The correct use of CNC plasma cutting machine to help you get started quickly
August 31, 2021
The choice of cutting process parameters for CNC plasma cutting machine is of vital importance to cutting quality, cutting speed and efficiency. If you want to use the CNC plasma cutting machine for high-quality and fast cutting, you must have a deep understanding and mastery of the cutting process parameters.
1. Cutting current
It is the most important cutting process parameter, which directly determines the thickness and speed of the cutting, that is, the cutting ability. The larger the cutting current, the higher the cutting ability, the cutting speed, the width of the cutting opening, the faster the damage speed of the cutting nozzle, and the increase in cost. Therefore, the cutting current should be correctly selected according to the thickness of the material before cutting.
2. Cutting speed
The best cutting speed range can be selected according to the equipment description or determined by experiments. Due to the thickness of the material, different materials, high or low melting point, thermal conductivity, and surface tension after melting, the cutting speed also changes accordingly. The speed directly affects the cutting quality, and higher and lower speeds are not good.
3. Arc voltage
It is generally considered that the normal output voltage of the power supply is the cutting voltage. Plasma cutting machines usually have higher no-load voltage and working voltage. When the current is constant, the increase of the voltage means the increase of the arc enthalpy and the increase of the cutting ability. If the diameter of the jet is reduced and the flow rate of the gas is increased while the enthalpy value is increased, a faster cutting speed and better cutting quality can often be obtained.
4. the nozzle height
Refers to the distance between the nozzle end face and the cutting surface, which constitutes a part of the entire arc length. Since the arc cutting of CNC plasma cutting machine generally uses a power supply with constant current or steep drop characteristics, after the nozzle height increases, the current change is small, but the arc length will increase and the arc voltage will increase, thereby increasing the arc power; but at the same time It will also increase the arc length exposed to the environment and increase the energy lost by the arc column.
In the case of the combined effect of the two factors, the role of the former is often completely offset by the latter, which will reduce the effective cutting energy and reduce the cutting ability. The usual performance is that the blowing force of the cutting jet is weakened, the residual slag in the lower part of the incision increases, and the upper edge is overmelted and rounded.
5. Cutting power density
In order to obtain a highly compressible plasma arc cutting arc, the cutting nozzle adopts a smaller nozzle aperture, longer channel length and enhanced cooling effect, which can increase the current passing through the effective section of the nozzle, that is, the power density of the arc Increase. But at the same time compression also increases the power loss of the arc. Therefore, the effective energy actually used for cutting is smaller than the power output by the power supply. The loss rate is generally between 25%-50%. Some methods such as water compression plasma arc cutting The energy loss rate will be greater. This issue should be considered when the CNC plasma cutting machine is designed for cutting process parameters or economic calculation of cutting costs.
Increasing the degree of compression of the arc can extend the high-temperature plasma jet to form a more uniform high-temperature area. At the same time, increasing the jet velocity can reduce the width difference between the upper and lower cuts. However, the excessive compression of conventional nozzles often causes double arcs. The double arcs will not only wear the electrodes and nozzles, make the cutting process impossible, but also cause the quality of the cut to decrease. In addition, excessive cutting speed and excessive nozzle height will cause an increase in the difference between the upper and lower width of the cut.