Any cutting process requires the use of consumables. Plasma cutting is no exception. Timely replacement of consumables guarantees the preservation of the quality of the materials produced, eliminates defects, and also plays an important role in the long-term operation of the equipment.
It is best to purchase original consumables for plasma cutting, since the companies that produce them guarantee high productivity of the work process, excellent reliability and extended service life of the equipment.
It is the original consumables for plasma that can provide consistently high quality cuts. Such materials are produced by the company HYPERTHERM, whose products have good characteristics at an affordable price.
Types of consumables for plasma cutting
An electrode (aka cathode) is a part of a plasmatron, made of a refractory metal and having inserts made of tungsten, hafnium or zirconium. Depending on what equipment it is required for, different parts are selected.
An important role is played by the nozzle, which forms a plasma jet of the desired shape. It can be a contact element if the device does not have high-frequency ignition. It is usually made of copper or steel, and its design also depends on the type of specific machine.
Due to the nature of its function, the nozzle is considered one of the fastest wearing elements. To protect the main components of the plasma torch from dust and hot metal particles, a ceramic nozzle is used - a special protective cap made of thermoplastic.
The diffuser or swirler, as it is also called, is also a necessary element that provides an increase in pressure and expansion, that is, a slowdown in flow during operation.
A hand torch is a device that generates plasma during the cutting process. It connects to a power source and provides high-quality metal processing. The main components of the device are the electrode and its holder, nozzle, arc chamber, insulator (separating the electrode and nozzle units), as well as gas and water supply systems. It is also possible that there is a vortex node.
The guard makes it easier to move the torch and allows for smooth, consistent cuts. And for cutting without it, a deflector is used. Special casings for plasma cutting are also purchased. They operate over fairly large cutting thickness ranges and, depending on the system used, provide different operating speeds.
Causes of premature electrode wear
There are several reasons, let's look at each briefly. Also, as you read the article, we will suggest where to buy electrodes at the lowest prices in your city or region.
The air has impurities
The air supplied by the compressor must be free of oil and moisture. The filter with moisture separator must be checked every day.
Low quality plasma gas
The choice of plasma-forming gas depends on the set of consumables. It is very important to use gas strictly in accordance with the “Operation Manual”. For example, when working with inert gases (a mixture of argon with hydrogen and nitrogen), oxygen or even air should not be allowed to enter this environment. This will lead to premature combustion of the tungsten insert.
Insufficient gas pressure
The gas pressure specified in the Operating Manual should be maintained.
Low pressure and, as a result, a decrease in gas flow leads to the following consequences:
- the electrode burns out;
- sparking occurs;
- the result is a low quality cut;
- The power of the power supply drops.
Interesting: Selecting and replacing a nozzle for plasma cutting
Increased pressure sharply reduces the service life of the electrode (the power does not change).
There is not enough coolant in the plasmatron
In plasma torches, for cooling, a coolant (coolant) circulates between the anode and cathode: deionized water or a mixture of deionized water and pure ethylene glycol. Most models are equipped with a low pressure and flow fuse for this fluid. It prevents overheating of the plasma torch in the event of a malfunction of the cooling system or low coolant consumption, so it is necessary to monitor its serviceability.
If the service life of the electrode becomes shorter than usual, check the coolant flow rate.
Dirty gas pipelines
Even after short-term downtime, gas pipelines need to be cleaned. If the device is operated in conditions of high humidity, then pre-cleaning will not be enough and a complete cleaning should be carried out immediately. Moisture from the gas pipeline can settle on a poorly cleaned electrode and damage it.
The swirler is faulty
The swirler may have various malfunctions:
- burst;
- the circuit is damaged;
- melted.
Even if it is simply clogged with dirt, then in this case the amount of air consumed and even the direction of its movement changes. All this will quickly lead to failure of the electrode. Urgent replacement of the swirler is required.
If the electrodes are changed in a timely manner, the plasma torch will delight its owner for a long time.
Selection options
You need to choose the right type of consumables, taking into account their capabilities, so that they serve long and reliably. Rational use of consumables is possible if their capabilities are taken into account. So, for example, the nozzle and electrode can withstand different numbers of penetrations depending on the following three factors:
- metal type;
- sheet thickness;
- current value.
The type of metal, especially non-ferrous (or alloy), plays a very important role, as it affects the type of consumables required. Stainless or carbon steel, as well as aluminum, can be cut. And for cutting stainless steel at an angle, another separate category of consumables is used. There is also a plasma torch hose package and a whole list of spare parts for it, which include cutter kits, lubricant, couplings and more.
