This technical information has been contributed by
Brookfield Rapid Solutions

Questions Are the Keys to Successful Prototyping

Steve Ettelson
Brookfield Rapid Solutions
Hudson, New Hampshire

In the rapid prototyping business, we have an enormous number of approaches that can produce the answers needed to make better products and manufacture them more efficiently. The quality of the answer has everything to do with asking the right question. Unfortunately, we don't always know what the right question is, so we simply ask a lot of them. Following are some that we use for openers:

Goals. What do you want to accomplish with the prototype? Check form and fit? Communicate design intent to others who need to know (from toolmakers to marketers)? Smoke out productivity issues before they are replicated endlessly in production? Perform functional testing? Resolve a specific design issue?

After you've built the part, what are you going to do with it? Weld testing? Functional tests? Focus groups? What happens after that? Do you need to get FDA or UL approval? Will you need pre-production parts for test marketing?

Timing. How quickly do you need to turn prototypes around? Could prototyping take longer if it could be overlapped with other product development functions? Would you prototype more extensively if you knew that it could reduce your time to market? How complete does your 3D physical model have to be at a given time to meet specific deadline requirements?

Cost. What quantity of prototypes will you need, and at which stage of the design process? In order to save time and money, what design features can we safely leave out or modify in the model? Can the prototype be made from a different material and by a different process than the one ultimately used in production?

Can materials and processes developed during prototyping be used in production manufacturing to reduce initial manufacturing costs? What answers can we obtain in prototyping to dramatically reduce costs later on?

Synergy. Can you run other product development phases in parallel with rapid prototyping? For example, is it possible to start on tools, fixtures, gaging, or secondary automation? Can we make soft tooling that will bridge the gap between prototyping and full-production manufacturing?

What useful feedback can we get from toolmakers and manufacturing people? What useful information can prototyping feed forward to toolmakers and manufacturing people (e.g., gating schemes and setup parameters)? Have we addressed aspects of the product that will make secondary operations more efficient?

These are the types of questions that can contribute to greater efficiency in the manufacturing of improved products.

The Clean-up Question

If we were smarter prototypers, what question should we have asked you, but didn't? What have we overlooked? The value of not leaving any questions unasked cannot be overestimated.

For example, a rather secretive medical device manufacturer asked us to make a succession of rapid prototypes for the same part. Finally, we prevailed on him to reveal the specific issue that he was trying to resolve. The product function depended on a certain bubble formation as fluid passed through a cavity. One of our project managers, an aeronautical engineer by training, immediately recognized this as a fluid mechanics problem and knew exactly how to solve it. If this question had been on the table for discussion earlier, we could have saved the manufacturer the time and expense associated with many design iterations.

Prototyping is the most paradoxical phase of the product development process. It is where we ultimately "lock in" on product features and manufacturing processes that you will have to live with. But the first thing that prototyping people want to do is ask the customer a lot of questions, which, initially, open more doors than they close. This can be very frustrating, especially when the time-to-market clock is ticking.

However, as prototypers, we need to expand your horizon before we can narrow it in a way that will save you major time and money. Bear with us. As with everything else in rapid prototyping, it all happens very quickly. Favorable results are well worth the time required to answer relevant questions at the outset.

How Questions Focus Prototyping Results

A rapid prototyping shop handles hundreds of projects during the course of a single year. The biggest mistake that it could make is to consider any one of them routine. The ultimate goal is not to build a model but to solve the customer's unique problems. Here are some examples of how probing questions at the outset ensure favorable prototyping end results.

Infrared (IR) Transmissivity. A customer working on a proprietary product needed molded parts with a minimum level of infrared light transparency. The initial recommendation was to mold the parts using prototype injection molds. However, because of the intricate geometric features of the part, prototype molds would have been more expensive than necessary and would have taken more than the time available.

Research into availability of appropriate materials revealed that the parts could be made with DuPont 8120 stereolithography material, and in cast urethane with equally acceptable low infrared transmissivity. Multiple parts manufactured by stereolithography were sufficient to meet the customer's initial deadline. This gave the prototyper time to produce more intricate, cast urethane parts.

Manufacturability issues. Wilderness Mold, a class 101-tool builder, had just five weeks to design and build two-cavity molds for safety goggles. (Under normal circumstances, the job would have taken 14 weeks.) It was absolutely essential that all significant manufacturability issues be detected prior to metal cutting. The prototyper was on alert to begin making a stereolithography model of the part as soon as the preliminary electronic design was available. The essential question here was how quickly the SLA model could become available.

