Production tools without prototyping

Prototyping is so ingrained in the injection molding industry that it’s difficult for many designers and moldmakers to envision a product development cycle without it. But a few companies, including design firm Product Development Technologies (PDT) in Lincolnshire, IL, have set out to revolutionize the product development process by eliminating traditional prototype tooling, replacing it with a system that can produce an accurate production mold in as little as four weeks.

"It used to be that tooling was an art, but it has become a science," says Julio Castañeda, a principal in the Ft. Lauderdale, FL division of PDT. "The industry was built by craftsmen, and now teams of engineers and customized software are building more accurate tools faster." With this evolution from art- to engineering-based development, Castañeda believes the plastics industry is entering a new generation—one with a high-tech, 3-D perspective.

Time is Money
The key to reducing product development cycle time, Castañeda says, is to eliminate prototyping as we know it, replacing traditional tooling methods with strategies like SmarTooling, an engineering-driven process developed four years ago at PDT. The philosophy driving SmarTooling says that time spent testing and tweaking prototypes is time added to the overall development process; it's wiser to test and tweak a production unit, instead of prototypes.

A corollary to this also follows. With traditional prototyping, if a design or product fails, an engineer is often hard-pressed to determine if the failure was caused by a design flaw or a fault in the prototype part itself. By performing the analysis up front and verifying the part design before one part is molded, manufacturers can commit their resources to the final mold, reducing time to market.

SmarTooling relies on the heavy use of scientific data and analysis, rather than trial and error, Castañeda says. The traditional product development cycle includes weeks of work on the prototype -from tooling, validation, and testing to engineering changes, retooling, and retesting. PDT's SmarTooling cycle (Table 1) emphasizes the mechanical design and analysis stage, producing accurate data that allow designers and moldmakers to bypass later time-consuming prototyping stages. "Not only should prototypes be representative of the production process," Castañeda says, "they should be the production parts."

Tooling Strategies
In addition to the use of scientific analysis in the design stage, SmarTooling replaces traditional toolbuilding methods with a series of four tooling strategies that help build a production mold faster.

The first strategy employs EDM to burn as much detail as possible on the core and cavity steels. Individual burn features are combined so that the total number of electrodes is reduced and the burn time is minimized. PDT generates EDM table data via a proprietary process, using Pro/E, that helps reduce errors in the burn process.

PDT recommends burning an EDM texture that simulates the desired finish on the part-even on first pass. The advantages are that the results are closer to production runs, and hidden part-sticking issues become apparent sooner.

CAV, a laser scanning inspection tool, checks dimensions. Critical geometry electrodes are scanned prior to burning. Cores, cavities, and any steel that touches the plastic are scanned after EDM burning to check compliance with the 3-D mold database. Molded parts are also scanned with the CAV system. Finally, PDT produces tools in hard steel (S-7, H-13); it calls a soft steel, limited-use tool a waste of money and time.

The SmarTooling system came in handy for Motorola engineers who needed tooling for an entire program in four weeks. PDT's SmarTooling process offered Motorola the lead time it needed, as well as mold design services, electrode design services, and tool manufacturing using Pro/E throughout the process-all to produce its line of Nextel mobile phones. Motorola also leveraged PDT's use of CAV to expedite part qualification. "We wanted to locate moldmakers that used Pro/Engineer because we could archive the mold data onsite in a readable format," says David Johnson, engineering section manager for Motorola in Boynton Beach, FL. "This allowed tooling engineers and part designers to analyze the effect of future part design changes on existing tooling."

Cost vs. Benefit
PDT's SmarTools cost about 11/2 times what a traditional mold costs Motorola, Johnson reports, but the time savings translates to a large dollar savings for high-volume production. As with any technology, there are limitations to SmarTooling. The cost of an engineered mold must be analyzed, factoring in the number of units that must be produced to achieve savings. Another factor is that production managers must consider the whole supply chain to ensure that other materials and parts are available for an accelerated production cycle.

Although a variety of markets currently use or could use SmarTooling technology, some are more conducive to the process, such as electronics, household, and automotive. Generally this is because their markets require higher volumes, enhancing the cost benefit.

"We will continue to evolve our SmarTooling process, Pro/Engineer continues to advance, and with new manufacturing technology, we will see lead time cut to two weeks in the near future," Castañeda says. This thinking may be controversial, he admits, but the evolving injection molding market demands new and different approaches to traditional tasks.