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June 20, 2002

5 Min Read
Special effects rely on teamwork

thumper.jpg

Designing and producing a special effects resin housing for the Variable Power Thumper Massager required a close relationship between OEM, molder, and color supplier.

Designers are reaching higher and farther these days to differentiate their products in an effort to stand out from the competition. Special effects resins are one way this can be accomplished. A recent project involving metallic flake PC illustrates why this design choice requires a close relationship with manufacturing.

Wellness Innovations' flagship product, the Thumper Professional Massager, had served chiropractors and individuals worldwide as an effective, dependable workhorse for 15 years. When the company developed a new version of the Thumper with additional features, Canadian injection molder Performance Plastics asked supplier Clariant Masterbatches to develop an elegant, special effect color that would give a sleek, new appearance to the massager's tough PC housing.

Wellness Innovations, founded 17 years ago by chiropractor Edward Noble, M.D., supplies chiropractors, massage therapists, sports trainers, and professional athletes with several models of professional-quality, heavy-duty massagers. The new Variable Power Thumper Massager needed a distinct look to differentiate it from the earlier model, many of which still provide dependable service after 15 years of use.

"The older unit is a bone-white color, and Dr. Noble wanted something new for this product that would impress our customers," says Edmond Lau, production manager for Wellness Innovations, which has a manufacturing facility in Markham, ON and a sales and service center in California. "In choosing the color, we looked at several selections, including a blue and a black with a silver metal flake effect. They all looked great but, in fact, the graphite with silver sparkles was the best for the new unit."

With its expertise in engineering resins, Performance Plastics wasn't afraid to tackle a special effects colorant in an already challenging base polymer for the two-piece housing. "We're used to filling needs in specialized areas. After all, we're a custom molder," says Lou Coppa, president of Performance Plastics.

Performance Plastics is located in Toronto, ON. The 19,000-sq-ft facility produces 100 different products with presses that range from 80 to 320 tons. Its 25 employees also provide customers with additional processes such as hot stamping, sonic welding, screen printing, and assembly. "Our strategy is to be a partner with our customer, to provide as much of a turnkey operation as we can," Coppa says. "Where it's justified, we'll even set up a separate line, and we can ship right to the distributor or outlet."

Coppa says that in keeping with this philosophy, Performance Plastics wanted Wellness Innovations' color change to be as easy as possible. "Clariant supplied us with several different colors for Wellness Innovations to evaluate, and the graphite with silver specks was a perfect fit with the product design."

The high-tolerance housing parts are run on a Mitsubishi 320 press with a masterbatch let-down ratio of 4 percent. Says Coppa, "We had to make some changes in how we ran the part. The screw design was particularly important to get the right effect. A low-compression screw should be used with polycarbonate in general, but even more so with the metal fleck because it tends to plasticate more evenly. You have less shear and more even distribution of particles. By its nature, the particle distribution is random, but with the proper process they are spread evenly. Even though we want a degree of uniformity, one of the beauties of working with this kind of special effect is that each unit is unique, almost personalized."

Maintaining the proper heat is important to prevent the particles from accumulating in the weldlines. "One of the drawbacks to working with this type of special effect is that you can get buildup," Coppa says, "but that was easily handled by lowering the screw speed and the injection rate because of the way these molds are gated." Each part has two gates of .060 by .060 inch, which is quite small for polycarbonate. The total weight of both parts is 672g.

"A lot of our competitors do not have the required technology to work with engineering resins like polycarbonate," says Gary Mercer, Clariant sales representative. "Our ability to produce color masterbatches for multiple resin groups at our Mississauga, ON site enabled us to meet Performance Plastics' requirements. We're constantly on the lookout for difficult applications that have a market."

For the massager, Mercer says Clariant developed a masterbatch with a silver-coated fiber to produce the metal flake effect. "Processing the fiber into the polycarbonate is tricky," he says. "One of the challenges is to maintain particle size because polycarbonate is such a stiff resin, but with our formulation expertise and Performance Plastics' processing experience, the project has gone very well."

Clariant also secured the UL approvals for the unit. Because of the metal-coated fiber, the material had to pass UL's stringent testing for spark and discharge. With the approval process complete, Wellness Innovations will soon begin shipping the new massagers, which feature a variable-speed control and are powered by a high-torque permanent magnet d-c motor. Lau says, "Although the unit has not yet been released, we have shown the test units to our customers, and they all like it as much as we do."


Contact information
Clariant Masterbatches Div.
Charlotte, NC
Juli Williams; (704) 331-7154
www.clariant.masterbatches.com
[email protected]

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