Computer Controlled Light Beams For Accurate Positioning
Material processing equipment has become much more flexible in recent years. CNC sawing and routing equipment can now quickly transform CAD drawings into parts of very complex shape with high accuracy and part-to-part repeatability. Along with this capability comes new challenges: how to precisely locate the part blank to ensure maximum material yield; to position the part holding fixtures where they are guaranteed not to interfere with the cutting tool path and to do it all quickly so as to maximize the productivity of your CNC investment.

For years, straight line sawing applications have benefited from the use of Laser Guide Line Lights to provide a reference for material positioning. By producing a bright red, highly visible straight line on the surface of the material being cut, the laser allows the machine operator to visualize the path of the saw blade prior to cutting. Recent advances in technology now permit this same benefit to be extended to much more complex shapes.

Products known as 2D Laser Projection Systems combine the same source of bright laser light with a series of computer controlled mirrors in such a way that a dot of light can be raced around a pattern of curves or lines rapidly enough for the entire pattern to appear as a solid, single image. The same CAD data which directs the CNC machining can be used to visualize the entire part shape along with hold down fixture locations prior to beginning the machining cycle.

This means that fixtures and clamps can be quickly located with absolute assurance they won’t interfere with or damage expensive router heads and cutting tools, thus avoiding the wasteful downtime and high replacement costs created by such damage. Part blanks can be positioned accurately for best material yield. Operators can be guaranteed they’ve selected the right blank for the part in process. Even irregularly shaped blanks or scrap material left over from previous operations can be utilized effectively to help minimize waste of expensive materials. Depending on the application and the materials used, these factors often result in overall improvements in process efficiency from 30 to 50%.

In addition, these systems are also used to reposition components for subsequent machining steps or for locating parts within assembly operations. Nesting of multiple parts on a single blank becomes easier since all part shapes can be seen in relation to one another before cutting begins. Pre-application of bar-code part labels prior to cutting is now possible with full confidence that no labels will be damaged by the cutter.

Modern 2D Laser Projection Systems typically include Windows-based graphical control software for easy operation and direct, intuitive control of all laser functions. Thanks to recent refinements in software, set up and calibration of these units can be done quickly and easily. The laser projectors typically accept industry standard HPGL and DXF data formats produced directly by commonly used CAD programs. Certain systems even have available software options which allow direct interpretation of many of the types of G-code files used as input by CNC machine controllers. Laser systems are available with traditional red light output, which is suitable for the majority of applications, or with green light output to preserve high visibility even in brightly lit working environments.

In short, for a modest outlay that all but guarantees a rapid return on investment, fabrication plants can now easily integrate into their processes sophisticated laser-based positioning aids that will enhance throughput, reduce the chance of machine damage or operator injury, and dramatically improve both the efficiency of their CNC equipment and their bottom line profit.

Written by Terry Camp, Vice President and Chief Engineer at Carter Products Company, Inc. Carter has produced Laser Lighting products for alignment applications since the 1970s. They have recently partnered with Z-Laser, Eur-ope’s leading supplier of precision laser products, and now offer a complete selection of Guide Line Lasers including the Model CPS 2D Laser Projection System.