Molding medical products requires injection presses, automation and inspection equipment geared for clean room molding and assembly, said speakers at an Engel North America conference.
Engel ran three demonstration machines at its Medical Days event, including one showing the first-ever use of its X-Melt technology running liquid silicone rubber. Joachim Kragl, director of advanced molding systems and processing, dubbed the demonstration “truly a world premier.”
The 30-ton e-Victory press molded a tiny check valve for controlling medical fluids. Each part weighed just 0.03 gram.
With X-Melt, the screw builds up a high melt pressure with the shut-off nozzle in the closed position. For injection, the nozzle opens up and allows the melt to shoot into the mold all at once.
“You can get extremely fast-fill, thin-wall parts,” Kragl said at Engel's “Medical Days,” held June 15-16 at the machinery supplier's York headquarters. “It's really a perfect process for small parts and micromolding.”
Since the entire mold is filled at full melt temperature, the material picks up all details of the mold.
Using X-Melt for micromolding allows for a larger-tonnage machine for a high degree of precision. Kragl said the machine can do 10 microshots before the screw needs to recover more material, providing accurate dosing.
The e-Victory machine was equipped with the hybrid Ecodrive, which marries an all-electric injection unit with a servo-driven hydraulic pump to run the platen movement. The pump runs only when needed and reduces heat loss into the clean room.
Christoph Lhota, vice president of the medical business unit at Engel Austria GmbH, said the Schwertberg, Austria-based injection press maker dedicated a team to medical molding five years ago.
A fast machine is important, since many medical parts have long cores. All-electric presses have become the most popular medical machine, he said.
“Our choice was, we took the clamping technology from our packaging machine and electrified it,” Lohta said. Since then, Engel has built about 300 medical presses a year.
Steve Broadbent, process engineer of Engel's LSR and elastomer machinery, reviewed several LSR applications including a seal ring for a dialysis filter, a silicone valve for needle-free coupling of ports and a face mask for sleep-apnea patients.
“We all know the problems hospitals are having now, where patients come out with infections, Broadbent said. “So LSR gives you the ability to make a disposable, single-use product.”
Keeping the process clean is critical. Lohta noted that Engel's research shows that the press itself — whether hydraulic, hybrid or all-electric — has a low impact on particle-count contamination in a clean room.
However, contamination does result from purging material out of the press. Engel uses barrel exhaust to remove both heat and contamination during purging. For mold changes, rollers can be incorporated on the platens, so molds roll in and out.
Engel links full process documentation, required for medical molding, for the press and all automation, which is run through the machine controller, Lohta said.
Automation plays a key role in medical molding, both to ensure quality and keep the process clean, said speakers at the event.
“The greatest source of contamination is the people inside the clean room,” said Morgan Polen, vice president of application technology at Lighthouse Worldwide Solutions, a Fremont, Calif.-based maker of contamination monitoring systems.
Attendees heard from representatives of automation specialists Hekuma Automation LLC of Ann Arbor, Mich., and Waldorf Technik Inc. of Hamburg, N.J. A high-speed Hekuma side-entry robot removed petri-dish tops and bottoms from a 16-cavity mold on a 310-ton Engel e-motion press, assembled and stacked them and enclosed them in a plastic bag.
Automation systems can be designed specially for clean rooms, said Hekuma Automation President Mike Walper. That includes covering and sealing off any moving parts, using low-abrasion cables and hoses and using smooth, round corners, which are easier to wipe clean than sharp corners.
Robert Herman, sales manager of Engel's medical business unit, said drives and bearings are encapsulated on the petri-dish cell. “They're all enclosed so there's no potential for contamination from moving parts,” he said.
Waldorf Technik supplied full automation for a 110-ton Engel e-max molding pipettes on a 32-cavity mold. The system included 100 percent vision inspection with a six-axis articulating robot removing parts and presenting them to a camera mounted into the molding cell.
Waldorf business development manager Lisa Mauro said in-line automation is better than off-line — where parts free-fall out of the mold and must be aligned for downstream work. In-line automation can provide cavity separation, which is important for part traceability.
“Downstream is not the time you want to find out that cavity eight is having problems,” she said.
Attendees also learned about a metal alloy. Thomas Steipp, president and CEO of Liquidmetal Technologies Inc., held up a metal replacement knee joint made from the material. Liquid metal is 21/2 times stronger than titanium, he said. Like plastic, it does not shrink when processed. “We can get machined-like parts out of the mold,” he said.
Rancho Santa Margarita, Calif.-based Liquidmetal has partnered with Engel to target precision-machined parts, at dramatically lower costs, Steipp said. The firm has installed two Engel presses at its headquarters, retrofitted to make the metal parts.
He said the firms are working to make machines for higher-volume production.