In the 2nd part of the article on “Cooling Systems for Plasma Cutting Machines”, we will look at other components that comprise the cooling system in a plasma torch, their functions and some common problems faced with these parts.
The hoses that carry coolant to and from the torch are known as cooling lines, which also contain the main power cables. The heating of the copper wires is prevented by the water-cooled power cables. In the case of automated cutting applications, the cooling lines are hung over the cutting system or routed through the power track.
Common Cooling Line Problems
Sometimes the cooling lines may be cut, cracked or melted which can cause the cooling fluid to leak into unseen areas e.g. just above the plasma torch within the mounting tube.
Sometimes debris may accumulate causing a blockage and restrict the flow of the return leads. Also, the constant flexing of the copper power cables may cause the copper filaments to break and clog the hoses. These kinds of blocks can result in reduced flow and cause the wearing of the motor and the pump.
This usually helps to prevent the failure of the plasma torch and the parts in case the coolant flow gets too low.
Common Flow Switch Problems
The flow of the coolant activates the mechanical plunger. This plunger may get stuck in the open or closed position and can cause a fault condition when the flow of the coolant becomes very low. The plunger can be removed and cleaned; however, in the case of a failure, it is best to replace it.
The electrical switch may fail if the contacts are worn out. However, this is not a common occurrence.
Many times, flow switches are “jumpered out” of the system and this is very dangerous as the flow switch is a very important safety component that prevents the torch from failing because of overheating.
Particulate filters are used by many cutting systems to remove any debris or contaminants from the plasma torch coolant. These filters usually comprise a 5 microfilter paper or use a de-ionizing filter. The filter must be changed whenever the flow in the cutting system reduces or it is a good practise to change it every few months.
Common Flow Filter Problems
Common problems include contaminated filter, wrong filter or no filter.
Usually, for plasma cooling systems, the heat exchangers consist of a fan and a radiator. The airflow is directed by the fans through the radiator and removes the heat from the coolant. Some cutting systems are equipped with refrigerated chillers to cool the coolant.
Common Heat Exchanger Problems
The fans must be checked regularly to ensure that they are working properly, otherwise, the fan motor can get burnt out. You must clean the cooling fins and radiator regularly as dirt build-up can cause the cooling efficiency to be reduced.
This is a metal or a plastic tank that usually holds the torch coolant. Usually, float switches, temperature switches and level indicators are installed inside the tank to prevent overheating. You should check the coolant reservoir every day and top it up as required to ensure that there is adequate coolant in the reservoir always.
If the level of coolant is too low, air will get into the coolant stream and the cooling effect will be reduced. The low coolant level can cause the system to intermittently or completely shut down if the system is interlocked and if it is not interlocked, the air can cause the pump to get overheated and cause failure.
Common Coolant Reservoir Problems
Debris may collect at the bottom of the tank, which must be removed or flushed out. The tank must also be removed periodically and steam cleaned. Inadequate levels of coolant may also cause problems and the levels must be checked regularly.
Thus, for your plasma cutting system to function efficiently, the torch and the consumables must be kept cool otherwise, they may get overheated and wear out prematurely and in the long run, cause complete failure of the plasma torch.