Abstract: Some standards can help evaluate the cutting quality of plasma cutter table, take those standard into consideration when applying cnc plasma table for sheet-metal fabrication to improve the working efficiency & cutting performance.
CNC plasma cutter table machine, owing to its excellent performance and competitive price, is widely used in different kinds of metal fabrication industries. However, no national standard is available, which can help evaluate the cutting quality of cnc plasma table. Actually some factors need to be taken into consideration as follow:
1. The width of the incision:
It is one of the most important characteristic values to evaluate the cutting quality of the metal cutting machine, and it also reflects the radius 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 cutting machines have an incision width between 0.15 and 6 mm.
1).Excessively wide incisions will not only waste materials, but also reduce cutting speed and increase energy consumption.
2).The slit width is mainly related to the nozzle aperture. Generally speaking, the slit width is always 10%-40% larger than the nozzle aperture.
3).When the cutting thickness increases, it is often necessary to use a larger nozzle aperture, and the cut will also be wider.
4).Increasing the width of the cut will increase the deformation of the cut piece.
Used to describe the appearance of the cut surface and determine whether it needs to be processed after cutting. It is the Ra value on the cross section at 2/3 of the depth of the cut. As a result of longitudinal vibration in the cutting direction due to the action of the cutting airflow, the main form is cutting ripples. Generally, the surface roughness after oxyacetylene cutting is required: Level 1 Ra≤30 microm, Level 2 Ra≤50 microm, Level 1 Ra≤100 microm, The Ra value of plasma arc cutting is usually higher than that of flame cutting, but lower than the Ra value of laser cutting (less than 50 microm)
3. Squareness of the edge of the incision:
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 speaking, the U value of plasma arc cutting is closely related to plate thickness and process parameters, usually U≤(1%~4%)δ (δ is plate thickness), and laser cutting U≤0.5mm.
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 for air plasma arc cutting is about 0.3mm, and the width of the heat-affected zone for underwater plasma arc cutting can be even narrower.
5. Amount of slag hanging:
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 in terms of no, slight, moderate and severe.
In addition, there should be corresponding requirements for the straightness of the slit, the melting of the upper edge and the gap.