An outdoor lighting manufacturing has improved the appearance and functionality of their product by producing CNC prototypes whose higher accuracy makes it possible to refine their product to a higher degree. In the past, Architectural Area Lighting (AAL) produced prototypes of their lighting fixtures with hand tools but this was time-consuming and inaccuracies hindered the design process. So the company purchased a CNC router that produces prototypes from foam that match the computer aided design (CAD) files used to define the part within a few thousands of an inch. The CNC router typically takes only about 12 hours to produce the prototype and runs by itself without requiring operator attention. "Having an accurate prototype makes it possible to evaluate the design to a higher degree and also lets us validate the fit and functionality of the part," said Cory Landefeld, Product Design Manager for AAL. "The new router paid for itself in less than a year by drastically reducing the time and money we spent prototyping."

Architectural Area Lighting is a leading manufacturer of specification grade, outdoor contemporary and traditional style lighting fixtures. The company specializes in combining relevant aesthetic designs with superior lighting performance to ensure the quality of light matches the quality of the fixture. Some of the company’s typical lighting applications include commercial buildings, retail applications, downtown street lighting, educational facilities and sport complexes. AAL’s products include period and contemporary lighting, floodlights, steplights, wall sconces and bollards. The company design, develops and fabricates their products while die castings are produced by subcontractors.

The ability to design stunningly attractive yet highly functional designs is the key to their success. Using Ashlar’s Cobalt CAD software, designers have been producing increasingly sophisticated 3D geometries that have attracted the attention of architects, specifiers, engineers and building owners. The designers typically conceive and tweak their designs by viewing renderings on their computer screen. "But while the latest computer modeling tools provide a very realistic view of a proposed design, there are many important aspects of the design that are difficult or impossible to evaluate on the screen," said Robert Nankil, Product Designer for AAL. Rendering software is good but it can’t perfectly represent the way that an object appears under actual lighting conditions. We wouldn’t think of investing tend of thousands of dollars to build die cast tooling until we were able to review the actual part. We wouldn’t think of going into production without being able to view a prototype under different light conditions, put a bulb in the product to light it up, and place it into a real-world setting so we can see how it looks. Another reason that prototypes are needed is that many different people in the company play a role in evaluating the design and some are not experienced in the sometimes different art of translating from the screen to the real world. There’s also the issue of evaluating how the casting works with the different accessories and making sure that everything fits together just right."

In the past, AAL technicians produced a prototype of the design from foam using a lathe and hand tools. One problem with this approach is that producing a complicated prototype could easily tie up a skilled person for a week. And since the company has switched to the Techno router, their designs have continued to get more and more complex to the point that it would take considerably longer, perhaps up to a month, to produce some of them. Accuracy has always been a critical concern in producing the prototypes because of thin wall thickness. But it was never possible to achieve the desired level of accuracy with hand-built prototypes. "The details just weren’t there which made it difficult to evaluate the designs to the level that we would have liked," said Andy McMillan, Product Designer. "Another problem was that the accuracy wasn’t good enough to assemble the prototype with the accessories to see how everything fit together and worked as an assembly. Because of these problems, there were some cases where we had to make expensive changes to the mold and other cases where we realized after the product came out that we could have made improvements if we had been able to view a more accurate prototype."

The design group jointly came to the conclusion that a more accurate prototyping tool would help them take their product development efforts to the next level. "We considered several different options," Landefeld said. "Stereo lithography had the accuracy we wanted but the machines that were within our price range did not have the envelope that we needed, which is 18 inches by 18 inches. We looked at some CNC machining centers but the machines that were large enough for our parts were very expensive, over $100,000 in most cases. Next, we looked at a couple of CNC routers, machine tools with the flexibility and accuracy of a machining center but which are designed for cutting softer materials such as wood, plastics and foam. We quickly discovered that these machines had the envelope that we need and that the price was in an area that we could afford. Of the two that we considered, the Techno machine was clearly superior in terms of the accuracy it could provide. We also liked the fact that the Techno came as part of a complete package that included all of the software that we needed to get up and running. Finally, the price was right, under $30,000 for the full package."

The Techno machine is constructed on steel stress-relieved bases with hardened steel linear ways. Its shaft-and-bearing system produces very smooth, play-free motion and is an extremely rigid system that produces high-quality cuts. The machine also uses anti-backlash ball screws. These screws have excellent power transmission due to the rolling ball contact between the nut and screws. This type of contact ensures low friction, low wear, and long life. The ball screws also make it possible to produce wooden parts to the machine resolution of 0.0005 inch. Instead of being ball screw-driven, the less expensive machines use rack and pinion gearing, which has too much play to make accurate cuts in small areas. Also this type of gearing wears out quickly in the dusty environment of a carpentry shop. The other main difference we found between the Techno machine and the others was that the Techno uses a servo motor to control cutting motion while other machines use stepper motors, which can give a stair-step cutting effect. With a smoother cut, sanding and finishing time is kept to an absolute minimum.

With the new machine, AAL designers can now produce prototypes that are as accurate as the finished parts while occupying less than an hour of time on the part of the design staff. The designers export the design from Cobalt in the IGES, STL or DXF neutral file format. They then import the file into the Visual Mill software provided with the Techno Router. With this package, it is a relatively simple process to define the surfaces that will be machined and generate tool paths. Normally, the part is completed in two different setups, one machining the inside and the other the outside of the part. Then the operator sets up the part, starts the machine and is free to go back to their job until it is ready for the second setup. The complicated fixtures produced by the AAL typically take about 8 to 12 hours to machine.

When the part is done, the technician removes it from the machine, performs some minor cleanup, paints it and assembles it with other components that make up the complete product, including a light bulb.