Plastic Fantastic

Time is money, so prototype for profit

Rapid prototyping can reduce the number of costly engineering changes made to a mold, cut the time-to-market for a new product, and—with the development of new RP systems and materials—even fill the gap between prototype and low-volume processing.

Mack Prototype Inc. provides a variety of RP/RM services that help give the company an edge with customers on major, multi-mold programs.

Developments in rapid prototyping (RP) have gotten to the point that firms such as Quickparts Inc. (Atlanta, GA) are gaining more notice, and more competition. As its name implies, Quickparts can supply parts, quickly, using CAD models to form parts via a number of RP methods. Patrick Hunter, VP of sales and marketing at Quickparts, notes, “The continual evolution of materials has pushed prototyping into the mainstream as a technology. It allows designers to have greater design freedom: they’re not as limited in their design, especially with respect to SLS (Selective Laser Sintering), which many customers are choosing for actual end-use parts.”

Rapid prototyping is no longer confined to just prototyping. Terry Wohlers, publisher of the “Wohlers Report 2007,” a 220-page global study on advances in this field, points out that RP also entails rapid manufacturing (RM), which can cover a number of “fast processes” including rapid tooling (RT), the speedy manufacturing of mold or tooling. It also encompasses the new moniker ‘additive fabrication’ (AF), which has developed into three basic categories: 3D printing for product design and concept modeling with machines such as those manufactured by 3D Systems, Z Corp. and others; mid-range systems for fit-and-function applications and master patterns; and high-end systems for the rapid manufacture of custom and short-run production parts, using machinery such as that produced by EOS.

Quickparts’ new QuickARC division produces model prototypes for builders and architects to enhance visualization.

New materials are cropping up with regularity, mimicking plastics of all sorts: polyamide (PA, neat or filled with glass, aluminum, or carbon fibers); PS, ABS, PC, PC-ABS, and polyphenylsulfone, plus a growing family of photopolymers (mostly epoxies and acrylates).

Wohlers projects that the next frontier for rapid technology is applying it to the “actual manufacture of end-use parts,” or RM. “Considering the array of possibilities, the market potential is enormous,” Wohlers states. “However it will take years to develop. In the meantime, compelling examples of RM will stimulate the development of the next generation of systems. These machines will eventually affect a wide range of industries and applications around the world. Product ideas that were once impractical due to tooling and other costs will become a reality.”

One of those new machines recently was acquired by Vaupell Rapid Solutions (Hudson, NH). It added Direct Metal Laser Sintering (DMLS) capabilities with the installation of an M 270 DMLS system from EOS of North America Inc., a division of EOS GmbH, based near Munich, Germany. Vaupell plans to produce tooling inserts, prototype parts, and end products directly in metal. “The M 270 will allow many of our customers to more quickly evaluate functional prototypes in actual or close-to-actual end materials, and in design configurations and time frames not possible with any other established process,” explains General Manager Steve Ettelson.

No fooling on lower-cost tooling

One of RP’s biggest advantages is reducing the cost of tooling, primarily by reducing or eliminating engineering changes after the mold is completed. Mack Molding, a processor that specializes in large-parts molding with seven facilities and 120 presses, recognized early on the advantages prototyping could offer a molding company. In 1999, Mack bought Apple Pattern Company Inc. in Gardner, MA and renamed it Mack Prototype Inc. The company offers a full range of product-development services, including engineering analysis and rapid prototyping for both small and large parts, CNC machining and finishing operations, tooling, and small-part injection molding.

Ric Perry, president of Mack Prototype Inc., says one of the goals of RP is making sure that when the moldmakers start cutting steel, they don’t have to make a lot of engineering changes on the back end. “That’s the thing this industry brings to the table more than in the past,” says Perry. “We’re refining the design before cutting steel and going into production. For example, a couple million dollar tooling package might have 10-20% of that cost just in engineering changes; we did a $2 million program with a large number of prototypes at the front end that resulted in no engineering changes.”

“We’ve established some tools for our speed-to-market program, such as having a standard or universal mold base, and only designing the core and cavity, then machining those using CAD,” explains Joe Herold, product development engineer for rapid prototyper Vernay Laboratories Inc. (Yellow Springs, OH). “Ideally we can get the cavities and the material in 10 days or less and have samples. We have a system set up that after we produce samples, we check the samples and make sure they’re functional for full production processing. We do a full-function characterization of the part. The part then goes to the customer for their evaluation. We’re moving toward the Toyota Development System, where we’re actually evaluating multiple material alternatives at the same time in a lean-based system.”

Another speedy tooling option was recently introduced by PTI Engineered Products (Clinton Township, MI), which specializes in functional prototypes. The company in March launched its proprietary P3 (PTI Production Prototype) process, one that creates ready-for-production prototypes using tooling that is also durable enough to mold and support low-volume production qualities—so that, once a prototype is approved, the processor can begin molding saleable parts, crunching time-to-market. PTI is an injection molder with 35 presses sized from 12 to 500 tons, but about 50% of the company’s business is comprised of prototyping and short-run manufacturing. “In one case, we were able to mold about 8-10 different resins with different levels of fillers such as talc and glass, as the customer performed various tests to determine the appropriate material,” says John Budreau, director of new business development for PTI. “Within the same material families you can still mold a variety of materials, even accounting for shrink.

A medical-device OEM needed to bring a 16-piece plastic patient monitoring system to market within six weeks. Its long-term product needs were for low-volume production of 5000 pieces annually over a period of 10 years. PTI’s solution was to design and build 16 different molds using the company’s P3 process (PTI Production Prototype). Each mold was capable of producing more than 100,000 pieces.

Parts’ molding requirements ranged from 75 to 500 tons’ clamp force. Several parts required secondary decorating, pad printing, and texturing on the molds. With the P3 process, in which prototyping and production uses the same tool, the customer realized a cost savings of $150,000 in its initial tooling spend compared to traditional tool methods not required for this low-volume project.