Appliance Design - October 2007 - (Page 40)

PROTOTYPING A fan blade made from SLA by Met-L-Flo undergoes quality control. An example of a successful low volume production run, these parts were made by Met-L-Flo in quantities of 150 sets. While many of the rapid tooling methods use additive processes, Protomold makes aluminum molds by using fast-moving CNC machines in a process it calls rapid-injection molding. One of the benefits of rapid injection molding, says Cleveland, is the ability to use any off the shelf plastic material. Speed is another benefit. According to Cleveland, rapid injection molding can economically deliver from 25 to 10,000 molded prototypes in one to 15 days. He adds that design engineers can upload the 3D CAD model of the part and if the part can be made with Protomold’s technology, milling of the mold components can literally begin within minutes. The fast turnaround time is a result of the speed of the CNC machines to create the molds, which Cleveland says far outstrips the speed of additive technologies to tool building. However, rapid prototyping machines can generate more complex parts than can CNC milling methods, though Cleveland adds that, as software and CNC machining technology improve, more complex parts can be built. In effect, the speed of this technology is a trade-off in terms of the complexity of the part that can be built. The design engineer must decide as to whether the technology is right for that application and if the trade off is worth it. The same can be said for most of the methods available to designers. Rapid tooling and rapid injection molding allows for production to ramp-up faster. With 40 applianceDESIGN October 2007 both methods, tools can be made in hours or days, as compared to the weeks and months for a traditional injection-molding tool, and costs are significantly less. According to the engineering Web site, efunda (www.efunda. com), time to first article is 20 percent faster than that of conventional tooling, and the tooling cost is less than five percent of conventional tooling costs. The life of the mold is limited, however, by the softness of the aluminum. Over time, the molds will degrade and lose tolerance, especially if the plastic resin is a tougher material such as glass-filled nylon. Still, unlike rapid prototyping technologies that make parts one at a time, molds developed through rapid tooling and rapid injection molding can produce up to tens of thousands of production parts. If larger part volumes are needed, then traditional injection molding using hard tooling is most likely the better solution. However, while waiting for the hard tools to be created, the rapid tooling and rapid injection molding technologies can “bridge” the time gap and begin to make production parts and get the product to market faster. In some cases, the tooling can serve as more than just a bridge, says John Budreau, director of new business development for PTI Engineered Plastics of Clinton Township, Mich. The tooling the company develops for prototyping can be used to produce as many as 150,000 production parts. Being able to utilize the prototype tool for production speeds along the process. In one application, a medical device manufacturer approached PTI with a complex device that featured seven molded plastic parts, three of which were insert-molded and four of which required decorating. The company wanted to go into a clinical study within three months. PTI developed the tooling for the prototype, which was approved, and was able to produce 15,000 components using the same prototype tool by the deadline. In the 12 months that followed, the same prototype-to-production tool was used to produce another 10,000 parts a month. The rule of thumb in terms of part volume versus technology used is that if only a handful of prototypes are needed, then one of the many rapid prototyping technologies may be employed. For short runs of production parts — ranging from the hundreds to 100,000 parts or more — than rapid tooling or rapid injection molding might be a logical choice. < For more information, enter numbers: Met-L-Flo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .316 Or email: carl.dekker@met-l-flo.com Phillips Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317 Or email: info@phillipsplastics.com Protomold/First Cut Prototyping. . . . . . . . . . . . . . . . .318 Or email: info@protomold.com PTI Engineered Plastics . . . . . . . . . . . . . . . . . . . . . . .319 Or email: pti@teampti.com www.applianceDESIGN.com http://www.efunda.com http://www.efunda.com http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - October 2007

Contents Editorial Shipments/Forecasts News Watch Applying Powder Coatings to Plastic Parts is No Longer a Pipe Dream New Technology Platform Provides the Ability for a single IC to Control Two- Motors in a Single Appliance, Simplifying Motor Control Design Advanced Motor-Control Techniques have Become More Accessible to a Wider Array of Appliances, Helping to Improve Efficiency and Reduce Noise Adding USB Host Capability to Appliances Permits In-Field Programming and Acquisition of Test Data ZigBee Modules Make it Easier to Design Wireless Connectivity into Applications New Concepts such as Rapid Tooling and Rapid Injection Molding Provide Stepping Stones Between Prototyping and Full Scale Production A Number of Factors and New Developments Affect the Decision on Whether to Build Prototypes In-House or Outsource to a Service Bureau DesignMart Advertiser’s Index Association Report: CEA

Appliance Design - October 2007

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