Schemes of a plasma cutter using the example of the APR-91 device
When considering the electrical circuit diagram, we will use the APR-91 plasma cutting machine as a donor.
Power section diagram (click to enlarge)
Plasma cutter control circuit (click to enlarge)
Oscillator circuit (click to enlarge)
How to determine the wear of consumables?
Timely replacement of consumables helps prevent defects when cutting parts, and is also an important measure to prevent problems. Worn elements of the plasma torch can cause its failure and that is why it is so important to be able to determine their condition. There are several points to pay attention to.
1. Color of the plasma arc - over time it becomes greenish.
2. Sound - a characteristic noise occurs during operation.
3. The height of the plasma torch, which decreases during burning.
Of course, in addition to the appearance of all the listed signs, there is another way. This is a determination of the edge quality of parts cut by a plasma torch. Its decline is the best criterion for determining the condition of the torch. If you see the first signs of deterioration in cut quality, then you should pay attention to the condition of the nozzle and electrode.
The easiest way to track the degree of wear of consumables is to have a special journal. With its help, you can record how long on average they work before they become unusable. As a result, it is quite possible to determine the “life” of a particular component. Thanks to such a magazine, it will be possible to plan in advance the replacement of nozzles and other consumables. This is very important, because such an approach will make it possible to avoid breaking the cutter, and the quality of the manufactured parts will always be at its best.
The nozzle should be replaced if its surface is deformed. The cause is molten metal entering due to the small height of the piercing or failure to cut through the metal. If the outlet hole begins to differ in shape or circumference, this is also a signal to replace the material.
To determine whether an electrode is worn, simply look at the silver metal insert on the end of the copper electrode. If the crater depth is less than two mm (or up to 2.2 for argon and nitrogen), then such an electrode is fully operational.
The diffuser requires replacement if cracks, clogged holes, or general wear appear. Swirlers, together with protective caps, are consumables that are generally replaced quite often, even prematurely. However, sometimes you can simply clean them with sandpaper and put them back into use.
Eckert plasma cutting machine SAPPHIRE BL2 in operation:
How to choose a plasma cutter
Before purchasing this device, evaluate the following characteristics:
- Versatility. Some devices are suitable for both metal cutting and stick electrode welding, argon arc welding. However, you need to understand that multifunctionality often has a negative impact on the quality of operations and productivity levels. Universal plasma cutting devices rarely cope with material whose thickness exceeds 11 mm.
- Current strength. With a higher current, the arc heats up more, which means cutting takes less time.
In addition, you can cut parts of greater thickness. Therefore, before purchasing, it is important to understand what you are going to do with this device, what parts to work with. For processing steel no thicker than 20 mm, a device with a current of 20 A is suitable. For thicker sheets, more power is needed - in the range of 40–60 A. For devices used in industry, this parameter is 200 A and higher. - Electrical network type. Household devices even operate on a 220 V network, but you need to be prepared for the fact that the current in them rarely exceeds 40 A. Industrial devices require a 380 V network.
- Duration of switching on (DS). This indicator is set as a percentage and records the time during which the plasma cutter can operate. A working cycle of 10 minutes is taken as a basis. That is, if the PV is 70%, it means that after 7 minutes of operation the device should cool down for 3 minutes. At 40%, the device can work for up to 4 minutes, and then it will need a 6-minute break. You can also find devices with a duty cycle of 100%; they are able to work without stopping, since they use water cooling.
- Compressor. This element of the system can be built-in or separately connected. For home use, devices with a built-in compressor are more convenient. However, they have a drawback - low power. For professional work you will have to purchase a separate compressor. Its task is to provide the plasmatron with constant pressure of dry air. Pulsations are not allowed, and the pressure level must be adjusted to the requirements of the device.
- Convenience. The sufficient length of the cable and hose package is responsible for this property. If the device will be used only at home, it is better to choose a small model to simplify the work.
Price
Due to the strict deflection angle requirements of plasma cutting, it is necessary to increase the kerf width and replace worn parts relatively frequently. However, this applies most of all to the case when gas cooling is used. Only the nozzles and electrodes require frequent regular replacement. If the pipes are changed after five hundred to six hundred cuts, then the electrodes are changed almost twice as often.
A month of work requires a small volume of both types of consumables, which could fit in a small handbag. Since genuine plasma consumables provide better quality at an affordable price, plasma cutting is very economical.
