Laser Beam Machining (LBM)

Laser technology is being used for a variety of industrial applications, including heat treatment, welding, measurement, as well as scribing, cutting, and drilling (described here). The term laser stands for light amplification by stimulated emission of radiation.A laser is an optical transducer that converts electrical energy into a highly coherent light beam. A laser light beam has several properties that distinguish it from other forms of light. It is monochromatic (theoretically, the light has a single wavelength) and highly collimated (the light rays in the beam are almost perfectly parallel). These properties allow the light generated by a laser to be focused, using conventional optical lenses, onto a tiny spot with resulting high power densities. Depending on the amount of energy contained in the light beam, and its degree of concentration at the spot, the various laser processes identified in the preceding can be accomplished.

Figure 1: Laser Beam Machining

Laser beam machining (LBM) uses the light energy from a laser device for the material removal by vaporization and ablation. The setup for LBM is illustrated in Figure 1. The types of lasers used in LBM are carbon dioxide gas lasers and solid-state lasers. In laser beam machining, the energy of the coherent light beam is concentrated not only optically but also regarding time. The light laser beam is pulsed so that the released energy results in an impulse against the work surface with the melted material evacuating the surface at a high velocity that produces a combination of evaporation and melting.

Laser Beam Machining (LBM) is used to perform various types of drilling, slitting, slotting, scribing, and marking operations. Drilling small diameter holes is possible—down to 0.025mm. For larger holes, above 0.50mm diameter, the laser beam is controlled to cut the outline of the hole. Laser Beam Machining (LBM) is not considered a mass production process, and it is used on thin stock. The range of work materials that can be machined by LBM is virtually unlimited. Ideal properties of the material for LBM include high light energy absorption, reduced reflectivity, low specific heat, low heat of fusion, excellent thermal conductivity, and low heat of vaporization. Of course, no material has this ideal combination of properties.

The actual list of work materials processed by LBM includes ceramics, glass and glass epoxy, plastics, rubber, cloth, wood and metals with high hardness and strength, soft metals.

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