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Encyclopedia > Laser beam welding

Laser beam welding is a technique in manufacturing whereby two or more pieces of material (usually metal) are joined by together through use of a laser beam. This article needs to be cleaned up to conform to a higher standard of quality. ... Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily forms ions (cations) and has metallic bonds, and metals are sometimes described as a lattice of positive ions (cations) in a cloud of electrons. ... The range of sizes in which lasers exist is immense, extending from microscopic diode lasers (top) to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion. ...


The laser beam is a coherent (single phase) light of a single wavelength (monochromatic). The laser beam has low beam divergence and high energy content and thus will create heat when it strikes a surface. The wavelength is the distance between repeating units of a wave pattern. ...


Lasers are utilized in metalworking for:

  • Seam tracking and inspection
  • Surface heat treating
  • Welding
  • Cutting (metallic and non-metallic materials)

Contents

Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. ...


Laser types

There are two primary types of lasers used in welding and cutting:

Carbon dioxide lasers use a mixture of high purity carbon dioxide with helium and nitrogen as the lasing medium. Here are some of the key characteristics for CO2 lasers: The gas laser is a kind of laser in which some sort of gas (such as helium or neon) is discharged to produce the laser light. ... A solid-state laser is a laser that uses a gain medium that is a solid, rather than a liquid such as dye lasers or a gas such as gas lasers. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... This article does not cite its references or sources. ... A laser system generally consists of three important parts: An energy source (usually referred to as the pump or pump source); A gain medium or laser medium; A mirror, or system of mirrors, forming an optical resonator. ...

  • Infrared (10.6 micrometres)
  • Beam transmission by mirror only (not fibre optic)
  • Cutting lasers are typically from 0.5 to 10 kW
  • Difficulties in cutting/welding reflective materials (e.g., aluminum or copper)
  • Can cut non-metallic materials
  • High cutting speed possible

Nd:YAG lasers use a solid bar of yttrium aluminum garnet doped with neodymium as the lasing medium. Here are some of the key charateristics for Nd:YAG lasers: Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of microwave radiation. ... A micrometre (American spelling: micrometer), symbol µm, is an SI unit of length. ... Fiber Optic strands An optical fiber in American English or fibre in British English is a transparent thin fiber for transmitting light. ... Aluminum is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air. ... General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance metallic brown Atomic mass 63. ... General Name, Symbol, Number yttrium, Y, 39 Chemical series transition metals Group, Period, Block 3, 5, d Appearance silvery white Atomic mass 88. ... The Garnet group of minerals show crystals with a habit of rhombic dodecahedrons and trapezohedrons. ... General Name, Symbol, Number neodymium, Nd, 60 Chemical series lanthanides Group, Period, Block ?, 6, f Appearance silvery white, yellowish tinge Atomic mass 144. ...

  • Infrared (1.06 micrometres)
  • Beam transmission by optical fiber possible
  • Available to 2 kW
  • Wavelength absorbed well by metallic materials (including Al and Cu)
  • Not suitable for cutting non-metallic materials
  • Good for fine work, but cutting speeds are generally lower than CO2

Both CO2 and Nd:YAG lasers can operate in either continuous or pulsed operating modes.


Laser beam welding (LBW)

Nd:YAG lasers are being more commonly utilized in automotive parts manufacturing using robotic delivery. CO2 laser welding using a 10 kW system can produce a single pass autogenous weld in ¾” thick stainless steel at 20 ipm (8 mm/s). Systems producing up to 25 kW have been built. Keyhole welding,is a method of laser welding in which a high power continuous-wave laser is focused on the metal to be welded, forming a pocket of ionized metalic gas. This vapor absorbs the laser energy more effectively than the solid material and transfers the heat outward radially from the keyhole, forming a molten region surrounding the vapor.As the beam moves across the work-piece the keyhole is filled in with molten material and solidifies to form a weld. A humanoid robot playing a trumpet In practical usage, a robot is a mechanical device which can perform complex tasks either according to direct human control, partial control with human supervision, or autonomously (that is, fully under computer control). ...


Laser beam cutting (LBC)

CO2 Lasers are most popular for 2D profile cutting of steel plates up to ~3/4” thick (1/2” for stainless, 3/8” for aluminum). Approximate CO2 laser cutting speeds for steel of different thicknesses: The old steel cable of a colliery winding tower Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ...

  • 350 ipm (0.15 m/s) - 20 gauge (0.95 mm)
  • 100 ipm (0.04 m/s) - 1⁄4 in (6.4 mm) thick
  • 35 ipm (0.015 m/s) - 5⁄8 in (15.9 mm) thick

Nd:YAG systems are more common on thinner gauge materials using robotic delivery systems.


Assist gases are used to help expel the molten metal, protect the lenses, and in the case of oxygen on steels—to provide chemical cutting action. General Name, Symbol, Number oxygen, O, 8 Chemical series Chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ...


See also

  • American Welding Society, Welding Handbook, Volume 2 (8th Ed.)


Metalworking
Welding
  Arc welding: Shielded metal (MMA) | Gas metal (MIG) | Flux-cored | Submerged | Gas tungsten (TIG) | Plasma  
  Other processes: Oxyfuel | Resistance | Spot | Forge | Ultrasonic | Electron beam | Laser beam  
  Equipment: Power supply | Electrode | Shielding gas | Robot  
  Related: Heat-affected zone | Weldability | Residual stress | Arc eye | Underwater welding  
  See also: Brazing | Soldering | Metalworking | Fabrication | Casting | Machining | Metallurgy | Jewelry  

  Results from FactBites:
 
Application Experiences with Laser Beam Welding (1489 words)
Laser beam welding is a fusion joining process that uses the energy from a laser beam to melt and subsequently crystallize a metal, resulting in a bond between parts.
Specific laser beam welding features, such as high welding speed, small heat-affected zone, and low material exposure at elevated temperatures are beneficial for welding this type of steel, because prolonged periods at high temperatures may lead to chromium precipitation on grain boundaries and reduction of corrosion resistance.
Laser welding is considered superior because of its typical short welding cycle, which causes little or no evaporation of the alloying elements.
American Welding Society - Welding Journal (2708 words)
Laser welding not only requires high laser power but also a high-quality beam to obtain the desired "deep-weld effect." The resulting high beam quality can be exploited either to obtain a smaller focus diameter or a larger focal distance.
When the laser beam hits the surface of the material, the spot is heated up to vaporization temperature and a vapor cavity is formed in the weld metal due to the escaping metal vapor.
Laser-hybrid welding is a new technology that offers synergies for wide fields of application in the automotive industry, especially where it is not possible or financially viable to achieve the component tolerances required for laser beam welding.
  More results at FactBites »


 

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