Laser Machine Tool Improves Sign and Display Fabrication


The Coherent OMNIBEAM is a compact, self contained system for cutting a wide range of materials.

March 03, 2013

Indoor signs for office buildings and other commercial structures are often produced by cutting out small letters or other shapes from acrylic sheets, and then affixing these cut pieces to a sign board with adhesive. Unfortunately, the traditional mechanical methods for performing this cutting have some drawbacks. But now, a new generation of CO2 laser based machining systems delivers the desired cost and quality characteristics to make them an attractive alternative for many sign makers.

Acrylic Cutting Background
Most acrylic cutting in the sign industry today is still performed with the mechanical router. Probably the most significant drawback of this method that router cutting produces a rough edge, which must then be subsequently buffed or flame polished in order to give it a smooth, transparent appearance. Also, a router cannot produce sharp corners and render intricate detail. On the other hand, the router is simple to implement, and requires very little operator knowledge.

Abrasive water jet cutting is also used by some sign makers to cut acrylic. These have the ability to cut sharp corners. Unfortunately, water jet cutting produces a frosted edge that requires additional processing for applications in which a polished finish is required. The other major negatives of water jets are their high capital cost, the ongoing expense of abrasives, and their relatively slow cutting speed.

In contrast, the CO2 laser is in many ways an ideal tool for acrylic cutting. Its infrared output is strongly absorbed by acrylics (even those which appear transparent in the visible), enabling it to rapidly cut by essentially melting and vaporizing away material. And CO2 laser cutting overcomes the main disadvantages of both mechanical and water jet processes. First, laser processing can deliver a variety of cut edge finishes, including a smooth, transparent edge which entirely eliminates any post processing. Also, laser cutting is substantially faster than other methods, especially when the time required for other post processing steps is included. Moreover, the focused laser beam produces a very narrow cut width (as small as 150 µm), thus allowing the production of very sharp edges and angles, and fine features. Plus CO2 laser based tools are flexible, and can perform anything from kiss cutting to through cutting, with very accurate control of cut depth and high repeatability, without the need to change tools. Furthermore, laser cutting can be employed on materials over a wide range of thicknesses, from mylar sheets to 25 mm acrylic. And lastly, because the laser is a non-contact tool, there is no tool wear, which results in very consistent results.

Acrylic can be readily cut with a polished edge appearance using the OMNIBEAM.

Practical Laser Systems
The Coherent OMNIBEAM laser machining center exemplifies the newest breed of automated tools for laser cutting of plastics (and even thin metals). Several models are available utilizing different Coherent Diamond series CO2 lasers in the 150 W to 400 W range, with higher powers translating directly into faster cutting speeds (over 50 meters/minute at 400 W). The cutting bed of the OMNIBEAM can accept material sheets of up to 1.2 m x 1.2 m, and can process acrylic sheets of up to 25 mm in thickness.

The typical sign making operation is a relatively small shop, in which equipment may be crowded together at close quarters and is often operated by personnel not familiar with lasers. For this reason, the OMNIBEAM is constructed to have a small footprint and is enclosed, so that the operator has no access to laser radiation. Plus, an extraction system completely prevents any cutting fumes from escaping to further enhance safety.

Cutting patterns are createdusing a PC based CAD or drawing program. Up to 10 different processes (rapid cutting for a frosted edge, slow cutting for a polished edge, engraving, etc.) can be specified within a single job by utilizing multiple layers within the original artwork file.

In conclusion, the Coherent Diamond laser based OMNIBEAM machining system can cut a variety of materials, including plastics, wood, natural stone, fabrics and metals. This broad capability, combined with its compact size, ease of use, and low cost of ownership characteristics, make it an attractive alternative in sign making as well as many other industries.

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