What is Laser Beam Machining?- Types and Working

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.

Laser beam machining (LBM)

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.

3. Capacitor

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.

5. Lense

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.

6. Workpiece

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.

FAQs.

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.

What is the advantage of Laser beam machining?

The main advantages of laser beam machining are ease of automation for complex cutting patterns, absence of tool wear and breakage, ability to cut at shallow angles, and rapid cutting rates. As it is a non-contact process, energy transfer between the laser and the material occurs through irradiation.

Which laser is used in Laser beam machining?

Types of lasers used for laser beam machining: Gas lasers such as CO2 and excimer lasers, along with solid-state lasers such as Nd:YAG and YAG lasers and femtosecond lasers, are some of the most popular lasers.

What is the principle of laser beam machining?

Focuses on the workpiece to mechanize this laser beam produced. When the laser beam hits the surfaces of the W/P, the thermal energy of the laser beam is transferred to the surfaces of the W/P. It heats, melts, evaporates, and eventually makes the material a workpiece.

What are the characteristics of laser beam?

In Chapter 1 it was stated that the most characteristic properties of laser beams are (i) monochromaticity, (ii) coherence (spatial and temporal), (iii) directionality, (iv) brightness.

Which laser material is used in LBM process?

There are a number of laser types developed in the solid-state category in which Nd:YAG is majorly used for LBM applications. Solid-state lasers such as Nd:YAG, ruby and Nd-glass are highly used for machining metallic materials. Nd:YAG lasers can also be used for ceramic materials.

What is laser manufacturing?

Laser-based manufacturing is currently applied in many different industries to process different kinds of materials, from ceramics to polymers and all the way to metals. Advances in laser technology have allowed the laser processing of virtually any material with unprecedented precision and efficiency.

Is Laser beam machining requiring vacuum during entire operation?

Explanation: Laser beam machining is more versatile and can be used for metal as well as non-metal. It does not require a vacuum environment. Explanation: In the laser beam machining process heat affected zone have a smaller area in comparison with other unconventional machining processes.

What are the types of lasers?

Based on their gain medium, lasers are classified into five main types:

  • Gas Lasers.
  • Solid-State Lasers.
  • Fiber Lasers.
  • Liquid Lasers (Dye Lasers)
  • Semiconductor Lasers (Laser Diodes)

What are the main properties and application of laser beams?

A laser is a device that projects a highly concentrated narrow beam of light that is amplified using stimulated radiation. Lasers have three properties: coherency, collimation, and monochromatic properties. These three properties of lasers produce a small focal point of intense power.

What materials can be machined using a laser beam?

Laser beam machining is independent of the electrically conductive nature of the workpiece. It can machine a wide range of materials from plastics to diamonds. Laser beam machining provides a wide range of material processing techniques ranging from drilling, cutting, grooving, scribing, marking, cleaning and turning, etc.

Why laser beam machining Cannot be used for larger holes?

Laser radiation exceeding a certain power density produces melting and vaporization of material and ejection of solid particles. With increasing diameter and depth of the hole, the ejected solid particles melt and deposit on the walls and the bottom of the holes, thus not suited for deep-hole drilling.

How is the operating cost of the machines used in laser beam machining?

Machining is very much rapid and the setup times are economical in Laser beam machining.

How is the operating cost of the machines used in Laser beam machining?

The operating cost of the machines in LBM is low but the equipment cost itself is of high cost.

What does laser technology do?

Laser devices use light to store, transfer, or print images and text; they are also used in a wide range of other applications, including surgery and weaponry. The coherent radiation of the laser gives it special strength.

What is population inversion in laser beam machining?

  • For laser action, the population of atoms in the. higher energy state should be increased. The process of increasing the population of higher energy level i.e., making N2 > N1 is called as population inversion.
  • The method of achieving population inversion is. called pumping.

What are the applications of laser machining?

Applications. 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.

Is electron beam used in laser beam machining?

A high-intensity beam of focused electrons is used to supply heat for material removal. A high-intensity beam of laser (coherent photons) is used to supply heat for material removal.

Who invented the laser beam?

Theodore Maiman of Hughes Research Laboratories, with the first working laser. Theodore Maiman developed the first working laser at Hughes Research Lab in 1960, and his paper describing the operation of the first laser was published in Nature three months later.

What is a Class 3 laser?

Class 3 lasers are medium power lasers or laser systems that require control measures to prevent viewing of the direct beam. Control measures emphasize preventing exposure of the eye to the primary or specularly reflected beam.

Is LBM a limitation?

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.

When was the laser beam invented?

December 1958: Invention of the Laser. Every now and then, a scientific breakthrough occurs that has a revolutionary impact on daily life. One example of this is the invention of the laser, which stands for light amplification by stimulated emission of radiation.

Can lasers cut metal?

Lasers can cut through many materials and are typically used on a select few types of metal — in particular, carbon steel, mild steel, stainless steel, steel alloys, and aluminum.