There are five important factors that influence the precision of plasma cuts, let us start learning the factors to get better plasma cuts with your plasma cutter, including working gas, cutting speed, cutting current, nozzle height, and arc power.
1. Working Gas
The working gas and flow rate are the main parameter that affects the cutting quality. At present, the general use of air plasma cutting is only one of many working gases. It is widely used because of the relatively low cost of use. The effect is indeed lacking. The working gas includes gas and auxiliary gas. Some equipment also requires arc starting gas. Usually, the appropriate work is selected according to the type of cutting material, thickness and cutting method. gas. The gas must not only ensure the formation of the plasma jet, but also ensure that the molten metal and oxide in the cut are removed. Excessive gas flow will take away more arc heat, making the length of the jet shorter, resulting in reduced cutting capacity and arc instability; too small gas flow will cause the plasma arc to lose its straightness and cut. The depth becomes shallower, and it is also easy to produce slag; therefore, the gas flow must be well matched with the cutting current and speed. Current plasma arc cutting machines mostly rely on gas pressure to control the flow rate, because when the torch aperture is fixed, the gas pressure also controls the flow rate. The gas pressure used to cut a certain thickness of material is usually selected according to the data provided by the customer. If there are other special applications, the gas pressure needs to be determined by the actual cutting test.
2. Plasma Cutting Speed
In addition to the influence of working gas on cutting quality, the effect of cutting speed on the processing quality of CNC plasma cutting machine is also very important. Cutting speed: The optimal cutting speed range can be selected according to the equipment description or determined by experiment. Due to the thickness of the material, the different materials, the melting point, the thermal conductivity and the surface tension after melting, the cutting speed is also corresponding. Variety. main performance:A. A moderate increase in cutting speed can improve the quality of the cut, that is, the cut is slightly narrower, the cut surface is smoother, and deformation can be reduced.B. The cutting speed is too fast so that the linear energy of the cutting is lower than the required value. The jet in the slit cannot quickly blow away the molten cutting melt immediately to form a large amount of trailing drag. decline.C. When the cutting speed is too low, because the cutting place is the anode of the plasma arc, in order to maintain the stability of the arc itself, the CNC spot must inevitably find the conduction current near the slit nearest the arc, and will The radial direction of the jet transfers more heat, so that the incision is widened. The molten material on both sides of the incision gathers and solidifies at the bottom edge, forming a slag that is not easy to clean, and the upper edge of the incision is heated and melted to form a rounded corner.D. When the speed is extremely low, the arc will even extinguish due to the incision being too wide. This shows that good cutting quality and cutting speed are inseparable.
3. Plasma Cutting Current
The cutting current is an important cutting process parameter, which directly determines the thickness and speed of the cutting, that is, the cutting ability, which affects the correct use of plasma cutting machine for high-quality rapid cutting, the cutting process parameters must be deeply understood and mastered.
4. Nozzle Height
Nozzle height refers to the distance between the nozzle end face and the cutting surface, which constitutes a part of the entire arc length. Plasma arc cutting generally uses a constant current or steep drop external power supply. After the nozzle height is increased, the current changes little, but it will increase the arc length and cause the arc voltage to increase, thereby increasing the arc power; but at the same time As the arc length exposed to the environment grows, the energy lost by the arc column increases.In the case of the combined effect of the two factors, the former’s role is often completely cancelled by the latter, but the effective cutting energy will be reduced, resulting in a reduction in cutting capacity. It usually shows that the blowing force of the cutting jet is weakened, the residual slag at the lower part of the incision is increased, and the upper edge is over-melted to produce rounded corners. In addition, considering the shape of the plasma jet, the diameter of the jet expands outwards after leaving the torch mouth, and an increase in the height of the nozzle inevitably causes an increase in the width of the cut. Therefore, it is beneficial to improve the cutting speed and cutting quality by selecting the nozzle height as small as possible. However, when the nozzle height is too low, it may cause double arc phenomenon. Using the ceramic outer nozzle can set the nozzle height to zero, that is, the end face of the nozzle directly contacts the surface to be cut, and a good effect can be obtained.