In this case, because the prototyper had been given advanced warning, the model was shipped to the toolmaker within 24 hours of receipt of the CAD file. With the SLA model in hand, the tooling designer quickly resolved a number of critical issues, including the placement of the mold's parting line.

Because the initial design was accurate, manufacturing responsibilities could be divided between Wilderness Mold and its sister company, Brookfield Machine. Also, the molds could be performed flawlessly on the day scheduled for the run-off. Jim Patenaude, President of Wilderness, estimates that rapid prototyping trimmed at least 20% off the turn-around time for this job.

Mechanical vs. dimensional properties. A home products manufacturer needed prototype zinc castings of some intricate parts for mechanical testing. Cost and lead-time were critical issues.

Questioning the customer revealed that only the physical properties of the cast material were essential to the testing. The parts could be made with plaster molds. However, rather than undergo the time and expense of making detailed dimensions in the mold, featureless blanks were cast. The necessary dimensions were then machined into the part to meet the customer's testing, cost, and delivery requirements.

Hitting the street quickly. Geophysical Survey Systems (North Salem, N.H.) had just a few weeks to produce a working model of its Electro-Magnetic Profiling product before an important industry trade show. The show was the year's best opportunity to demonstrate that the company had developed an effective, alternative ground-penetrating radar for detecting underground tanks and piping. The housing for the part, which would eventually be produced by rotational molding, was approximately seven feet long.

The maximum length of stereolithography is about 20 inches, so the model was produced in a number of pieces and bonded using the same UV curable resin used in SLA parts. The bond was cured with a UV light gun and the model was painted. Then it was sent to the manufacturer who populated it with electronics. This was done in time for functional testing of the product and demonstration of the product at the trade show.

In anticipation of orders, the prototyper also proposed that a shrink-adjusted stereolithography model be used instead of a conventional wooden pattern to produce the cast aluminum tooling for rotational molding. This reduced time and gave the toolmaker a more accurate representation of the ultimate part, so that less machining was required on the mold. Rapid prototyping simultaneously addressed the customer's testing, marketing, manufacturability, and time-to-market concerns.

Parallel design and build. Granite Communications (Nashua, N.H.), a manufacturer of hand-held scanners, had an immediate opportunity to sell its newest product design. However, to win the contract, they needed to drop test a functional product within four weeks. The question was how to move from a concept and some industrial design sketches to a functional product in the allotted time.

To meet this deadline, two Brookfield Group companies handled design and tool building as parallel processes. While Brookfield Rapid Solutions was prototyping components and making pre-production tooling for the scanner, Brookfield Machine designed and built the molds for the charger base.

Stereolithography models were used to prove out form and fit, and to test the manufacturability of both the scanner and the base. Injection-molded functional prototypes of the scanner were then produced by Rapid Solutions from rapidly machined aluminum molds.

The prototypes had to be dropped repeatedly on a concrete floor without breaking. For Granite Communications' customer demo, Rapid Solutions also made painted cast urethane models of the charger base, which looked nearly identical to those that would ultimately be manufactured. Once the testing was completed, the prototype aluminum tool was further refined and used to manufacture approximately 10,000 pieces.

By compressing time to market for this product, Granite Communications obtained a functional part with lower cost. The company earned an opportunity to compete by meeting critical deadlines; it also gained a complete solution to its product development process. Although the firm did not win the original bid, Granite Communications had an exceptionally good product ready for market, and subsequently landed a contract from a major OEM.

There are many ways to manufacture prototypes and to integrate rapid prototyping into the design and build process. Generating as many questions as possible at the outset helps the prototyper and the manufacturer develop powerful, comprehensive solutions that pay for the minimal prototyping costs over and over.

Brookfield Group is a fully integrated, one-stop resource for manufacturing services. The firm consists of five specialized companies spanning the disciplines of prototyping, tooling, and production automation equipment. Member companies are Brookfield Rapid Solutions, Hudson, NH; Wilderness Mold, West Hatfield, Mass.; Mill Valley Molding, also of West Hatfield; Brookfield Machine, West Brookfield, Mass.; and Brookfield Innovations, Hudson, NH.

This technical information has been contributed by
Brookfield Rapid Solutions

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