Medical molding requires top-notch molds, machinery and clean rooms — and a good understanding of validation requirements from the Food and Drug Administration, according to speakers at an Arburg Inc. seminar.
About 85 people attended the event, held June 24 at Arburg's technical center in Elgin.
Richard Gane of Neuhausen, Switzerland-based mold maker Kebo AG, said a high-quality medical mold provides faster cycle times, fewer scrap parts and what he called “higher availability” —meaning the mold will run reliably on a 24/7 basis.
Gane said medical plastics companies should consider their tooling supplier as a partner.
“The mold must be perfect when it comes into your factory for production. You do not want to start playing around with it in your place of production,” he said.
Gane also advised against taking the “cheap route” when picking a mold supplier. “Efficient production is far, far more important in the long run than saving a little bit of money on a cheap mold,” he said. He also suggested keeping spare parts of wear items.
During the medical seminar, Arburg ran protective caps for syringes on a 48-cavity, hot-runner Kebo mold, with a cycle time of 4.9 seconds, on an all-electric Allrounder 470-A with 88 tons of clamping force. Gane said that is actually a pre-production mold — the final full-production mold will run 256 cavities, he said. High-volume molds are the heart of the process for making high-volume disposable medical products.
Arburg ran two other presses: a 143-ton Allrounder 520-A molded two battery covers on a 1.5-second cycle; and a 110-ton Allrounder 420-C turned out four operating buttons for a hospital bed on a 12.1-second cycle.
Martin Neff of Arburg said injection presses for high-cavitation medical molding have different features than those for general-purpose molding: They need a larger clamping area and tie-bar spacing to accommodate multicavity molds, but generally have a smaller shot size. The clamping unit must be rigid and robust, he said.
Medical requires “process stability, process security and in-line data gathering,” said Neff, sales and engineering manager of the technical center.
All-electric machines are often the choice for clean rooms, but core-pull functions are usually done by hydraulic power. Neff said Arburg integrates the core-pull hydraulics and a temperature-control unit into the machine base. Neff also advocates direct-drive machines for their efficient movement to speed up and slow down.
Typically, clean rooms contain entire molding machine. But Neff said you can build a modular clean room around a single press, on the part-ejection side, and use a side-entry robot placing parts on a conveyor than runs into the clean packaging and assembly area. Presses also can sit outside of a larger clean room and eject parts into the room. Still other devices sit on top of a press and create a curtain of ionized air around the clamping area.
Seminar attendees got an overview in clean room technology from Kevin Hennessy of Starrco Co. Inc., a company in Maryland Heights, Mo., that makes clean rooms and modular offices.
“Most clean room contractors have built clean rooms for injection molding companies. You've been a great industry for us,” he said.
Clean rooms use positive air pressure to constantly exchange and filter the air to remove particles of contamination. The air returns are located on the floor.
Hennessy said a dedicated air-conditioning system is needed, since an entry-level, Class 100,000 clean room changes the air 20-30 times an hour, while a typical air-conditioning system does six to eight air changes.
Fan filters are put in above the ceiling. Installers tightly seal all ductwork and light fixtures.
Clean rooms can be expensive, even more so if the ceiling is higher than it needs to be, so Hennessy advised careful planning. Another lower-cost option: a “soft wall” clean room that uses a vinyl curtain to create a limited space.
Joe Rettinger delivered an FDA Validation 101 lesson. He is validation program manager of Emergo Group of Arlington, Texas.
In the past, Rettinger said, FDA enforcement has been inconsistent, but that is changing.
The agency has added more than 800 staff members to conduct inspections, he said. And the FDA has started pushing medical-device manufacturers to validate their suppliers — including plastics molders.
Process validation is “a means of ensuring quality where 100 percent post-production testing is not possible,” Rettinger said. That means keeping the process under control and maintaining records.
“Process” covers areas such as equipment, calibration, settings and controls, resin, enterprise resource planning systems, staff training, safety and clean rooms.
“Validation has to become a way of life,” Rettinger said. “Validation is ongoing process control. It's not something you can do and set aside.”
Cracking into the medical market is not easy, but Terry Kochersperger explained what Baxter Healthcare Corp. looks for in a molder.
Baxter does plenty of its own plastics processing, running about 140 million pounds of plastic a year on more than 150 injection presses, 20-plus sheet extruders and more than 80 tubing extruders, he said.
Kochersperger, vice president of global manufacturing operations at Baxter's technical center in Round Lake, Ill., said company officials prefer to conduct site visits at prospective suppliers. They look at how clean and orderly the plant is, and things like parts separation by cavity, and scientific molding practices, he said.
Bernie Stritzke outlined thermoset rubber molding as it is done at Medplast Inc.'s plant in Elkhorn, Wis., where he is vice president and general manager. Because the rubber molding industry doesn't have a lot of standardized materials and compression molding machines, processors do custom formulations, he said.
The medical market is heating up demand for liquid silicone rubber parts, which offer a very fast cycle time compared with traditional rubber. “You could really compare a lot of these [LSR] cycle times to thermoplastic injection molding,” Stritzke said.
In the second half of 2010, Arburg of Newington, Conn., plans to hold an automation forum and an LSR event, according to President Friedrich Kanz.