Expert system watches over the molding process.

Efforts to combine computer-aided-engineering with injection molding process control come to commercial fruition next month when Moldflow Corp., Lexington, Mass., rolls out its new "Moldflow Plastics Xpert" (MPX) system. Working alongside the machine controller, MPX automatically determines machine set-ups, optimizes molding conditions, and makes process corrections as needed, explains Roland Thomas, Moldflow's v.p. of R&D.

MPX evolved from Moldflow's earlier Intelligent Process Control (IPC) system, which sought to combine mold-filling simulation results with real-time process control. But MPX differs from its predecessor in ways that should broaden its appeal. For one thing, the system can be used either with or without inputs from mold-filling simulation. For another, it doesn't infringe on the machine controller's job by adjusting process parameters on the fly - that is, within the molding cycle. It only makes changes in the following cycle. Finally, MPX features completely revamped hardware that allows easier integration into a molding cell. "This is not a re-launch of IPC," says marketing v.p. Ken Welch. "It's a brand-new product."

Accomplishes three tasks

MPX consists of three bundled software components, all of which rely on a rule-based expert system to achieve MPX's three goals: to set up, optimize, and monitor the process.

* "Set-up Xpert" provides a systematic method for mold set-up. It begins with processing and part-tolerance targets obtained from any of three sources: a Moldflow simulation, a direct upload of existing set-up parameters, or a "set-up wizard" that walks users through the appropriate inputs. It then optimizes processing parameters - including cooling time, shot size, velocity profile, packing pressure and time, and pressure profile.

* "Moldspace Xpert" establishes a molding window by running a simplified Design of Experiments (DOE). The software guides users through the DOE, which typically takes eight shots to complete. Users enter defect information from a drop-down menu after each shot.

* "Production Xpert" monitors user-specified process variables. If they stray from their control limits, it sends an alarm and suggests corrective action. Or users can enable the software to correct the process by downloading new setpoints to the controller in time for the next shot.

Easier integration

Compared with the earlier IPC system, the most obvious differences in Moldflow Plastics Xpert hardware are its size and relative simplicity. Its machine-side box is not much bigger than a PC housing and is built from off-the-shelf rather than custom components. MPX requires only three standard machine signals - hydraulic pressure, screw displacement, and injection start - though other signals can be utilized as well. "MPX takes only about an hour to hook up," Welch says.

Currently Moldflow has integrated MPX with machines from Battenfeld, Engel, Van Dom Demag, and Ube. Welch says software drivers to connect to other vendors' machines will be made available as needed by customers.

Moldflow has a few systems in the field, including at least one in the U.S. Most of them are still under evaluation, but Denso Manufacturing in Australia is using MPX in full-fledged production.

When it becomes commercially available next month, Moldflow Plastics Xpert will cost between $20,000 and $25,000.