Originally Published MPMN March 2002

PRODUCT UPDATE

Suppliers Make an Impression on Medical Devices

Printing and surface-treatment providers offer a range of device-finishing services

In many cases, medical devices are not quite finished when the manufacturing process is over. Often, these products have to be treated to remove organic and inorganic contamination, increase wettability and bond strength, and remove residue, among other things. Additionally, it is generally at the end of the process that the products are printed and labeled.

This article looks first at some methods for treating the surfaces of medical devices. These techniques are used to degrease metal, to provide protection for substrates, and for deburring, surface smoothing and polishing, ball burnishing, cleaning, and pickling or descaling. Second, it explores some innovations in printing methods.

Whether you are sourcing surface-treatment or printing supplies or services, the accompanying Buyers Guide grid starting on page 48 provides a comprehensive listing of suppliers complete with contact information and an indication of their core products.

Plasma system treats plastic, rubber, and metal

A system developed by Tantec USA creates a plasma discharge under vacuum and is suitable for surface activation on complex-shaped plastic and rubber products, as well as for metal degreasing. Plasma treatment is a batch process, and the size of the vacuum chamber can be customized to meet the required output capacity and to accommodate larger products. All process parameters are adjustable and automatically controlled with a PLC. The process data, treatment time and power, and vacuum level are monitored and displayed on a control panel. The vacuum pump is available in a range of 40–100 m³/hr, and can either be integrated into the machine frame or mounted on a separate pedestal.

Flat-bottomed vibrator gently processes large-part volumes

A flat-bottomed vibrator enables extremely gentle work-part processing. The CM 1045 multipurpose finishing machine from USF Surface Preparation Group, Walther Trowal features a 4.1–12.4-cu ft capacity with a 13-in. maximum workpiece dimension. It can be used for deburring, surface smoothing and polishing, ball burnishing, degreasing, surface cleaning, and pickling or descaling. The unit comes with a welded work bowl with a molded wear-resistant polyurethane lining, a direct-drive electric motor, and an integrated triangular wedge on the work bowl's outer wall that ensures optimal movement of media and parts. An optional large-diameter, pneumatic unloading plug allows for the quick discharge of parts and media from the work bowl, which prevents mixing of parts from different batches. The CM 1045 is suitable for double-batch operation, eliminating unproductive idle time.

Aqueous-based lubricious coating reduces tissue trauma

A water-based coating technology provides lubricious, low-friction surfaces that greatly reduce tissue trauma during repeated insertions of a variety of medical devices.

Lubrilast, offered by AST Products Inc., provides an alternative to the lubricious coatings currently available for medical applications. The formulation is completely water based. It does not contain any organic solvents and does not require UV light for curing.

Lubrilast is made of a hydrophilic polymer entwined in supporting polymeric network that undergoes a cross linking reaction to form a durable hydrogel coating. It is then fully cured under low-temperature drying conditions.

"The simple application process of Lubrilast is particularly beneficial for any device that is composed of light, heat, or solvent sensitive materials," says Ih-Houng Loh, the company's president. "It is also a cost-effective coating technology since no solvent-handling or explosion-proof equipment is required, and disposal costs of unused coatings solutions are minimal due to its nontoxic nature."

The product is available to medical device manufacturers through licensing arrangements with technology transfer and contract coating options. According to Suzanne Conroy, coatings group manager, Lubrilast has already been licensed to several medical device companies and more agreements under development. Examples of products coated with the material include cardiovascular catheters, intraocular lens injectors, neurovascular catheters, and catheters for urological applications.

The technology can be customized to incorporate antimicrobial, antithrombogenic, and other therapeutic agents as well as lubricious polymers. Almost all polymers, metals, and ceramic materials used in medical devices can be coated.

Cylinder-printing device

A technique and device are available for decorating the outer circumference of tubes or cylindrical items up to 360° or more for overlap. The device developed by Pad Print Machinery of Vermont Inc. consists of a cliché up plate with an etched image as well as a linear-shaped silicone printing pad that transfers the image to the cylindrical object. In addition to the cliché and pad, a fixture is included to support the cylindrical item. The silicone fixture has a flat surface with a row of holes for a vacuum and a lip to act as a stop point or position reference for the item to be printed. The tube or cylinder is placed on a slide unit that allows it to move on the horizontal axis. A pad slide unit can also be used. The pad above is mounted on a slide, thus enabling the fixture to remain stationary and the pad to move. The process allows the cylindrical item to be rolled while it is being pinched between the pad and the flat silicone plate, thus transferring the image onto a part of or the entire circumference in a single operation.

Printing services

As a custom printing supplier, Isoprint provides specialized services such as versatile imprinting on substrates including nylon, polyurethane, PVC, PP, PE, glass, ceramic and metal; gas-plasma surface treatment; and tracking systems and product management. All of the company's medical device and component printing uses Class VI medical-grade inks designed to withstand repeated sterilization procedures. These inks, available in a variety of colors and formulas, meet exacting industry requirements for nontoxicity and biocompatibility.

The company's plasma-gas treatment eliminates surface contamination and ensures adhesion for medical-grade inks applied to a variety of substrates. The treated substrate contains molecular hooks to which medical-grade ink molecules attach during the printing process. After curing, the ink impression cannot be removed from the device without physically removing layers of the substrate itself. This process does not in any way adversely affect the integrity of any molded or extruded device or component.

Susan Wallace

Copyright ©2002 Medical Product Manufacturing News