For cutting metals, various methods such as laser cutting, waterjet cutting, air cutting, plasma cutting, cutting with cutting blades and etc. can be used. Laser cutting is used in cases where the user wants to cut metals with a low thickness (usually less than 8 mm) and also when the desired tolerance is low or in other words, the cutting accuracy is high. Of course, there are laser devices that can cut steel up to a few centimeters, but their use is not common due to their high purchase costs and high electrical power consumption.
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Introduction of different methods of metal cutting
Older methods of metal cutting include milling, lathing, air-gas cutting, plasma cutting, waterjet cutting and guillotine cutting. The thickness of the cut in all these methods varies from 1 mm to 200 mm. In contrast, today, there is the modern method of laser cutting, which is used for cutting metals in most cases due to the accuracy of micrometer cutting (a thousand times more accurate than the old methods), time and cost savings, as well as higher quality of cutting. The following is a brief description of the methods of metal cutting.
Milling: This method is one of the oldest methods of cutting metals.
Lathing: In lathing, the cutting of the material is done in a circular manner and has the ability to produce various shapes including conical shapes, by changing the position of the device.
Grinding: In this method, abrasion by stone is used to remove the material from the metal surface and is generally used to produce high quality surfaces. Also, the removed thickness from the material piece is low.
Sanding: This method uses abrasion like grinding, with the difference that the amount of load removed from the material is much less than grinding.
Threading: There are different methods for producing bolts and threading, such as using screw thread, using milling or turning machines, rolling and forming.
Because of time and cost savings as well as higher quality, there are modern methods of metal cutting that are used more than traditional methods. The most common methods are:
Air cutting: Air cutting is a very old method and is used for cutting iron and steel. This method is very convenient due to the production of clean and precise edges. Commonly, this method is used for thicknesses of 10 to 2000 mm, but it can also be used for thicknesses of 6 to 300 mm by using a series of methods.
Plasma cutting: This method is used in many works due to its vast variety in price and workmanship. Also, it is faster than the air gas method and can be used for cutting metals in the range of 1 mm to 30 mm. This range can also be increased between 0.5 mm to 160 mm, by using special units.
Laser cutting: Laser cutting is used as one of the modern methods in the range of 10 to 25 mm. Laser has high accuracy and quality in metal cutting. Also, using this method is very easy and the cutting work can be done without the operator. The laser has a high speed at low thicknesses but its speed decreases severely at high thicknesses. Different types of lasers are used to cut different metals.
Waterjet cutting: In waterjet cutting, metals are cut very accurately using water pressure. The quality of the edges in this method is even better than the laser cutting of metals, because it does not create any heat stress for the metal. This method is applicable for any types of metals with any thicknesses.
Cutting sheets with guillotine: One of the fast and optimal methods for cutting metal sheets is cutting sheets with guillotine. In this method, a very clean and rectangular cut is made. This device creates cuts with suitable angle and pressure and is equipped with CNC, which is used to control the activity of the device by adjusting the distance between the blades and adjusting the flow for different types of sheets.
Advantages of laser cutting over traditional methods
The speed of the laser pulse is about 100 nanoseconds in laser cutting (one million times faster than 0.1 seconds). At this speed, the material piece is cut before heating and deformation. As a result, in laser cutting, no burns will be observed on the surface of the material and the pleat behind the material. Also, the mechanical and physical properties of the material will be preserved.
During the cutting, the laser device has no contact with the surface of the material and the physical pressure is not applied to the material. So there won’t be crushing at the edges of the material.
Due to the high power of the laser source, laser devices have a high speed for laser cutting of the material.
The cross-sectional area of the laser spot in the laser cutting is between 30 and 100 micrometers. This makes the accuracy of laser cutting at least a thousand times higher than the traditional methods. As a result, the laser machine can make holes and cuts with dimensions of 50 micrometers. But, this accuracy varies depending on the thickness of the material.
The beam of the cutting laser is incident on the surface with a CNC device and a shape is designed digitally by using a computer, without hand intervention. The advantages of using CNC laser cutting machines are as follows:
1. Very high precision in cutting without creating pleats up to 0.1 mm
2. Complex designs, two-dimensional drawings and any drawn designs by tools such as AutoCAD and … can be implemented in metal laser cutting technology, easily.
3. In laser cutting, you do not require traditional methods (molding and pressing) and the material parts do not need to be re-machined after CNC laser cutting.
4. Creation of any desired and complex shape in the material based on the customer's wishes without restrictions
5. High level smoothness of the surface
6. Since the laser does not come into contact with the material, no contact stress is created and the focusing accuracy in laser cutting is maintained.
7. No burns due to cutting
8. Low material waste
Therefore, due to their micrometer accuracy and lack of burns and stress in the material, it can be said that cutting lasers are widely used in various industries such as military, construction, aerospace, medicine, laboratory and research, communications, physics, chemistry and etc.