Non ferrous metals generally refer to all metals except iron (sometimes including manganese and chromium) and iron-based alloys. Aluminum and its alloys are also non-ferrous metals. In the metal processing industry, laser cutting machines are common processing equipment. Fiber laser cutting machines can process aluminum and its alloys.
Laser cutting of aluminum and its alloys:Pure aluminum is more difficult to cut than iron-based metals due to its low melting point, high thermal conductivity, and especially its low absorption rate for CO2 laser. Not only is the cutting speed slow, but the lower edge of the cut is prone to sticking slag and the cutting surface is rough. Due to the presence of other alloying elements in aluminum alloy, the absorption rate of CO2 and laser increases in solid state, making it easier to cut than pure aluminum. The cutting thickness and cutting speed are also slightly higher. At present, the cutting of aluminum and its alloys is usually carried out using CO2 laser, continuous laser, or pulsed laser.
CO2 gas continuous laser cutting:
(1) Laser power.
The laser power required for cutting aluminum and its alloys is greater than that required for cutting iron alloys. A laser with a power of 1 kW can cut industrial pure aluminum with a maximum thickness of about 2 millimeters, as well as aluminum alloy plates with a maximum thickness of about 3 millimeters. A laser with a power of 3kW can cut industrial pure aluminum with a maximum thickness of about 10mm. The laser has a power of 5.7kw and can cut industrial pure aluminum. The maximum thickness is about 12.7mm, and the cutting speed can reach 80cm/min.
(2) The type and pressure of auxiliary gas.
The type and pressure of auxiliary gas have a significant impact on cutting speed, adhesion of cutting slag, and roughness of cutting surface when cutting aluminum and its alloys.
Using O2 as an auxiliary gas, the cutting process is accompanied by an exothermic oxidation reaction, which is beneficial for improving the cutting speed.
Using N2 as an auxiliary gas, since N2 does not react with the base metal during the cutting process, the drillability of the slag is not very good. Even if it is hung at the bottom of the cut, it is easy to remove.
When cutting aluminum alloys for aviation, dual auxiliary airflow is also used. The inner nozzle sprays nitrogen gas and the outer nozzle sprays oxygen flow, with a gas pressure of 0.8M pa, to obtain a cutting surface with no viscous residue.
(3) Cutting process and parameters.
The main technical problem of CO2 continuous laser cutting of aluminum and aluminum alloys is to eliminate slag inclusion and improve cutting surface roughness. In addition to selecting appropriate auxiliary gas and cutting speed, the following measures can also be taken to prevent slagging.
Pre coat a layer of graphite based anti sticking slag agent on the back of the aluminum plate.
The film used for aluminum alloy plate packaging can also prevent slag sticking.