In the last article we discussed about the difference between laser cutting machine and plasma cutting machine. Besides the two, there are also other cutting techniques like water cutting and wire cutting. Then what are they? What are the differences? Which one should I buy for my work? Here today we will discuss about these cutting machines in details.
Laser cutting is the use of a focused high-power density laser beam to irradiate the work piece to quickly melt, vaporize, ablate by reaching the ignition point of the irradiated material. CO2 pulsed lasers are popular in material processing industry now. Generally speaking, laser cutting belongs to the thermal cutting methods.
Water cutting, also known as water jet, is a high-pressure water jet cutting technology, which is a machine that uses high-pressure water to cut materials. Under the control of the computer, the work piece can be arbitrarily carved, and it is not affected by the texture of the material. Water cutting is divided into two methods: no sand cutting and sand cutting.
Plasma arc cutting is a processing method that uses the heat of a high-temperature plasma arc to locally melt (and evaporate) the metal at the incision of the work piece, and uses the momentum of the high-speed plasma to remove the molten metal to form an incision.
Wirecut Electrical Discharge Machining (WEDM for short) belongs to the category of electrical machining, so the wirecut electrical discharge machining, sometimes also called wire cutting directly.
Wire cutting can be divided into fast-moving wire cutting, medium-moving wire cutting, and slow-moving wire cutting. The wire speed of the fast type is 6-12m/s, but the electrode wire moves back and forth at high speed, making a poor cutting accuracy. Medium wire EDM is a new technology developed in recent years to realize the function of frequency conversion of multiple cutting on the basis of fast wire cutting. The wire speed of the slow wire EDM cutting is 0.2m/s, and the electrode wire moves in one direction at a low speed, so the cutting accuracy is very high.
The application range of laser cutting machine is very wide. Regardless of metal or non-metal, it can cut and cut non-metal, such as cloth, leather, etc. You can use CO2 laser cutting machine, and cutting metal can use fiber laser cutting machine. The deformation of the plate is small.
Water cutting is cold cutting, no thermal deformation, good quality of the cutting surface, no secondary processing, and easy secondary processing if necessary. Water cutting can perforate 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 precision, and is not easy to perform secondary processing on the cut surface.
Wire cutting can only cut conductive materials, and coolant is required during the process, so materials that are not conductive, afraid of water, or afraid of contamination by cutting coolant, such as paper and leather, cannot be cut by this technique.
The industrial application of laser cutting carbon steel is generally below 20mm and the cutting capacity is generally below 40mm. For industrial application of stainless steel, it is generally below 16mm, and the cutting capacity is generally below 25mm. As the thickness of the work piece increases, the cutting speed decreases significantly.
Water cutting technique can deal with thickness from 0.8mm to 100mm. Thicker material is also accessible but the cutting effect can not be good enough.
The plasma cutting thickness is 0-120mm. For the cutting thickness around 20mm, plasma cutting has the highest performance and best cutting quality.
The thickness of wire cutting is generally 40-60 mm. Among all of the cutting machines, it can cut the thickest materials with best cutting efficiency and effect, the top thickness of it can reach to 600 mm (though we don’t recommend to do that).
Using a laser with a power of 1200W to cut 2mm thick low-carbon steel plates, the cutting speed can reach to 600cm/min; for cutting 5mm thick polypropylene resin plates, the cutting speed can reach 1200cm/min. The cutting efficiency that can be achieved by wire EDM is generally 20-60 mm2/min and 300 mm2/min at most. Obviously, the laser cutting speed is fast and is more suitable for mass production.
The water cutting speed is quite slow and not suitable for mass production. But for small-size cutting, taking cutting steel board for example, the water cutting speed is usually at 80mm-160mm/min. This number also varies according to your level of water knife--high-end knife can reach 180mm/min while cheap water knife can only work at 80mm/min at most.
The cutting speed of plasma cutting is slow, the relative accuracy is low, and it is more suitable for cutting thick plates, but the end surface has a slope.
For metal processing, wire cutting has higher precision, but the speed is very slow. Sometimes other methods are needed to punch and thread to cut, and the cutting size is greatly limited.
The incision made by the laser cutting is narrow, and the two sides of the seam are parallel and perpendicular to the surface. The dimensional accuracy of the cut parts can reach to 0.2mm and the plasma can be within 1mm.
Water cutting will not produce thermal deformation, so the accuracy can be 0.1mm. If a dynamic water jet cutting machine is used, the cutting accuracy can be improved to 0.02mm and eliminate the cutting slope. The machining accuracy of wire cutting is generally ±0.01～±0.02mm, and the highest can reach ±0.004mm.
Laser cutting is more precise than plasma cutting, and the slit is small, about 0.5mm. Plasma cutting is larger than laser cutting, about 1-2mm;
The cutting seam of water cutting is about 10% larger than the diameter of the knife tube, generally between 0.8mm and 1.2mm. As the diameter of the sand knife tube expands, the incision becomes larger.
The width of the slit for wire cutting is the smallest, generally about 0.1 to 0.2 mm.
The surface roughness of laser cutting is not as good as water cutting, the thicker the material is, the more obvious it will be.
Water cutting will not change the texture of the material around the cutting seam while fiber laser is a thermal cutting and will change the texture of the cutting area.
Different models of laser cutting machines have different prices. Cheap ones such as carbon dioxide laser cutting machines cost only $3000 to $5000, and expensive ones such as 1000W fiber laser cutting machines now cost more than one million. Laser cutting does not have consumables, but the equipment investment cost is the highest among all cutting methods. What’s more, the use and maintenance costs are also quite high of laser cutting machine. Plasma cutting machines are much cheaper than laser cutting machines. Plasma cutting machines have different power, brands, etc., also the prices are different, but the same with laser machine, it has high cost. Basically, as long as they can cut conductive materials, the price can be neck and neck.
The cost of water cutting equipment is second only to laser cutting. It has high energy consumption and high maintenance costs. The cutting speed is not as fast as plasma. Because all abrasives are disposable, they are discharged into nature after they are used once, then it will cause serious environmental pollution.
Wire cutting is generally around $4000. But there are consumables for wire cutting, such as molybdenum wire and cutting coolant. There are two commonly used wires for wire cutting. One is molybdenum wire (molybdenum is quite precious), which is used in fast-moving wire equipment and can be disposable. Another material is copper wire. It is much cheaper and usually used in slow wire equipment. Its disadvantage is that the copper wire can only be used once. In addition, the fast-moving wire machine is far cheaper than the slow-moving wire machine. The price difference can be 5 times.
All in all, before buying a machine, two things you need to consider first: material thickness and budget.
For friends in European, please kindly check your environmental protection policy first to decide which one to choose and if there is a protective cover needed.
