Routine maintenance of a plasma cutter machine is crucial for retaining a well-functioning arc starting circuit and sustaining optimal system performance. Consumables are primarily responsible for most common plasma cutter troubles. Here we shall discuss the solutions to some common technical difficulties of a plasma cutter to help keep your plasma cutter running as efficiently as possible.
Q: Plasma torch fails to spark or incorrect arc initiation
Electrode wearing- A plasma torch may fail to spark or only sporadically arc due to malfunctioning or damaged parts. Check if the copper electrode has turned black or blue and the crater at the tip has widened. A low coolant flow may be the cause. See instructions manuals for recommended flow rate and set the machine flow rate accordingly. Ensure that the line is free of twists and leaks that prevent free flow. It is a must to replace a fully melted electrode.
Contaminated air- A thick layer of black residue over the electrode will indicate poor gas quality. Contaminated gas may impede the torch's start and working efficiency. Ensure that the water separator in the airline is properly working and not saturated, which will require purging the water out. Ensure that the air is free from any moisture and particles. Set the recommended air pressure both on the compressor and plasma cutter. Any moisture or oil in the air will cause the arc to transfer inside the torch leading to poor part quality and reduced consumable life. A clean and dry air supply will make the cutter last longer.
Nozzle- Check the nozzle interior for any abnormality such as gauge or slot that potentially may create a low gas pressure zone inside the plasma chamber. Fix any leak on the gas line, especially at joints and fittings.
Q: The plasma cutter produces an uneven arc, a blank arc or an arc seeking to blow out the sides of the consumables
Blocked air holes- Thread off the retaining cap. Some plasma cutters have torch caps or retaining caps with air holes inside like shield caps. These types of retaining caps are called external nozzles. Shield gas passes through the air holes. The air holes help cool the torch and keep the arc focused in the right direction. Hold the retaining cap or shield cap up to a light to identify any plugged hole. Plugged holes will cause the torch to overheat and the arc to blow out of the side as it loses direction. Also, blocked holes may deform the arc bottom leading to imprecise cut. If there are clogged holes, replace the cap. Cross-check the air holes regularly during long cutting and before starting a new cutting session. Usually, these consumables serve the longest.
Electrode- Plasma cutter electrodes can either be a thread type or slide type. A loosely installed electrode can cause the arc to be unsteady. Electrodes are the second-fastest wear-out consumables.
Also read: How to Optimize Plasma Cutter Performance?
Q: Cut quality problems such as having excess slag or larger than standard cuts
Damaged cutting tip or nozzle- The plasma arc exits through the cutting tip that performs the cutting job. This cutting tip is also known as a nozzle. Since a cutting tip performs the actual cutting action, it is the quickest wear-out consumable. A larger and irregularly shaped central hole will indicate an excessively worn nozzle allowing the arc to drift. As the nozzle orifice enlarges, its cutting precision will decline. So, an enlarged central hole will produce excessive dross accumulation on the backside of the cut piece and an abnormally high degree of bevel angle. Also, an expanded orifice will not help cut the same thickness at a given amperage because the arc will stretch out and lose intensity. However, the color of the cutting tip has no impact on the cut quality. A deformed cutting tip needs to replace.
Q: Troubleshooting poor air quality problems
Poor quality air will cause plasma cutter consumables such as cutting tips and electrodes to wear out rapidly. Generally, plasma cutter machines run on air from an air compressor or bottled air. A bad-quality air is likely to contain moisture and oil alongside metal and rust particles originating from the bottom of the air compressor tank, gas bottle, and air carrier lines. All this stuff is electrically conductive. When these substances travel through an energized plasma torch, they interact with high voltage forcing the torch consumables to wear out fast. Installing appropriate filters/dryers on the line will prevent these things from entering the plasma cutter, removing their impact on consumables and the cut. Many companies manufacture specialized filters for various impurities such as moisture, oils, different-sized particles, etc. Both inline filters and built-in moisture separators need to examine regularly for purging out and possible degradation.
A properly run plasma cutter machine will save money and valuable time. Proper operation will ensure a longer life for consumables and the system, minimizing operating costs. Also, a lesser need for repair saves expenses and time. In the end, a clean and high-quality cut saves the time and labor needed to clean a badly cut metal.