Rotational molders and their trade associations need to reach out to the people who design new products, designer Warren Ginn told industry leaders.
You need to sell your product to the design community, Ginn said during the Society of Plastics Engineers rotomolding conference April 11-13 in Cleveland, which drew about 100 attendees.
Other speakers described designing vertical tanks and a compost bin, and innovative marketing involving cartoon characters.
Ginn, an independent designer in Raleigh, N.C., said he has been a big fan of rotomolding since his early days as a product designer. Unfortunately, for most designers, rotomolding remains pretty obscure. That hurts in today's business environment, when a product's success or failure often depends on how quickly it can be brought to market.
Rotational molding isn't typically considered as often as it should be, when rotomolding could be the perfect fit, he said.
But Ginn said rotomolders needs to stop preaching to the choir and become more outward-focused. He said websites of the two U.S. trade associations the SPE Rotational Molding Division and the Association of Rotational Molders International are targeted toward industry users, not outsiders.
Ginn made several suggestions. The websites need a special designers' page, with videos showing the process and lots of large pictures of parts that highlight details such as kiss-offs and molded-in inserts. Design guides need to be downloadable PDF files, preferably for free. Designers also would appreciate case studies and stories on winners of product design competitions, he said.
You also want to fight the tanks-and-toys perception by showing parts with challenging features like tight radiuses, Ginn said. What about the more premium applications that are pushing the limits of the technology and truly showcase what rotomolding can do?
Ginn also encouraged SPE Rotational Molding Division members to follow the lead of the SPE Thermoforming Division, which has a strong scholarship program and brings sample parts to Industrial Designers Society of America conferences.
Another designer, Michael Paloian, described the creative process. Good designers offer a balance between form and function, he said.
Paloian showed photographs of some classic designs from nature the pattern of seeds on a sunflower plant, a honeycomb and the curved chambers of a nautilus shell. The structure of a bone, with a high-density outer shell surrounding a lower-density core, blends high rigidity with lower weight, like a plastic part made by structural foam molding, said Paloian, president of Integrated Design Systems Inc. of Great Neck, N.Y.
Veteran designer Larry Schneider pointed out that rotomolding machines and molds are much less expensive than molds and machines for injection molding. Another advantage: the same mold can be used to make a part with thinner or thicker walls simply by putting in more or less material.
Schneider Plastics Inc. is in Wadsworth, Ill.
Thomas Moyak described a compost bin he designed under a tight timeline for Sterling Technologies Inc., a rotomolder in Lake City, Pa. Moyak put in only 381/2 total hours to create the Compost Wizard standing bin.
Moyak is a project engineer at the Plastics Technology Center at Penn State Erie's Behrend College in Erie, Pa.
The bin had to compete against low-cost injection molded compost bins, have an attractive appearance and be rugged. To lower shipping costs, it is a two-piece design that is easy to assemble using four simple snap-in connectors, he said.
Moyak described how he came up with the basic design so quickly. His best advice for designers: Take a breather after staring at a computer screen all day. Use your gut and sleep on it, Moyak said. The idea will come to you after you take a break. It always does.
Rotomolders also can take advantage of rapid prototyping, according to Derek Ellis, account manager at Met-L-Flo Inc. of Sugar Grove, Ill. The company makes urethane and silicone molds. We've made a hollow mold within two days, he said.
Met-L-Flo can turn out fast sample parts in a few weeks, for product evaluation, photo shoots and trade shows.
Vince Costello, CEO of Diversified Mold & Castings LLC, said the industry needs cooperation to meet short lead times. To advance our industry, we have to work together designers, molders and mold builders, he said. The later the design changes happen, the more costly it is, the more time it takes to get it to market.
Diversified Mold, based in Warrensville Heights, Ohio, can use several methods to make rotational molds, including cast aluminum, fabricated molds, CNC machining, and model-less tooling. Some molds can be made using more than one process, Costello said.
It's sometimes thinking outside the box, asking, what's going to be most cost effective? he said.
President Robert Dunne described how his firm, Meese Obitron Dunne Co. of Ashtabula, Ohio, markets its bulk containers and rugged carts using a series of dinosaur cartoon characters made out of the rotomolder's products, with names like MODzilla and Recycleosaurus. The company has created histories of the creatures and includes them at trade show booths, in product brochures and in postcards mailed to targeted customers.
Jon Ratzlaff reported that a one-year test of rotomolded water tanks confirmed predictions from finite element analysis done on a computer. Ratzlaff is technical services engineer at Chevron Phillips Chemical Co. LP's technical center in Bartlesville, Okla.
For the physical test, researchers used three 6,617-gallon, high density polyethylene water tanks and filled them with water, plus 10 pounds additional head pressure using water-filled PVC pipes sealed to the top of the tanks. The tanks sat for a year. One result consistent with the FEA report was that radial expansion on the sides of the tanks forced the bottom corner to lift up off the ground, placing a high degree of stress on that area.
One tank, which Ratzlaff said was not made with Chevron Phillips resin, but another company's material) failed with cracks on the top after a year. FEA did not predict that, but he explained the FEA tank design was for a tank with a smooth top, and not with contours like the test tanks.
Ratzlaff said U.S. standards do not mandate finite element analysis to design upright storage tanks, but they should. [FEA] is required in Australia and New Zealand, and I think it should be required in the United States as well, he said.
Ratzlaff said Australia and New Zealand also do not allow tanks to use recycled material and require only compounded-in color no dry blend.
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