A well-maintained plasma cutting system operated by an experienced operator can save a fabrication unit several hours of downtime, not to mention hundreds of pounds in operating expenses. However, here are some common mistakes that should be avoided:
Overusing consumables, especially if they are worn out can ruin the workpiece you are cutting, plasma torch failure and wasteful downtime. Here are some signs of worn consumables i.e. colour and sound of the arc or any small change in the torch height shows that the parts are worn. Check the quality of the cut edge regularly and if the cut quality starts deteriorating, check the torch parts. Maintain a record of the average consumable life and when this is established, you will know when the parts must be changed to prevent complete failure of the torch.
Using the Wrong Parts
Depending on the material and its thickness, the plasma gas used, the amperage and other cutting restrictions, the consumables must be selected. You can check the operator manual that will specify the consumables required for different types of cutting. Using the wrong consumables can lead to reduced cut quality and shorter part life. The parts must also be run at the correct amperage. If the amperage is too low, you will get inferior cuts and the nozzle life will suffer if the amperage is too high.
Incorrect Torch Assembly
All the parts of the plasma torch should be assembled correctly and snugly, which ensures proper electrical contact and flow of coolant and gas through the plasma torch. The consumables should be kept clean to prevent the metal dust or dirt contaminating the plasma torch. Avoid using excess of lubricant on the O-rings, as it can result in clogging of the swirl ring and also contaminate the torch, which will result in an uncontrolled arc leading to the failure of the torch. Avoid applying grease to the torch at all cost.
With proper maintenance and care, plasma torches can last for several years. All parts should be kept clean and checked for any damage.
Checking the Coolant and Gas Flow
The pressure and flow of the coolant and gas must be checked daily and if the flow is not adequate, the consumable life will be reduced as they will not be cooled properly. This can also lead to plasma torch failure. To maintain the cutting arc, constant gas pressure is required. If the pressure is too high, it will cause hard starting where the arc initiation fails and also causes deterioration of the electrodes. The plasma gas must be kept clean of moisture, oil and particulate matter to prevent short torch and consumable life.
There are other mistakes that you must avoid when cutting with a plasma torch such as cutting too slow or very fast, piercing very low, stretching the plasma arc and crashing the plasma torch. Regular maintenance of the torch consumables and the plasma torch itself is very critical for the plasma cutter to work at its highest efficiency and produce high-quality, accurate cuts.