Industrial Laser Etching: Three Methods

Minuscule laser diodes are used for CD players, LaserJet printers, and telephone communications. Hundreds of thousands of helium-neon lasers are used for UPC barcode scanning in stores and supermarkets.

Lasers are the basis for advanced military range finders and missile guidance systems. Large, multi-kilowatt carbon dioxide (CO2) lasers are used to cut and weld automotive frames and body panels. The list goes on and continues to grow.

Almost every type of commercially accessible laser has found an application in manufacturing. Diode lasers, helium-neon lasers, ion lasers, excimer lasers, helium-cadmium lasers, carbon dioxide lasers and the differing solid-state lasers have all been incorporated in to the manufacturing process.

Of the different range of lasers and laser applications, the largest utilization of solid-state Nd:YAG (Neodymium: Yttrium Aluminum Garnet) lasers is for laser marking.

The notoriety of laser etching is primarily the result of its three most popular process features - the permanence of the mark, the high speed of the etching process, and the speed at which image can be altered. These three attributes most differentiate beam-steered laser engraving from all other engraving technologies.

Applications

Depending on the material, a contrasting mark can be created using any one of three dissimilar methods. Each method is differentiated by the maximum temperature achieved on the material surface.

Surface Annealing

Comparatively low temperatures can be applied to metallic's to anneal the surface. The engraving beam will produce a sharp, contrasting line to the nearby material with a very shallow material penetration.

Etching by annealing has the advantage of not disrupting the surface which is considerable for medical applications, particularly implantable devices. The disadvantage is that, because the process relies on heat conducting into the material, beam velocity must be held comparably slow.

Surface Melting

As an alternative, the material can be brought to a molten state. This method is seldom used with metallics as it offers no advantages. It is regularly employed to bring forth a color change in plastics. A choice of commercial plastics yield excellent color contrast and high quality marking images.

Although the process also relies on conducted heat, the speeds can continually be very reasonable since the process requires less depth than that dictated to anneal metallics. Excellent results are routinely obtained at penetration depths of less than 0.001".

Material Vaporization

The third and most common method is the discarding of material by vaporization. This method has the appreciable advantage of speed. Because the material is almost instantly vaporized with each pulse, the beam speed can be set to the fastest speed achievable which still achieves the desired depth and maintains acceptable pulse overlap.

Multiple-Color Etching

An interesting variation of this 3rd method has been created for the automotive business to produce multicolor etching.

The dashboards of today's automobiles contain a wealth of button-activated controls. Push buttons are employed to control driving lights, interior lights, air conditioning and heating systems, audio systems, windshield wipers as well as on-board computers.

The button caps are molded from a colored, clear plastic and are afterwards painted with a white base coat and a darker, contrasting top coat complementing the composition scheme of the vehicle's interior.

The laser marking system selectively gets rid of the dark top coat to expose the white undercoat creating the desired text and/or graphic legend. The contrast between the two colors provides excellent daytime visibility. For night visibility, the button is backlit to project the composition of the translucent plastic through the marked legend.

Article Source: Free Content Articles Directory

Richard Stevenson is the Sales Director for Control Micro Systems, Inc. a manufacturer of beam-steered laser etching systems. He has published and presented numerous technological papers and articles on laser etching in trade publications. For information on Laser Engraving call 407-679-9716

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