September 2005

A Clean Slate

Membrane-pressed thermoplastic sheet keeps medical equipment safe and secure.

Midmark Corp. has begun building medical supplies like this cabinet using membrane pressed thermoplastic sheet.

When it comes to controlling infections in a medical office, a lot depends on the cleanability of work surfaces and equipment.

That is exactly why Midmark Corp., an Ohio-based supplier of healthcare products, switched from laminate tops on its medical carts and cabinets, to surfaces membrane pressed of a proprietary thermoplastic sheet.

Employed in exam rooms, clinics and multi-physician practices, the company's Midmark and Ritter series, which include procedures carts, treatment cabinets and mobile desks, help physicians access critical items at the point of care without fear of spreading infection form their medical equipment.

"To eliminate the threat of bacterial growth and the transmission of viruses and other germs, our customers require work surfaces that will not absorb spilled fluids and chemicals, and that can be easily disinfected," explains Jon Wells, director of marketing for Midmark. "Membrane pressed Kydex 150 sheet provides our carts and cabinets with seamless work surfaces that are very cleanable, durable and aesthetically pleasing," he adds.

Scott Strait, Midmark's chief engineer, knows the company's products will not only have to contend with bacterial growth, but likely cleaning products on a daily, or even hourly, basis.

Membrane pressing allows the thermoplastic sheet to form to all top and side surfaces of the MDF substrate.

"Extreme chemical resistance is also critical," Strait says. "Not only is there a potential for spills, but the surface is disinfected multiple times each day with harsh cleansers. Kydex 150 sheet exhibits greater chemical resistance than a typical laminate."

Unlike many other plastics, thermoplastic sheet also resists exposure to lipids present in body fats and gamma radiation, making it particularly well suited for medical applications.

"Our carts and cabinets must also be scratch and abrasion resistant and able to withstand a lot of abuse," says Wells. "The melamine and laminate surfaces we've used in the past would begin to show scratches after only a brief time in the field, something we haven't experienced with our countertops membrane pressed with the Kydex product."



In addition, the color of the proprietary sheet is integral, unlike that of high-pressure laminates, rendering gouges and scratches inconspicuous.

Seamless Cleanability

This thermoplastic sheet brings with it another advantage over laminates, Strait contends. Not only does the sheet prevent bacteria from absorbing, but the very nature of membrane pressing also helps to reduce the amount of surface area where bacteria can hide and grow.

"With laminates, the edgebanding creates a seam that appears inconsequential, until you consider the chemicals and bacteria these work surfaces might come in contact with during the course of the day," Strait says.

Membrane pressing, however, allows the thermoplastic sheet to conform to all top and side surfaces of the MDF substrate, including compound curves, sharp edge profiles, rounded corners and undercut edges. All areas can be covered except the bottom surface, which can be flat laminated beforehand with the same sheet, or pre-laminated with melamine.

Midmark's customers are looking for medical equipment that will not absorb fluids and chemicals, says Jon Wells, director of marketing.

Midmark outsources membrane pressing of its parts to R&R Fabrications of St. Henry, OH. Prior to membrane pressing, the MDF substrate is routed to create detailed edge profiles and compound curves. Machined components are then coated with a heat-activated adhesive and placed on a membrane-pressing table. A specified or custom color of the thermoplastic sheet with a P-3 Velour texture is then placed over the components, and the table is slid into a chamber that heats the sheet and activates the adhesive. A vacuum from below and pressure from above forces the softened sheet onto all top and side surfaces of the MDF core, after which the parts are removed, cooled and trimmed, finally ready for assembly.

A steel shell supports the wood top, already membrane pressed with thermoplastic sheet, and the vacuum-formed vinyl drawer and door fronts, creating an overall feel that is "very warm and less institutional," Wells says.

"We compete with local wood shops as well as manufacturers of heavy steel products," he adds. "With a steel structure and membrane pressed components we offer a solution that is both attractive and functional."

                                                                                                                                                                                           

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