Today we will learn about laser beam machining principle, working, equipment’s, application, advantages and disadvantages with its diagram. Laser beam machining is a thermal machining process which uses laser beam to produce heat. In this machining process metal is removed by melting and vaporization of metal particle from surface of work piece. It is a non-conventional machining process in which no tool is used. It is used to machine both metallic and non-metallic material. It is mostly used in cutting and drilling operation.
Laser Beam Machining:
The word laser stands for Light amplification by Stimulated Emission of Radiation. When an electron of atom absorbed energy form an external source, the electron which are in its original energy level, jump to a higher energy level. This is not a stable condition of atom so this electron emits the absorbed energy in form of photons and come back to its original state. If an atom which is already at higher energy level absorbs energy, it will emit double energy to return at its original state. The energy emitted by the atom has same frequency and wavelength as the stimulating energy. This is fundamental of laser. When the laser material placed in presence of some other energy source, it absorb energy at some extant and release it when reaches its absorbing limit. This high amplified light beam is called laser.
|Principle of Laser Beam Welding|
This machining process works on basic property of laser. It uses a laser beam, which is a narrow, monochromatic high intense light which can cut or machine any metal and non-metal. It can use to cut any material irrespective to hardness of work piece. It can also use to cut diamond which is hardest known material on earth.
|Laser Beam Machining|
It provides the energy for excitation of electron from lower energy level to higher energy level. This gives power to xenon flash lamps, which produce light energy. The laser material are exposed in light energy to keep storing energy.
Laser Discharge Tube:
The laser material filled in lased discharge tube. The excitation of electron and come back to its original state process takes place in it. It’s one side is partially transparent for laser opening and other side is 100% reflected. It is situated between flash lamp.
There are many different type of laser material available but in later machining mostly CO2(Pulsed or continuous waves) and Nd: YAG is Used. Carbon die oxide is a laser material that emits light in infrared region. It can provide up to 25 KW power in continuous wave mode. The other one is called Neodymium doped Yttrium Aluminum Garnet is a solid state laser which can delivery light through optical fiber. It can generate about 50 KW power in pulsed mode and 1 KW power in continuous mode.
A focusing lens is used in laser machining operation. It is a convex lens which focus is at work piece.
As we know in laser energy is used to remove metal from workpiece. Its process can be summarized as follow.
- First laser material CO2 or other gases filled into laser discharge tube.
- Now switch on the power supplied which is connected by flash lamp. This lamps produce light energy which used to excite electrons of atom.
- The atoms of laser material absorb energy from the light energy produced by flash lamp. It leads jump of orbital electron of atom form low energy level to high energy level. This is unstable condition of atom.
- This energy initially blind up in laser material. When the atoms absorb sufficient energy it start emit energy continuously. This is high amplified same frequency and same wavelength coherent light.
- This laser light collected by the focus lens and directed toward the work piece.
- Now the laser impinging on work piece start machining process by melting or vaporize material from contact surface.
This is whole process of laser beam machining.
- Used to drill small hole of diameter about 0.005 mm in refectory and ceramic materials.
- It is used in drilling and cutting for both metals and non-metals.
- It is extensively used in electronic and automotive industries.
- It is mostly used in aerospace industries.
- Used to machine complex profile where machining by tool is not possible.
Advantages and Disadvantages:
- It can cut all material.
- No tooling cost because no physical tool is required.
- It produces finish part or high surface finish.
- No tool wear because no physical tool is used.
- Micro holes can be drilled accurately.
- Complex shape can be machined easily because laser can be move in any path.
- Very hard material can be cut through laser beam machining.
- High accuracy can be achieved.
- It can be easily automated and flexible.
- It is uneconomical when high volume of same shape to be cut compare to stamping.
- High capital and maintenance cost.
- It cannot use to produce blind hole.
- Laser can leads to safety hazards.
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