in handy. Efficient hand movements along with a balanced speed help in producing the desired cut.
  • Using the other hand to hold the metal and comfortably placing it helps in holding the torch steadily.
  • Frequent pauses on the metal will result in residue and dress accumulation.

Thick and thin materials

  • The machine needs to be set to full speed and the travel speed must be adjusted accordingly while cutting through a thicker material.
  • On thinner materials, narrow kerfs could be maintained easily by turning the amperage down. A lower amperage tip helps in maintaining a steady arc.
  • While at work, when the arc sprays off bursting, it typically means the travel speed is pretty high. When the arc moves steadily and goes straight down, it typically means the movement speed is slow.
  • A template created for straight, circular and other types of cuts come in handy. If there is a drag shield along with the plasma cutter, it could be effectively used to rest the torch 0oon the metal piece while providing an optimal standoff of 1/8 inches.

Safety Procedures

The most vital thing while using a plasma cutter is safety. The safety manual and instructions create awareness among the workers. Basic safety measures like –

  • Welding gear and clothes
  • Protection to eyes
  • Gloves and shoes

This process involves very hot fumes, ultra violet rays, electricity and molten metal. Every precaution to keep oneself protected is essential. Certain examinations like looking up the electrode tip, inspecting the space of shield and the metal piece that needs work will make the procedure easy. The consumption life of the device could be increased by following the safety tips and owner’s manual.

  • Updated October 2, 2016