Overview Of Laser Cutting
1. Principle of laser cutting
Laser cutting uses a high-power and high-density laser beam to irradiate the workpiece to melt, gasify and break it to cut the material, as shown in the figure.
2. Classification of main modes of laser cutting
(1) Gasification cutting uses high-energy and high-density laser beams to heat the workpiece.
So that the surface temperature of the workpiece material quickly rises to the boiling point, part of the material is gasified and disappears, and part of the material is blown away from the bottom of the cutting seam by auxiliary gas and gasified to form a material cut.
Gasification cutting mainly cut fragile metal materials and some non-metallic materials, such as wood, carbon materials, plastics, and rubber.
Thunder Laser Nova series laser cutter mainly uses this cutting method.
(2) Melt cutting
The laser beam with high energy and density can cut heat the workpiece to melt the material, and the nozzle blows high-pressure non-oxidizing gas (such as Ar, He, N, etc.) To discharge the molten material to form a material incision.
Melt cutting is mostly can cut materials that are not easy to oxidize or active metals, such as stainless steel, titanium, aluminum, and their alloys.
(3) Oxidizing, melting, and cutting
A high-energy and high-density laser beam is used as a preheating heat source, and a nozzle blows active gases such as high-pressure oxygen and the like as cutting gases. On the one hand, the high-pressure oxygen reacts with the cut metal to release a large amount of oxidation heat, and on the other hand, the molten oxide and melt are blown out of the reaction zone to form a material cut.
Oxidation melting is mostly used for easily oxidized metal materials such as carbon steel, titanium steel, and heat-treated steel.
(4) Control fracture cutting
A laser beam with high energy and density is used to produce a large thermal gradient and severe mechanical deformation on the brittle material. A minor groove is formed by thermal evaporation. Then a certain external force is applied to make the brittle material fracture along the minor groove to create a material notch.
Controlled fracture cutting can cut the scribing of ceramics and wafers.
Overview Of Laser Cutting Machine System Composition
1. Overall structure of laser cutting machine
According to the relative movement of the laser cutting head and the worktable, the laser cutting machine has three types:
- Fixed beam (fixed optical path)
- Mobile beam (flying optical path)
- Hybrid visual approach (semi-fixed and semi-mobile hybrid)
(1) Beam fixation: During the cutting process, the beam fixation
The cutting head of the cutting machine can not move, and the position of the worktable moves along the X and Y axes, as shown in the figure.
(2) Beam movement: During the cutting process, the beam movement
The cutting head of the cutting machine moves along the X and Y axis directions, and the position of the worktable is fixed, so the processing size is large, and the equipment occupies a small area. The workpiece does not need to be clamped, which is the mainstream cutting machine model.
2. Laser Source for laser cutting machine
(1) CO2 laser
The wavelength of the CO2 laser is 10. 6 μm, which can cut wood, acrylic, PP, plexiglass, and other non-metallic materials and most stainless steel, carbon steel, aluminum, and other metal materials.
Main advantages: As the CO2 laser is continuous, the cutting effect of the section is the best.
Main disadvantages: high price, high maintenance cost, and high operation cost.
Market positioning: 30-130 watt is mainly can cut cutting and engraving non-metallic materials, and 500-20000 watt can cut metal cutting. Thunder Laser currently only does non-metallic laser cutting.
(2) Fiber laser
The wavelength of the fiber laser is 1. 06 μm, which can cut non-metallic materials, and the photoelectric conversion rate is up to 25%.
Main advantages: fine cutting, high degree of flexibility, cutting thickness within 4mm sheet has apparent benefits.
Main disadvantages: high price, difficulty in cutting aluminum plates, copper plates, and other highly reflective materials due to the fine cutting seam and massive gas consumption, and plodding speed when cutting thick plates.
Market positioning: 30-100 watts is mainly for laser marking metal.
High precision cutting of thin plates with less than 12 mm thickness. With the emergence of 5000 W and above power fiber lasers, fiber lasers will eventually replace most high-power CO2 lasers.
(3) YAG solid-state laser
The wavelength of the YAG solid-state laser is 1. 06 μm, which can not cut non-metallic materials, and the output power is generally below 800 W. It can cut drilling and sheet cutting and can have two pulse or continuous action modes.
Main advantages: it can cut aluminum plates, copper plates, and most non-ferrous metal materials, and it has a low price and low use cost.
The main disadvantage is that it can only cut materials with a thickness of less than 8mm, and the cutting efficiency is low.
Market positioning: cutting of metal materials with thickness below 8mm.
3. Laser light guiding and focusing system for laser cutting machine
(1) Function of laser light guide and focusing system:
In the process of laser processing, the laser light guide and focusing system guides and focuses different laser beams on the workpiece according to the processing conditions, the shape of the workpiece to be processed and the processing requirements, so as to realize the effective combination of the laser beam and the workpiece.
(2) Composition of laser light guide and focusing system:
The laser light guide and focusing system of the small CO2 laser cutting machine consists of a light guide system composed of totally reflecting mirrors and a focusing system composed of focusing mirrors, as shown in the figure.
4. laser cutting system
(1)Control system composition:
The main control objects of the laser cutting machine control system contains the laser, the stepper motor driver in the movement mechanism, the blowing and exhaust fan and the chiller, as shown in the figure.
(2) Control system software and hardware composition:
the control system hardware comprises an industrial personal computer, control panel, main control card, interface board, driver, stepping motor, etc.
(3) The central controller works:
The central controller receives the operation and control commands from the computer and the panel to complete the work of controlling the operation of the motor, controlling the laser generation system, and monitoring and prompting various control States.
(4)Hardware composition of control system:
The control panel includes start, laser high voltage, reset, manual light output, pause, direction and other buttons as well as status indicator and laser energy regulator.
The control system software supports PLT, BMP and DXF file formats generated by various general graphics software, and adopts a mixed working mode of vector and dot matrix to complete engraving and cutting work.
5. Laser cutting machine sensing and detection system case
The positive and negative stroke limit system of X-axis is as shown in the figure.
6. Laser cutting machine cooling and auxiliary system
The laser cutting machine’s cooling and the auxiliary system comprises cooling accessories such as an exhaust fan, blowing pump, water chiller, and cutting platform.
(1) Cutting platform:
There are two types of cutting platforms. The honeycomb platform is suitable for processing cloth, leather, and other soft materials, as shown in the figure; the other is the blade platform, ideal for processing plexiglass, thick plates, and other hard materials, as shown in the figure.
As shown in the figure. Some equipment with high adsorption requirements has vacuum adsorption platforms.