What is the Correct operation of CNC plasma cutting machine

The selection of cutting process parameters for CNC plasma cutting machine has a crucial impact on cutting quality, cutting speed and efficiency. To correctly use a CNC plasma cutting machine for high-quality, 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 cutting, that is, cutting capacity. The larger the cutting current, the higher the cutting capacity, the higher the cutting speed, the wider the cutting opening, the faster the damage speed of the cutting nozzle, and the higher the cost. Therefore, the cutting current must be correctly selected according to the thickness of the material before cutting.

2. Cutting speed

The optimal cutting speed range can be selected according to the equipment instructions or determined by experiments. Due to the thickness of the material, different materials, melting point, thermal conductivity, surface tension after melting and other factors, the cutting speed will also change accordingly. The speed directly affects the cutting quality, higher and lower are not good.

3. Arc voltage

It is generally believed that the normal output voltage of the power supply is the cutting voltage. CNC plasma cutting machines usually have higher no-load voltage and working voltage. When thea current is constant, an increase in voltage means an increase in arc enthalpy and 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, faster cutting speed and better cutting quality can often be obtained.

4. Nozzle height

Refers to the distance between the nozzle end face and the cutting surface, which forms part of the entire arc length. Since CNC plasma cutting machine generally use power supplies with constant current or steep drop characteristics for arc cutting, when the nozzle height increases, the current changes very little, but it will increase the arc length and increase the arc voltage, 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 loss of the arc column.

In the case of the combined effect of the two factors, the effect of the former is often completely offset by the latter, which will instead reduce the effective cutting energy and reduce the cutting ability. The usual manifestations are that the blowing force of the cutting jet weakens, the residual slag in the lower part of the cut increases, and the upper edge is over-melted resulting in rounded corners, etc.

5. Cutting power density

In order to obtain a highly compressible plasma arc cutting arc, the cutting nozzles adopt a smaller nozzle aperture, a longer channel length and an enhanced cooling effect. This 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% and 50%. Some methods such as water compression plasma arc cutting The energy loss rate will be greater. This issue should be considered when designing cutting process parameters or economic calculation of cutting costs for CNC plasma cutting machines.

Increasing the compression of the arc stretches the high-temperature plasma jet, creating a more uniform high-temperature zone. At the same time, increasing the injection speed can reduce the width difference between the upper and lower sides of the incision. However, excessive compression of conventional nozzles often results in double arcs. The double arc will not only wear the electrodes and nozzles of the CNC plasma cutting machine, making the cutting process impossible, but also cause the cutting quality to decrease. In addition, excessive cutting speed and excessive nozzle height will lead to an increase in the upper and lower width difference of the incision.