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Acuity brands' light idea: through Acuity Brands' partnership with its in-house casting facility, a rapid tooling method was developed that illustrates how the lighting manufacturer stays at the top of its market.

The ornamental street lamps and light poles lining your local main street may look like they are from a bygone era, but they were probably installed more recently than you would expect and might even contain modern LED lights. There's also a good chance they were made by Acuity Brands, Atlanta, one of the largest lighting manufacturers in the U.S. and a user of a significant amount of castings.

The lamps may look antique, but Acuity Brands, which posted net sales of more than $1.9 billion in fiscal year 2012, uses modern methods to produce its lamps, including a rapid tooling technique that has helped the company shave weeks off of its leadtime for product launches. A brainchild of Acuity Brands senior design engineer Robert Davis, the technique gives the company an edge in designing and producing custom lamps for municipalities, businesses and universities.

Acuity Brands Atlanta, Ga.

Industry:    Luminaires, lighting control systems and related products.

Revenue:     More than $1.9 billion in fiscal year 2012.

Brands:      Lithonia Lighting, Acculamp, American Electric Lighting,
             Antique Street Lamps, Carandini, Gotham, Healthcare
             Lighting, Holophane, Hydrel, Mark Architectural
             Lighting, Peerless, Reloc, Tersen, Winona, DTL,
             Lighting Control Sc Design, Roam, Sensor
             Switch, Synergy and Sunoptics.

Employees:   Approximately 6,000.

"Standard industry lead time is eight to 10 weeks," Davis said. "When you go out to bid a custom project, with no tooling cost and no leadtime, it's a big advantage. That's what we are stocking on and winning quite a bit on."

Acuity's path to industry-leading delivery times on new, custom projects started eight years ago with the spark of an idea from Davis, a designer with just about a year of casting experience under his belt.

Light Bulb Moment

In 2003, Acuity had an order with Key West, Fla., that included making custom door pulls with its town logo. Customization is nothing new in the outdoor architecture industry. According to Davis, most towns want the antique look with their own twist to give it an identity In the past, a rubber mold with the design addition--like a logo--was glued to the tool and then cast. The rubber mold wore out quickly. Davis felt there was a better way to make custom products quickly and thought an ABS plastic 3-D printer could be the key.

"I am always looking at different technologies and ways to try to improve products and processes for Acuity Brands," Davis said. "Don't get locked in by what you know to be feasible."

Davis' vision was helped by Acuity Brand's metalcasting facility asset in Matamoros, Mexico. The lighting manufacturer, which produces products under several different brands, purchases castings from around the world. It also owns and operates the sand and permanent mold casting facility in Mexico. It is there that Davis learned the ins and outs of casting and tested his rapid tooling idea.

"When I came to Acuity, all the welding and machining was second nature to me, but it was the first time I played with castings," he said. "I went to our facility in Matamoros to see what casting is first hand and was trained pretty quickly."

When Davis first broached the idea of using the 3D printer to produce tooling at the Matamoros casting facility, it was met with apprehension.

"The biggest challenge was to deliver a smooth surface to the ABS plastic part," said Javiar Garza, a casting engineer at the Matamoros facility.

After a few attempts, it was clear the plastic pattern was not providing the desired results. Garza suggested using the printer to make a pattern for the tool, including matchplate, which the metalcasting facility then polishes to achieve the required surface finish.

"It was great, because normally it takes three to five weeks to develop a new pattern," Garza said. "With this method we lowered the leadtime to no more than 1.5 weeks."

Acuity designers draw the part, whether it is adding a logo to an existing design or creating a completely different style, in 3D and scale it in the model based off pattern shrinkage, which is an allowance made on patterns to compensate for the change in dimensions as the solidified casting cools in the mold.

"I consult with the factory in Matamoros because shrink is not linear," Davis said. "I rely on their knowledge and expertise to guide us."

Acuity scales the model for two shrink sizes since the plastic pattern will be used to cast the tool, which will then cast the part.

"The first aluminum part we get off the plastic tool is one shrink big, and that becomes the tool for production," Davis said. "We take the ABS plastic pattern and label it master."

When a new tool is needed for an existing product, the casting facility makes it from the master ABS plastic pattern.

"We go to the shelf, use the master and an hour later, we have a brand new tool," Davis said. "There is no downtime."

If the required pattern is too big for the printer envelope, the model may be produced in sections and assembled together to make the finished pattern. Davis used this method to produce a custom scroll measuring 3 x 5 ft. Since the first 3D printer, Acuity also has added a couple more machines to its model shop to accommodate larger parts and the increased usage of the rapid tooling method.

"After I got my printer, of course every brand wanted one," Davis said.

The rapid tooling method is more than a time saver.

"For every custom opportunity, new tooling is required. Who's going to absorb that?" Davis said. "A lot of times we would do it ourselves to get the job for the payoffs later. [With the new method] the tooling cost went from the standard $10,000 to basically the cost of the plastic."

Illuminating In-House Casting

The choice between sand or permanent mold casting depends on the design, Davis said. Some design elements are less expensive and easier to achieve in sand casting, where mold aids such as floating inserts can be used. Historic designs based on the early 1900s often feature surface finishes that are not as smooth and thicker, heavier elements that are more cost effectively produced in sand casting. But permanent mold offers better dimensional accuracy and is more cost effective for larger volumes.

Acuity works with several casting sources, including a vendor in Saltillo, Mexico, to procure cast iron components.

"We determine our source based on tooling cost and lead time cost," Davis said. The tooling engineer works with Acuity's central sourcing group to make the decision. The role of Acuity's in-house metal-casting facility in the production of rapid custom jobs has made it a more frequent choice.

"When I came to corporate headquarters in Georgia, some of our people didn't know we had a metal-casting facility," Davis said. "Now that they do, a lot of tools and processes have been migrated down to Matamoros. It makes more sense to feed ourselves, if you will."

The casting facility might have been a little known secret at Acuity Brands 10 years ago, but its existence helped kick off Davis' rapid tooling idea into fruition within six months.

"We are definitely ahead of the game, and we rely a lot on our foundry," Davis said. He believes it would have taken considerably longer working with an outside vendor.

"I am sure this was disruptive to the casting supplier because it's different," Davis. "Could it have been done [with an outside supplied? Yes, but not in a comfortable amount of time."

With work picking up, the facility in Matamoros has acquired three new CNC machines in the last three years. Acuity also is considering adding diecasting to the sand and permanent mold casting processes in Matamoros for higher volume production.

"[The workers at Matamoros] see the factory as finally growing up," Davis said.


For an audiocast with Robert Davis, design engineer for Acuity Brands, go to

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Author:Wetzel, Shannon
Publication:Modern Casting
Geographic Code:1MEX
Date:Feb 1, 2013
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