Thick-gauge thermoformed plastics can be used for medical applications such as MRI and blood analysis equipment and CT and PET scanners. The technology produces durable, lightweight parts with antiabrasion properties, crisp features, and fine surface detail. Moreover, some vendors can thermoform parts as large as 9 X 13 ft, expansive enough for even the largest MRI covers, and options now include embedding antimicrobial materials and twin-sheet thermoforming.
Historically, oversize parts for MRI, PET, CT, and other medical equipment have been molded from fiberglass. However, fiberglass has size, wall thickness, and radii limitations, and it is typically heavier than thermoformed parts, which are stronger at half the cost, according to Wynn Kintz, President of Kintz Plastics.
"Thermoformed plastic is the logical upgrade from fiberglass when large medical parts, panels, housings, or enclosures are needed that must be durable and lightweight, yet aesthetic and affordable," says Kintz. His thermoforming business has caterered to medical device manufacturers for almost 40 years.
Kintz claims that he has the the largest four-station rotary thermoforming machine in the Eastern United States. Few thermoformers have the resources for such a large capital investment, says Kintz. His company is able to thermoform parts up to 9 X 13 ft. with a 60 in. draw, he says.
Upon request, the company can add an antimicrobial agent to the material during the manufacturing process. The agent prevents bacteria, fungi, mold, and mildew from collecting on the surface or substrate, and it will not wash or wear off.
Twin-sheet thermoforming is available for medical device parts, panels, or enclosures that will be seen from both sides, need added strength, or that will house insulation or mechanical or electronic components. The process simultaneously thermoforms two sheets of plastic, which are bonded together to create a double-walled structure that is durable, lightweight, and economical.
"Since twin-sheet thermoforming replaces two processes with one, it saves time and labor, creates a seamless part and stronger structure, and results in a lighter, more cost-effective component," explains Kintz.
The use of twin-sheet thermoforming in the redesign of enclosures for a medical diagnostic device reduced the cost of the doors by 30 to 50%, compared with a fiber-reinforced plastics (FRP) process, according to Kintz. "Compared to injection or blow molding, twin-sheet thermoforming can reduce tooling costs by up to 90% and cut tooling development time in half," he adds.
Kintz also advocates early vendor involvement in a project and cites as an example a recent partnership with Beckman Coulter, a company that develops, manufactures, and markets biomedical testing products. The company's diagnostics division in Chaska, MN, reportedly benefited from input from Kintz engineers on the manufacture of blood analysis instrument parts.
"Engineers know the required design outputs, but the product can benefit from expert vendor input," says Sean Peters, a senior procurement analyst in Chaska, Minn. "When Kintz Plastics helped our engineers with thick-gauge thermoforming material selection and manufacturability on several blood analysis instrument parts, we achieved at least 20% cost savings, 20% time savings, and enhanced quality with a three-month ROI on the tooling." The consultation also helped the company enhance the function and aesthetics of several parts.
"Several vendors had previously refused to even quote us on a part—a hopper shell to contain reaction vessels—because its shape was unique and difficult to make," says Peters. "Another part, a sample presentation unit input door, required a clear, high-impact, blemish-free surface for easy viewing. Kintz Plastics worked with us on both these high-tolerance parts to get the precision and aesthetics just right," says Peters.
For instance, to enhance the appearance of six covers in a Vein Viewer device that makes veins visible to the naked eye via projection of a real-time image of the underlying veins onto the patient's skin, Kintz's company recommended a design with a formed-in undercut. This enabled the covers to fit so precisely together on the unit that all the seam lines are uniform once assembled.