Powder impression molding process is rollingPowder impression molding process is rolling

A U.K. company licensing a somewhat mysterious new molding process invented in the U.S. likes its chances of success, as it''s capable of turning out products as diverse as 100% recycled-plastic roof slates, low-weight truck beds, and boat hulls that rival glass-reinforced thermoset composite types.

Five years ago, 3DM Worldwide plc, previously called Camco Corp., (Witney, U.K.), signed a deal with DaimlerChrysler to develop a pickup truck rear box made by powder impression molding (PIM; not to be confused with powder injection molding, the process was developed by 3DM Technologies Inc. in Detroit, MI; Camco bought that company, and changed its own name when it saw the value of the process.) When the head of DaimlerChrysler saw the product—a one-piece unit with integral steel framework and integral coloring that came in 43 kg lighter than a steel version—at the Detroit Motor Show in early 2002, he said he wanted it on the next Dodge truck.

Things have not gone completely according to the original plan, but they are moving in the right direction. Global Technologies Inc. (GTI), a Detroit company associated with 3DM, is now handling a project for making PIM truck beds for the aftermarket, but the numbers currently are low. 3DM remains optimistic that one day the process will be used for series production of OEM truck beds.

In the meantime, 3DM has been at work on numerous other fronts. Last September, it sold its first PIM license to a U.K. company for an unspecified building product to be made on a robotized line currently under construction—the first of its type. It has also signed a deal with leading yacht designer Bill Dixon for production of PIM yacht hulls by Highseas Technologies, a startup company in which it has interests; first prototypes should be ready this year.

Through GTI, 3DM is also involved in a major project in Mexico that will lead to the production of low-cost housing panels using PIM, and is expected to garner at least $15 million over the next five years for 3DM. PIM can be used to make floor and wall panels in place of cast concrete. It weighs far less, provides thermal and acoustic insulation, and enables ducting to be molded in-situ.

PIM basics

So what is PIM? 3DM won''t reveal much about it, and no photos of the equipment are available for publication. It appears similar to slush molding, although it works with granular materials rather than powder. Parts can incorporate reinforcing inserts, as well as particulate reinforcement such as fibers or beads.

In producing the truck beds, the two skins of a bed are produced by filling preheated open molds with granular polymer, allowing the skins to gel, and then pouring off the excess material. Reinforcements are then laid on top of the lower skin and more granules and blowing agent are poured on top, and the mold half containing the upper skin is laid over that. The two mold halves are then clamped together and the assembly is heated to foam the core and join the two skins together. Skin thickness can vary from around .5 mm to more than 4 mm across the surface of the part.

The entire process takes about 25 minutes, but use of multiple molds can reduce the effective cycle time to a level suitable for industrial application. Since the process operates low pressures, the molds can be made using low-cost processes. Four sets of tools should cost less than $2 million.

Miguel Linares is chief technology officer of 3DMTI and one of the inventors of PIM. "This is the only process in the world that allows you to vary the wall thickness of the part from 1/8 inch to 3 inches without altering the geometry of the mold," Linares says.

"For example, the customer may decide to go to a thicker cross-section on a part because it may need more strength. Unlike traditional molding processes, [PIM] does not require any modifications to the tool. The same tool that was producing the 1/8-inch thick part can now produce a 1-inch thick part, instantly."

Peter Mapleston [email protected]

Contact information
3DM Worldwide www.3dmworldwide.com