What Is Laser Beam Machining?
Laser beam machining (LBM) is a form of machining that uses heat directed from a laser beam. This process uses thermal energy to remove material from metallic or nonmetallic surfaces. The high frequency of monochromatic light will fall on the surface then heating, melting, and vaporizing of the material take place due to impinging of photons.
Laser beam machining is best suited for brittle materials with low conductivity but can be used on most materials.
Laser beam machining can be done on glass without melting the surface. With photosensitive glass, the laser alters the chemical structure of the glass allowing it to be selectively etched. The glass is also referred to as photo machinable glass.
The advantage of photo machinable glass is that it can produce precisely vertical walls and the native glass is suitable for many biological applications such as substrates for genetic analysis.
Definition of Laser Beam Machining
A laser beam machining is a non-conventional machining method in which the operation is performed by laser light. The laser light has maximum temperature strikes on the workpiece; due to high temp, the workpiece gets melts. The process used thermal energy to remove material from a metallic surface.
Types of lasers
There are many different types of lasers including gas, solid states lasers, and excimer.
Some of the most commonly used gases consist of; He-Ne, Ar, and Carbon dioxide laser.
Solid-state lasers are designed by doping a rare element into various host materials. Unlike gas lasers, solid-state lasers are pumped optically by flash lamps or arc lamps. Ruby is one of the frequently used host materials in this type of laser.
A ruby laser is a type of solid-state laser whose laser medium is a synthetic ruby crystal. The synthetic ruby rod is optically pumped using a xenon flashtube before it is used as an active laser medium.
YAG is an abbreviation for yttrium aluminum garnet which are crystals that are used for solid-state lasers while Nd: YAG refers to neodymium-doped yttrium aluminum garnet crystals that are used in the solid-state lasers as the laser mediate.
YAG lasers emit a wavelength of light waves with high energy. Nd: glass is neodymium-doped gain media made of either silicate or phosphate materials that are used in a fiber laser.
Parts of Laser Beam Machining
1. Power Supply
A high voltage is required for Laser. The power is supplied to the system for exiting the electron. When the power is supplied the electron gets in an excited state that means ready to work.
2. Flash Lamps
Flash lamps are used for providing white and coherent light for a very short duration.
In general, we know the work of capacitor, it is used for storing and releasing the charge. Here it is used during the flashing process.
4. Reflecting Mirror
A reflecting Mirror is used here to reflect the light directly to the workpiece. It is of two types Internal and external.
Lenses are provided here for vision purposes. It shows the image in a bigger size so that it will be easy to perform an operation on the given workpiece mark.
The workpiece is like the object in which the operation is to be carried out. For example, if the body needed any laser operation then we are the workpiece for this machine, same like manufacturing the objects need to be drill or hole the Laser machine carried out the operation.
Working Principle of Laser Beam Machining
In this process, the Laser Beam is called monochromatic light, which is made to focus on the workpiece to be machined by a lens to give extremely high energy density to melt and vaporize any material.
The Laser Crystal (Ruby) is in the form of a cylinder as shown in the above figure or Diagram with flat reflecting ends which are placed in a flash lamp coil of about 1000W.
The Flash is simulated with the high-intensity white light from Xenon. The Crystal gets excited and emits the laser beam which is focused on the workpiece by using the lens.
The beam produced is extremely narrow and can be focused to a pinpoint area with a power density of 1000 kW/cm2. Which produces high heat and the portion of the metal is melted and vaporized.
Applications of Laser beam machining
Lasers can be used for welding, cladding, marking, surface treatment, drilling, and cutting among other manufacturing processes. It is used in the automobile, shipbuilding, aerospace, steel, electronics, and medical industries for the precision machining of complex parts.
Laser welding is advantageous in that it can weld at speeds of up to 100 mm/s as well as the ability to weld dissimilar metals. Laser cladding is used to coat cheap or weak parts with harder material in order to improve the surface quality. Drilling and cutting with lasers are advantageous in that there is little to no wear on the cutting tool as there is no contact to cause damage.
Milling with a laser is a three-dimensional process that requires two lasers, but drastically cuts the costs of machining parts. Lasers can be used to change the surface properties of a workpiece.
The appliance of laser beam machining varies depending on the industry. In light manufacturing the machine is used to engrave and to drill other metals. In the electronic industry, laser beam machining is used for wire stripping and skiving circuits. In the medical industry, it is used for cosmetic surgery and hair removal.
Advantages of Laser beam machining
- Since the rays of a laser beam are monochromatic and parallel (i.e., zero etendue) it can be focused to a small diameter and can produce as much as 100 MW of power for a square millimeter of area.
- Laser beam machining has the ability to engrave or cut nearly all materials, where traditional cutting methods may fall short.
- There are several types of lasers, and each have different uses.
- The cost of maintaining lasers is moderately low due to the low rate of wear and tear, as there is no physical contact between the tool and the workpiece.
- The machining provided by laser beams is high precision, and most of these processes do not require additional finishing.
- Laser beams can be paired with gases to help the cutting process be more efficient, help minimize oxidization of surfaces, and/or keep the workpiece surface free from melted or vaporized material.
Disadvantages of Laser beam machining
- The initial cost of acquiring a laser beam is moderately high. There are many accessories that aid in the machining process, and as most of these accessories are as important as the laser beam itself the startup cost of machining is raised further.
- Handling and maintaining the machining requires highly trained individuals. Operating the laser beam is comparatively technical, and services from an expert may be required.
- Laser beams are not designed to produce mass metal processes.
- Laser beam machining consumes a lot of energy.
- Deep cuts are difficult with workpieces with high melting points and usually cause a taper.