Wide Application of Stainless Steel Thick Plate Workpieces
With the continuous development of laser cutting technology, 10,000-watt models in the market to increase the utilization rate, stainless steel plate applications are also increasingly broad. At present, stainless steel thick plate products have been widely used in shipbuilding, bridge engineering, machinery manufacturing and construction engineering and other industries. In terms of the current process standards, the best way to cut stainless steel plate is to use high-power laser cutting machine to complete.
Laser Cutting Stainless Steel Thick Plate Process Requirements
Generally speaking, the medium plate is a steel plate with a thickness of 10.0-25.0mm, the thickness of 25.0-60.0mm is called thick plate, and the thickness of more than 60.0mm is extra thick plate. In the actual cutting, to measure the merits and demerits of thick plate cutting, mainly from the roughness, verticality, cutting width, grain, burr, the size of the heat-affected area, and whether or not to cause plate deformation in the cutting and so on several aspects of a comprehensive judgment. Specifically, you want to cut a high-quality stainless steel thick plate workpiece, you need to pay attention to the following points in the process.
The size of the nozzle diameter determines the shape of the gas flow into the kerf, the gas diffusion area, the gas flow rate, which affects the removal of molten material, the stability of the cut. Entering the mouth of the gas flow is large, fast, the workpiece in the gas flow in the appropriate position, the stronger the ability to remove the melt jet. The thicker the stainless steel, the larger the nozzle should be used, and the larger the proportional valve is set to increase the flow rate in order to ensure that the pressure is sufficient to cut a normal section effect.
The specification of the nozzle here mainly refers to the end of the aperture, Precitec's cutting nozzle, for example, its aperture from 1.5mm to 5.0mm. the selection of the aperture is mainly related to the cutting power, the higher the power, the more heat generated, the greater the need for air volume. When we cut the plate below 3mm, generally choose 2.0mm aperture nozzle; cut 3mm to 10mm plate, choose 3.0mm nozzle, cut more than 10mm plate, we need to use 3.5 and above the nozzle. Single and double nozzles: Generally speaking, oxidation cutting (auxiliary gas is oxygen) with double nozzles, fusion cutting (auxiliary gas is nitrogen) with single nozzles. However, some lasers have special instructions on whether to use single or double layer, in which case, operate according to the laser instructions.
Auxiliary gas selection and gas purity
Stainless steel laser cutting process often use a variety of auxiliary gases, such as oxygen, nitrogen, air, etc., the use of different types of gases, the effect of cutting section is different. Oxygen is black section, a little for cutting speed is high, can cut thick plate material, purity is recommended ≥ 99.999%; air is light yellow; nitrogen can keep the original colour of stainless steel is not oxidized, the workpiece so do not need to re-processing, purity is recommended ≥ 99.995%. Stainless steel cutting with nitrogen as the preferred auxiliary gas.
Focus is not the same, the thickness, material and quality that can be cut is not the same, cutting different materials and thicknesses, all need to be adjusted to a different focus. Before cutting, measure the actual zero focus, to zero focus as a benchmark to be able to test and analyse the cutting process parameters, stainless steel cutting to negative defocus as the main direction of process selection.
Laser frequency adjustment on the impact of cutting
Frequency changes on the impact of stainless steel thick plate cutting: frequency from 500-100Hz range decreases, the cutting section effect becomes delicate, delamination slowly improve. When the frequency is set to 100Hz, it is impossible to cut and anti-blue light. Find out the optimum frequency range by changing the frequency. In order to ensure the best cutting section, it is necessary to ensure that the number of pulses is perfectly matched with the single pulse energy. Pulse duty cycle changes on the impact of stainless steel thick plate cutting: pulse duty cycle 45% is the critical value, continue to reduce the duty cycle, the lower surface of the appearance of uncut traces, the duty cycle increased to 60%, the section becomes rough, delamination is obvious, yellowing of the cutting surface.