The emergence of advanced engineering materials, stringent design requirements, intricate shape, and unusual size of the workpiece restrict the use of conventional machining methods. Hence it was realized to develop some nonconventional machining methods known as advanced machining processes.
Nowadays many advanced machining processes are being used in the industry such as Electro Discharge Machining, Laser Beam Machining, Electron Beam Machining, Ion Beam Machining, Chemical Machining Processes, Ultrasonic Machining, Jet Machining Processes.
In this topic, we are going to discuss Laser Beam Machining (LBM). But before going to the main topic, we will see what is LASER?
Principle of Laser Beam Machining
- Chemical degradation
When a high energy density of the laser beam is focused on the work surface, thermal energy is absorbed which heats and transforms the work volume into a molten, vaporized, or chemically changed state that can be easily removed by the flow of high-pressure that assist gas jet.
Construction of Laser Beam Machining (LBM)
The laser beam machining setup is shown in the figure below.
|Laser Beam Machining|
It consists of a stimulating light source (Xenon flash lamp) and a laser rod. A laser rod or Laser tube consists of a pair of mirrors, which are placed at each end of a tube.
This setup also consists of a flash tube/lamp (i.e. energy source), laser, power source, focusing source, and cooling system. The whole setup is fitted in an enclosure that has a highly reflective surface inside it.
Working of Laser Beam Machining
Laser Machining System
Fig (a) is a spiral flash lamp in which a ruby rod is kept inside the lamp.
Fig (b) is a straight flash lamp and cylindrical mirror with an elliptical cross-section.
Fig (c) is another laser machining system in which a circular reflecting cylinder is shown.
Laser Beam Machining Advantages and Disadvantages
Laser beam machining advantages and disadvantages are discussed below.
Advantages of Laser Beam Machining
- In the Laser beam Machining (LBM) process there is no direct contact between the tool and the workpiece, hence there is no issue of tool wear.
- Machining can be done in any environment.
- Refractory materials can be easily worked.
- Easy machining of brittle, non-metallic, and hard materials.
- Used for welding of dissimilar metals.
- Extremely small holes can be drilled easily.
Disadvantages of Laser Beam Machining
- LBM is applicable only for thin sections and where a small quantity of material is removed.
- Control of hole size is difficult.
- Holes drilled may have a slight taper formation, hence not suitable for large holes.
- The durability and reliability of the system are limited.
- Due to the low production rate, the efficiency of the system is low.
- The initial cost and operating cost of the system are high.
- Highly skilled operators are required.
Applications of Laser Beam Machining
- LBM is used for the trimming of sheet metal, carbon resistors, and plastic parts.
- It is used for drilling small holes in the materials like tungsten, ceramics which are very hard.
- LBM is also suitable for dynamic balancing of precise rotating components lie watches.
- Cutting complicated profiles on thin films for making Integrated Circuits, engraving patterns on suitable thin films or sheets.