by Tianchen Laser
In the field of metalworking applications, users often face the problem of how to choose the most suitable metal cutting process. In fact, the current mainstream metal cutting processes have their own characteristics in terms of cutting thickness, cutting accuracy, metallurgical properties, and production efficiency.
This article can not exhaust all the above details, can only do some summary and hope to bring you a better understanding.
Below is a brief description of these different processes, including flame cutting, fine plasma, 3 kW fiber laser and waterjet. For comparison, I will use the full system equipment purchase cost, including 5' x 10' (about 1.5 x 3 m) cutting area, an industrial CNC machine (neither entry level nor top configuration), CAD/CAM software.
1 flame cutting
The flame cutting process is the simplest of all the cutting techniques we discuss here. The principle is to first heat the steel to the "flame point" temperature (about 1800F) with a combustible gas. Once the temperature is reached by preheating, the pure oxygen is injected into the hot steel to generate an exothermic reaction, which quickly erodes the steel. The flame can only be cut with carbon steel and main used in thicknesses from 1/4" (about 6.35mm) to 6" (about 150mm). Cutting speeds are faster than other processes at thicknesses greater than 2" (about 50 mm). It is easy and inexpensive to install multiple flame torches on a single CNC machine, which doubles capacity.
5' x 10' flame cutting bed cost: 8-180,000 RMB (relatively simple machine with low speed) Cutting cost per unit or unit length: quite a lot of gas, slow cutting speed. The thicker the steel plate, the more advantageous the cutting cost relative to the plasma. Cutting costs per foot are typically higher than plasma, and when the thickness is more than 2" (about 50 mm), the cost is relatively low.
Ease of use: The flame CNC cutting table requires the operator to be experienced in order to achieve the fastest cutting speed and the best cutting quality. It is often necessary to monitor the cutting process all the time.
Productivity: Flame cutting is very inefficient due to the long warm-up time and slow cutting speed.
Cutting part accuracy: a good operator at the most suitable speed, height, gas, nozzle, the dimensional tolerance of the cutting part is about plus or minus 0. 030" (about 0.76mm), the slope is less than 1 degree.
Edge quality, metallurgical properties: The heat affected zone of flame cutting is large. The section is rough and has a dross.
Maintenance requirements: The maintenance of the flame cutting bed is relatively simple and can be mastered by the user.
2 fine plasma
Fine plasma is a high-energy density cutting arc that uses high-temperature ionized gas to cut all conductive materials. The latest technology has no requirement for the experience of operators. Fine plasma is best suited for cutting 26 gauge (about 0.45mm) to 2" (about 50mm) thick carbon steel, as well as stainless steel and aluminum within 160mm thickness.
5' x 10' plasma cutting bed cost: 40-600,000 RMB (faster speed, equipped with height adjustment and dust removal) Cutting cost per unit or unit length: about 6.35mm to 2” (about 50mm) thick carbon steel, the cutting cost of plasma is the lowest compared to other processes.
Ease of use: With the latest CNC and software, the plasma is easy to learn and use. Since the professional process parameters are already built into the nesting software, there is no empirical requirement for the operator.
Productivity: When the thickness is greater than about 6.35 mm, the cutting speed is faster than the laser. When the thickness is less than 2" (about 50mm), the cutting speed is faster than the flame. Plasma is the fastest and most efficient in all cutting processes.
Cutting piece accuracy: The dimensional tolerance of carbon steel cutting parts is about plus or minus 0. 015" (about 0.38mm) to 0.020" (about 0.5mm). For sheets having a thickness of less than 3/8" (about 9.5 mm), the slope is 2-3 degrees. For thick sheets having a thickness greater than 1/2" (about 12.7 mm), the slope is within 1 degree.
Edge quality, metallurgical properties: The heat affected zone is small, usually less than 0.010" (about 0.25mm). The weldability of the section is good, smooth and no dross.
Maintenance requirements: Maintenance is relatively simple, the user can master it, or only the manufacturer's phone support.
