Harnessing the Power of Plastics

THE TOOL

Forming for the DPM process is done in proprietary thin-shell composite tooling, which typically can be produced far more rapidly than conventional compression tooling (e.g. 2-4 weeks vs. 6-12 weeks for aluminum) and far more economically ($15,000 to $25,000 USD vs. $60,000 to $100,000 USD for aluminum). Since each DPM tool is thin, it can be heated and cooled much more quickly than conventional composite or metallic tooling. Therefore, it takes much less time and energy to heat and cool than other tooling technologies, further simplifying equipment, costs, and energy requirements, and shortening molding cycles. In fact, because these thin-shell tools are fast to heat and cool, it is not necessary to install water lines, helping keep both cycle times and cost down. Optional high-temperature tooling resins can be used for molding temperatures up to 350F / 177C .

Because force is applied equally across the entire mold and the dies are thin, tooling reinforcement (steel blocks) is unnecessary. This means that DPM tools are quite light (typically around 50 pounds / 23 kilograms per tool half), so they are easy to change out, move, and store (without use of a forklift and a skilled operator to run it). In turn, a far simpler clamp / frame is required to hold them during processing. Additionally, no special storage is required for the molds, which can be laid on their side in the work cell near the press. Neither do they require high-strength die racks as are common with steel or aluminum tools.
DPM tools do not have shear edges as are often used with high-speed compression molding, so post-mold trimming of parts will be required upon demolding.

While the DPM process was initially developed for production manufacturing, the low cost and rapid turnaround of DPM tooling means this process is also ideal for use in prototyping operations.  DPM can also be very cost-effective for programs with low-to-very-low production volumes, where the high cost and long lead times for producing steel or aluminum tooling is cost-prohibitive, and where the high cycle times typical with conventional epoxy compression tools makes piece-price uncompetitive. With the DPM process, our thin-shell composite tools run at cycle times typical of steel tooling – 30-90 seconds / cycle depending on part size and geometry.

During prototyping or production launch, should significant mold changes be required, with DPM it is faster and less costly to create a new mold than to build up a bank of molded parts and wait for steel or aluminum tooling to be modified. 

Unlike solid steel or aluminum tools, which are designed to maintain a specific gap based on specific materials, DPM tools can run on force without stops, so a wider range of materials (and charge thicknesses) can be tried without making tooling changes – an ideal situation for prototyping operations where a variety of materials are being trialed.

Depending on geometry, it is often possible to build only single-sided tools (with the second half being replaced by a rubber bladder). While this is faster and less costly tooling, it obviously requires some design concessions (e.g. no sharp details and a non-visible back side, since the substrate material will not be flattened / consolidated well by the rubber bladder). Single-sided tools are extremely easy to modify, so this technique can be useful in early stage prototyping.

Our conventional thin-shell composite tools can be cast from an existing part, clay or wood model, or many other structures. The model should be cut as an “A-surface” male and some consideration should be given to shrinkage of the molded part to allow for demolding. For reference, the first “pull” off the tool is from the A-side.

For even lower cost tooling for very-limited production runs (50 or fewer parts) and extremely fast turnarounds, a different base tooling resin can be substituted that sets up in as little as 30 minutes. These tools cannot withstand prolonged heat the way our conventional DPM tools can, but this is an option for specific situations where extreme speed is needed.