There are four common cutting methods, namely: laser cutting, water jet cutting, plasma cutting and wire electrical discharge machining. This article will briefly introduce the definitions of them, and make a multi-dimensional and all-round comparison of their application range, cutting thickness, cutting accuracy, cutting speed, cutting seam width, cutting quality and production cost.
1. Definition of four cutting methods
Laser cutting is to use the focused high-power density laser beam to irradiate the work-piece, so that the irradiated material quickly melts, vaporizes, ablates or reaches the ignition point, and at the same time, the molten material is blown away by the high-speed airflow coaxial with the beam, so as to cut the work-piece. It belongs to thermal cutting.
Water jet cutting, also known as water knife, refers to high-pressure water jet cutting technology. It is a machine that uses high-pressure water flow to cut. It can be divided into two ways: non sand cutting and sand adding cutting. water jet cutting can be controlled by computer to carve any work-piece, and it is less affected by the material texture, and will not generate a lot of heat like other cutting methods.
Plasma cutting is a machining method that uses the heat of high-temperature plasma arc to locally melt (and evaporate) the metal at the work-piece notch, and uses the momentum of high-speed plasma to remove the molten metal to form a notch.
The full name of wire electrical discharge machining is wire electrical discharge machining, which belongs to the category of electrical machining. wire electrical discharge machining can be divided into fast wire electrical discharge machining, medium wire electrical discharge machining and slow wire electrical discharge machining according to the different wire speed. The wire speed of fast wire EDM is 6 ~ 12m / s, the electrode wire moves back and forth at high speed, and the cutting accuracy is poor. Medium wire EDM is a new technology developed in recent years, which realizes frequency conversion multiple cutting function on the basis of fast wire EDM. The wire speed of slow wire EDM is 0.2m/s, and the wire electrode moves at low speed and unidirectionally, so the cutting accuracy is very high.
2. Comparison of application scope
Laser cutting machine has a wide range of applications, whether metal or non-metallic materials can be cut. CO2 laser cutter can be used to cut non-metallic materials, such as cloth and leather; The fiber laser cutter can be used to cut metal materials, and the deformation of the plate is small.
Water jet cutting belongs to cold cutting, with no thermal deformation, good cutting surface quality, and no secondary processing (it is easy to carry out secondary processing if necessary). Water jet cutting can punch and cut any material, with fast cutting speed and flexible processing size.
Plasma cutting machine can be used for cutting various metal materials such as stainless steel, aluminum, copper, cast iron, carbon steel, etc. plasma cutting has obvious thermal effect, low accuracy, and it is not easy to re process the cutting surface.
Wire electrical discharge machining can only cut conductive materials, and coolant is required in the cutting process. Therefore, wire electrical discharge machining cannot be applied when cutting non-conductive materials such as paper and leather, which are afraid of water and coolant pollution.
3. Comparison of cutting thickness
The application of laser cutting carbon steel in industry is generally below 20mm, and the cutting capacity is generally below 40mm. The industrial application of stainless steel is generally below 16mm, and the cutting capacity is generally below 25mm. And with the increase of work-piece thickness, the cutting speed decreases obviously.
Water jet cutting has great advantages in cutting thickness, which can cut materials within 0.8 to 100mm or even thicker
The plasma cutting thickness range is between 0-120mm, and the plasma system with the best cutting quality range of about 20mm has the highest cost performance ratio.
The thickness of wire electrical discharge machining is generally 40 ~ 60mm, and the maximum thickness can reach 600mm.
4. Cutting speed comparison
Cutting 2mm thick low carbon steel plate with 1200W laser, cutting speed up to 600cm / min; The cutting speed can reach 1200cm / min when cutting 5mm thick polypropylene resin plate. The cutting efficiency that WEDM can achieve is generally 20-60 mm2 / min, and up to 300 mm2 / min. In contrast, it is obvious that the laser cutting speed is fast and can be used for mass production.
The water jet cutting speed is very slow, which is not suitable for mass production.
Plasma cutting has slow cutting speed and low relative accuracy, which is more suitable for cutting thick plates, but the end face has slope.
For metal processing, wire electrical discharge machining has higher accuracy, but the speed is very slow. Sometimes, it needs to be punched and threaded by other methods to cut, and the cutting size is very limited.
5. Comparison of cutting accuracy
The laser cutting incision is thin and narrow, and the two sides of the slit are parallel and perpendicular to the surface. The dimensional accuracy of the cut parts can reach ± 0.2mm. In contrast, the plasma cutting accuracy is within 1mm. Water jet cutting will not produce thermal deformation, and the accuracy is ± 0.1mm. If a dynamic water jet cutting machine is used, the cutting accuracy can be improved, and the cutting accuracy can reach ± 0.02mm, eliminating the cutting slope. The machining accuracy of wire electrical discharge machining is generally ± 0.01 - ± 0.02mm, and the maximum is ± 0.004mm.
6. Comparison of cutting width
Compared with plasma cutting, laser cutting is more precise and has a small slit of about 0.5mm. Plasma cutting slit is larger than laser cutting, about 1-2mm. The water jet cut slit is about 10% larger than the diameter of the cutter tube, generally 0.8mm-1.2mm. As the diameter of the sand knife tube flares, the incision becomes larger. The seam width of wire electrical discharge machining is the smallest, generally about 0.1-0.2mm.
7. Comparison of cutting surface quality
The surface accuracy of laser cutting is not as good as that of water jet cutting, and the thicker the material, the more obvious. As it belongs to cold cutting, water jet cutting will not change the texture of materials around the cutting seam, while laser cutting belongs to thermal cutting, which will change the texture of materials around the cutting area.
8. Comparison of production cost
Different types of laser cutting machines have different prices. Cheap CO2 laser cutting machines only cost 20,000 to 30,000 RMB, while expensive 1000 W fiber laser cutting machines now cost even more than 1 million RMB. There are no consumables for laser cutting, but the equipment investment cost is relatively high in all cutting methods. The plasma cutting machine is much cheaper than the laser cutting machine. According to the power and brand of the plasma cutting machine, the price varies, and the use cost is high. Basically, as long as it can cut conductive materials.
The cost of water jet cutting equipment is second only to laser cutting, with high energy consumption and high use and maintenance costs. And the water jet cutting speed is not as fast as plasma cutting. In addition, because all abrasives are disposable, they are discharged into the nature after being used once, so the environmental pollution caused by water jet cutting is also relatively serious.
Wire electrical discharge machining is generally about tens of thousands of pieces. However, wire electrical discharge machining has consumables, including molybdenum wire and cutting coolant. There are two kinds of wire commonly used in wire electrical discharge machining, one is molybdenum wire (higher price), which is used for fast wire walking equipment. The advantage of molybdenum wire is that it can be reused many times. The other is to use copper wire (cheaper than molybdenum wire) for slow wire walking equipment. The disadvantage is that copper wire can only be used once. In addition, the fast wire walking machine is far cheaper than the slow wire walking machine, and the price of the latter is almost five to six times that of the former.
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Four Industrial Cutting Methods and their Comparative Advantages
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