3 fiber laser
Fiber laser is the latest laser technology. The solid-state laser generator used is more efficient than the conventional Co2 laser, and the wavelength of the fiber laser is suitable for conduction in a soft fiber, which is more flexible and easier to maintain than a Co2 laser that can only be transmitted by specular reflection. High-energy lasers focus on melting the material being cut, and auxiliary gases (usually using oxygen when cutting carbon steel) blow off the molten metal. A 3 kW fiber laser is equivalent to a 4 to 5 kW Co2 laser in terms of cutting capability and speed. Its cutting capacity is generally able to achieve carbon steel with a thickness of "about 19mm".
5' x 10' fiber laser cutting bed cost: 2 million to 3 million yuan (laser cutting bed requires higher motion accuracy and needs shading protection) cutting cost per unit or unit length: thickness less than ?" (about 6.35mm) At the time of laser cutting, the cost is the most advantageous. As the thickness increases, the cutting speed is significantly reduced. Although the cutting quality and precision are good, the cutting cost is higher than the plasma.
Ease of use: Similar to the latest plasma systems, with the latest CNC and software, the laser cutting bed is equally easy to learn and use, as all settings are automatic.
Productivity: The production efficiency is the highest on the sheet, and the thickness is increased to ?" (about 6.35mm), which is level with the plasma.
Cutting part accuracy: The best fiber laser cutting part size tolerance is about plus or minus 0.01" (about 0.25mm). It is better than plasma and can be compared with waterjet. The slope is within 1 degree.
Edge quality, metallurgical properties: The heat affected zone is slightly smaller than the plasma.
Maintenance requirements: Compared with the previous Co2 laser, the maintenance difficulty of the fiber laser is greatly reduced. Under the support of the manufacturer's phone, the user can generally master it.
Waterjet technology has been around for decades and has a wide range of applications from cake to granite. Soft materials can be cut with pure water, and high pressure water streams (40,000 to 60,000 psi) are compressed by nozzles to increase flow rate and energy density. It is also possible to add sand to the water stream, which acts like a saw tooth and is cut by the flow of water. The most advanced waterjet pump currently achieves 100,000 psi of high pressure water. Higher pressures mean faster cutting speeds, and of course downtime maintenance time increases because the pump seals need to be replaced periodically. The two biggest advantages of waterjets over other cutting processes are the absence of heat affected zones and the ability to cut almost any material. In addition, the cutting accuracy of the water jet is very good. But the biggest disadvantage of the waterjet is its slow cutting speed.
5' x 10' waterjet cutting machine cost: 50--900,000 RMB (because of slow speed, low performance requirements, cheaper than laser bed, slightly more expensive than plasma bed) Cutting cost per unit or unit length: due to water The cutting speed of the knife is too slow, so the cutting cost per unit part is the highest compared to other processes.
Ease of use: Similar to the latest plasma systems, with the latest CNC and software, the waterjet cutting table is equally easy to learn and use. The experience of the operator is very low.
Productivity: Very slow on carbon steel and stainless steel, cutting aluminum will hurry.
Cutting precision: The accuracy of the waterjet is the best among all cutting processes. The dimensional tolerance of the cutting part is about plus or minus 0.005" (about 0.13mm). The slope is within 1 degree.
Edge quality, metallurgical properties: no effect on the metallurgical properties of the material being cut. The section is smooth and the quality of the cut is related to the grit and the cutting speed (slower and smoother).
Maintenance requirements: Maintenance is relatively simple and the user can master it.
From a distance, the cutting samples of the five processes are similar. But when you look closer, the audience can see that the air plasma sample has a significant slope, especially a small hole. The cutting slope of the oxygen plasma is reduced, and the fine plasma hardly sees the slope.
It is true that it is unfair to compare only 1/2" (about 12.7mm) carbon steel. In this thickness range, laser cutting machines are undoubtedly the best choice.
But if we cut 1/8” (about 3mm) of aluminum, we believe that waterjets and lasers will be more efficient and more accurate.
If the size requirements are relaxed, inexpensive air plasma should be the best choice.
Therefore, first define your own needs and practical applications, and consider the various process characteristics described in this article. I believe that you will be able to choose the most suitable metal cutting process and equipment.
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