1. Thermal cutting and its process characteristics:
Thermal cutting refers to the process of using heat, electrical energy, or chemical energy to heat the metal to above its melting temperature, make the metal pseudo-melted or semi-melted, and then use fluid power to remove, blow, or burn the metal to achieve cutting or removal of metal.
The common characteristics of the thermal cutting process are that a large amount of heat and metal oxides must be generated during the operation, and the working environment is poor, accompanied by a large amount of heat, smoke, dust, noise, and light pollution.
2. Introduction to common thermal cutting processes
1. Flame cutting
Flame cutting is a cutting method that uses a flame formed by the combustion of combustible gas, combustible solid or liquid fuel gasification mixed with oxygen or air to heat the workpiece to melt it, and uses the high temperature generated during the combustion of iron oxide to burn the metal, and then blows it away with a fluid. Gas cutting is a method of cutting by preheating the workpiece to a certain temperature with the flame heat of a mixture of combustible gas and oxygen, then ejecting a high-speed cutting oxygen flow to cause the metal to oxidize violently and release heat, and using the cutting oxygen flow to blow away the molten metal oxides.
The gas-cutting process of metal is essentially the combustion process of iron in pure oxygen rather than the melting process. The mixing of combustible gas and oxygen and the injection of cutting oxygen are completed by a cutting torch. The combustible gases used in gas cutting are mainly acetylene, liquefied petroleum gas, and hydrogen.
Except for the cutting torch, the equipment and tools used in gas cutting are the same as those for gas welding. The gas-cutting process is a preheating-combustion-slag-blowing process, but not all metals can meet the requirements of this process. The metals that can be gas cut include pure iron, low carbon steel, medium carbon steel, low alloy steel, and copper, while cast iron, stainless steel, aluminum, and copper are difficult to gas cut.
Flame cutting is the oldest thermal cutting process method. It can cut metal thickness from 1 mm to 1m. Flame-cutting equipment is low-cost and is the only economical and effective means of cutting thick metal plates, but it has its shortcomings in cutting thin plates. Common flames used for flame cutting include acetylene flame, petroleum gas flame, coal gas flame, natural gas flame, etc.
2. Carbon arc gouging
Carbon arc gouging is a method of gouging metal by using the high temperature of the carbon arc to melt the metal and then blowing off the molten metal with compressed air. Carbon arc gouging has the advantages of high efficiency, low noise, low price, and wide applicability. It has been widely used in casting, boilers, shipbuilding, chemical industry, and other industries.
3. Plasma arc cutting
Plasma arc cutting is a commonly used thermal cutting process for metal and non-metal materials. It uses high-speed, high-temperature, and high-energy plasma airflow to heat and melt the cut material, and uses internal or external high-speed airflow or water flow to push the molten material away until the plasma airflow beam penetrates the back to form a cut.
The temperature of the plasma arc pit is high, far exceeding the melting point of all metals and non-metals. Therefore, the plasma arc cutting process does not rely on oxidation reaction, but on melting to cut materials, so it is much more applicable than the oxidation cutting method and can cut most metals and non-metallic materials. The use of annular airflow technology to form a slender and stable plasma arc ensures that any conductive metal can be cut smoothly and economically.
4. Laser cutting
Laser cutting uses the energy released when the laser beam is irradiated on the surface of the workpiece to melt and evaporate the workpiece to achieve the purpose of cutting. It has the characteristics of high precision, fast cutting, no restrictions on cutting patterns, and smooth incisions.
There are three types of laser cutting: laser melting cutting, laser flame cutting, and laser gasification cutting. In laser melting cutting, the workpiece is partially melted and the molten material is ejected with the help of airflow. Because the transfer of material only occurs in its liquid state, the process is called laser melting cutting.
The difference between laser flame cutting and laser melting cutting is that oxygen is used as the cutting gas, and the interaction between oxygen and the heated metal produces a chemical reaction to further heat the material. Due to this effect, for structural steels of the same thickness, higher cutting rates can be achieved with this method than with fusion cutting.
During laser vaporization cutting, the material vaporizes at the cut, which requires very high laser powers. Laser cutting is often classified as cold cutting.
The above is all about the thermal cutting process. I hope you like it.
