Mainstream CAD plus high-speed CNC speeds production of tools and prototype products.

When most OEMs hear the term rapid prototyping, they envision models made from stereolithography, fused deposition modeling, or 3-D printing. These physical facsimiles emulate the characteristics of a finished part, but are not typically molded in production materials. In fact, RP materials tend to be limited, and often do not have properties similar to the final part. For instance, SLA parts may be too fragile for rigorous physical testing.

Of course, most engineers would prefer to access the hundreds of types of resins available for injection molding if it weren’t for the time and cost required to produce prototype tooling. Historically, the main advantages of using traditional rapid prototyping techniques are cost and time savings, because creating production-material prototypes or producing small lots of finished parts was too expensive and time consuming to fit within the critical product development cycle.

CAD and CNC to the Rescue
With the advent of affordable 3-D CAD systems and high-speed CNC equipment, however, one Minnesota-based company has been able to create a new “rapid injection molding” paradigm in which the production of real injection molded prototypes and small runs of finished parts has become both fast and affordable.

Protomold was founded in 1999 with the mission of making fast, affordable injection molded parts a reality. Leveraging the benefits of 3-D solid modeling technology and its own moldmaking and injection molding expertise, the company is well on its way to achieving that goal. According to Protomold CEO Brad Cleveland, the company has doubled in size each year and now operates eight CNC mills and 10 molding machines with up to 200 tons capacity in its 30,000-sq-ft facility.

“There is no substitute for a real injection molded part, especially for prototyping,” Cleveland explains. “Most conventional injection molding companies focus on high-volume production to amortize high tooling costs across hundreds of thousands or millions of parts. Using our proprietary process, we’ve dramatically lowered tooling costs and routinely ship prototype parts in about a third of the time—sometimes as fast as eight hours—and at a third of the conventional injection molding price. We do this by using a highly automated system that includes cutting-edge CNC equipment and 3-D solid modeling.”

According to Cleveland, 3-D solid modeling technology has allowed Protomold to streamline the entire process, enabling the company to pass these savings on to customers. In fact, it is such an important part of the “Protomold Process” that the company does not accept 2-D design data as input.

Protomold uses SolidWorks software as its in-house solid modeling package because it provides the fastest, most affordable means for handling customer designs. “The software can read a multitude of CAD formats and produces the clean, accurate models that are such an important part of our process,” Cleveland says. “We use the software to address file format and geometry issues, such as adding missing faces and vertices or tweaking the customer’s model to add draft or adjust wall thickness.”

From the Founder
Former self-professed computer geek Larry Lukis founded Protomold after realizing how difficult it was to get production-quality prototype parts. He was running a company called ColorSpan, an OEM that produces printers and desktop publishing systems, and found that the lead time for molded parts was putting a major kink in the product development cycle.

Today, Lukis is the chief technology officer of Protomold, and he explains the company’s niche in this way: “We don’t aspire to address true high-volume production tooling. We’ve learned enough to know that these tools can be works of art, and we definitely don’t do art. When a tool is going to make a million parts, what’s it worth if the tool can run a cycle every 12 seconds instead of 15? Plenty! That’s why a lot of high-tech design effort goes into these molds, and that’s the way it should be.”

Lukis asserts, however, that for prototype and low- to moderate-volume tooling, there is room to drastically reduce both lead time and cost. “In ballpark terms, we can deliver real injection molded parts in as little as five days and at a price starting under $2000,” he says.

Protomold has automated the process of making injection mold tooling for relatively simple parts. “Simple” means that it is moldable in a straight pull mold with no side actions, and the part geometry can be machined. The company works exclusively with high-speed CNC machining in aluminum. “No steel, no EDM, and none of the costly and time-consuming custom engineering that normally goes into the development of injection mold tooling,” Lukis adds. Once prototype parts are tested and approved, customers immediately have bridge tooling available to build up to 10,000 parts for marketing or pilot production.

A Case in Point
Work that Protomold did for Pakon Inc., the largest U.S. supplier of photographic slide mounts and mounting equipment, is an example of the rapid tooling and molding system in action. Pakon’s Impak Div. manufactures some of the world’s fastest digital film scanners, and last year, one of its newest models had a problem.

Pakon began in-store trials for this model, a scanner used to produce Kodak Photo CDs. During the trials, 35-mm film was projecting out of the machine into walkways or falling on the floor, scratching consumers’ irreplaceable negatives. Evaluation of the situation identified the need for a deflector to direct scanned 35-mm film into a take-up bucket.

“The challenge was to complete the design, prototyping, and manufacture of the deflectors with sufficient quality to meet the functional requirements in time to support Pakon’s production schedule,” Crystal recalls. “Because both Pakon and Protomold use SolidWorks software, we were able to use rapid injection molding to produce 60 deflectors from the native SolidWorks file in less than two weeks. After that first run proved successful, we produced a total of 800 deflectors to meet Pakon’s pressing need.”