CNC plasma cutter is currently a popular cutting method in the market. Together with the CNC flame cutter, it occupies half of the international cutting equipment market share. And the current fine CNC plasma cutter is no less than a laser cutter in terms of cutting speed and cutting quality. Today, Huafei CNC will give users a detailed introduction to the evaluation criteria of CNC plasma cutter cutting quality. The evaluation standard of cutting quality mainly consists of five aspects: the width of the cut, the surface roughness, the squareness of the edge of the cut, the width of the heat-affected zone, and the amount of slag. The specific requirements are as follows:
(1) Incision width.
It is one of the most important characteristics to evaluate the cutting quality of the cutting machine, and it also reflects the radius size of the smallest circle that the cutting machine can cut. It is measured by the size of the widest part of the incision. Most plasma cutters have an incision width of 0.15 to 6.0mm. The impact:
a. The excessively wide incision will not only waste material but also reduce cutting speed and increase energy consumption;
b. The width of the notch is mainly related to the nozzle aperture. Generally, the width of the notch is always 10% to 40% larger than the nozzle aperture;
c. When the cutting thickness increases, it is often necessary to use a larger nozzle aperture, and the cut will also be widened;
d. Increasing the width of the cut will increase the deformation of the cut piece.
(2) Surface roughness.
It is used to describe the appearance of the incision surface, to determine whether reprocessing is required after cutting, and to measure the Ra value on the cross-section at 2/3 of the incision depth. As a result of the longitudinal vibration in the cutting direction due to the cutting airflow, cutting waves are mainly formed. Generally, the surface roughness after oxyacetylene cutting is required: Level 1 Ra≤30μm, Level 2 Ra≤50μm, Level 3 Ra≤100μm. The Ra value of plasma arc cutting usually exceeds the level of flame cutting but is lower than the Ra value of laser cutting (less than 50μm).
(3) The squareness of the cutting edge.
It is also an important parameter reflecting the cutting quality, and it is related to the degree of reprocessing required after cutting. This index is usually expressed by perpendicularity U or angle tolerance. Generally, the U value of plasma arc cutting is closely related to the plate thickness and process parameters, usually U≤(1%～4%)δ (δ is the plate thickness).
(4) The width of the heat-affected zone.
This index is very important for those low alloy steels or alloy steels that can be hardened or heat treated. Excessively wide heat affected zone width will significantly change the performance near the incision. The width of the heat-affected zone of air plasma arc cutting is about 0.3mm, and the width of the heat-affected zone can be narrower when cutting underwater plasma.
(5) The number of dregs.
It describes how much oxide slag or resolidified material adheres to the lower edge of the cut after thermal cutting. The level of dross is usually determined by visual observation and is generally described as no, slight, moderate, and severe. Also, there should be corresponding requirements for the straightness of the slit, the melting of the upper edge, and the gap.
Since cutting quality is very important for CNC plasma cutter, what are the requirements for CNC plasma cutter to improve cutting quality?
(1) The functional components of the CNC plasma cutter must be closely integrated. The gap between the bearing and the pinhole should not be too large, because the cutting process is carried out at the same time when the casting blank is moving, and the looseness of each part will cause the swing of the cutting gun, which will affect the cutting effect.
(2) The swing of the cutting gun in the cutting machine and the inclined plate of the positioning control part should not be too short.
(3) The position of the cutting torch must be fixed, the height is reasonable and vertical, and there must be no deviation in front, back, left, and right.
(4) The choice of the plasma power supply must match the thickness of the cutting material, otherwise, it will directly affect the cutting quality of the CNC plasma cutter.