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Articles from 2001 In September


Conductive Urethanes Retain Key Properties

Originally Published MPMN September 2001

PRODUCT UPDATE

Conductive Urethanes Retain Key Properties

Materials combine static dissipation with toughness and elongation

Selectively enhanced polymers from Foster Corp. combine conductive properties with the toughness and flexibility of polyurethane.

Enhancing certain properties in a polymer traditionally has meant accepting trade-offs in other areas. Selectively enhanced polymers (SEPs) promise to change that equation. The technology has been applied to the formulation of conductive urethanes.To promote static dissipation in urethanes, suppliers typically add a compound that affects the material's other properties, or they may use an external static dissipation system whose effectiveness erodes over time. By leveraging SEP technology, one company has developed a line of conductive urethanes that provide static dissipation without a loss in flexibility or other mechanical properties. This technology and other developments in medical-grade materials are discussed in this section.

Inherently nonconductive, thermoplastics must be modified to dissipate static charges that can damage electronics. Traditionally, urethane fabricators have promoted electrical dissipation by introducing internally compounded additives, such as carbon. The trade-off has been a decrease in material toughness, elongation, and other key mechanical properties.

To address this issue, Foster Corp. has created SEP conductive urethanes that combine static dissipation with the flexibility and mechanical properties of urethane. To achieve this result, Foster uses a blend of highly structured carbon additives and compounding techniques.

"Static charges can be an engineer's worst nightmare, since they jeopardize sensitive electronic components," says company president Larry Acquarulo. "Conductive materials give these charges a path to dissipate without destroying the product. Yet the sacrifice in toughness and flexibility from traditional carbon-filled polymers is unacceptable for belts, tubing, and other flexible components."

The company's SEP conductive urethanes exhibit as much as 300% elongation, but are specifically designed for applications with 105 (omega)/sq surface resistivities. The combination of properties enables optimal consolidation of components, increasing design flexibility and reducing overall product costs, according to the company. The SEP urethanes can be processed using standard extrusion, molding, and other manufacturing techniques. Applications include tubing, film, sheet, and injection-molded components.

Polyurethane lines offer strength and heat resistance

Urethanes offer a combination of properties such as toughness, a soft feel, and ease of fabrication, as well as resistance to microbes, skin oils, moisture, and a range of chemicals that make them suitable for use in demanding medical environments. They can be sterilized by most common methods, including gamma, with little effect on performance.

A line of polyurethanes that includes different degrees of hardness is offered by Stevens Urethane.

A line of polyurethanes from Stevens Urethane combines the properties of rubber and plastic to offer high performance and reliability for applications including burn blankets, breast prostheses, wound dressings, cold packs, and tubing. The company provides three materials with varying degrees of hardness. MP-1880 is a general-purpose urethane that features an 87 Shore A hardness rating, good abrasion resistance, and a 60°–200°F maximum service temperature range. MP-1882 is a softer, more pliable grade that is soft to the touch; the 82 Shore A hardness material is suitable for applications involving long-term skin contact. MP-1890, with a 90 Shore A hardness rating, is designed for applications in which greater temperature parameters and puncture resistance are required, such as cold packs. The urethanes are available in 0.001–0.125-in. thicknesses, in widths starting at 5 in., and in a range of colors, opacities, and surface textures. Tubing comes in 1/16–1/4 in. ID and 1/8–1/2 in. OD with 1/32–1/8 in. wall thicknesses.

Vantico Inc. has added two new polyurethane compounds to its Parts-in-Minutes line. The compounds are designed for quick molding of tough prototypes and short-run parts. The RP 6462 R/H Fast is a high-impact-strength, high-heat material that is intended for rapid, efficient molding of polyethylene-like parts. RP 6463 R polyurethane resin along with slow or fast hardeners is formulated for the rapid production of clear, thermoplastic-like prototypes and parts with good UV stability.

RP 6462 R/H Fast can be dispensed by means of automated meter/mix equipment. Jet-black in color, the material gels in less than 50 seconds and can be demolded in about 5 minutes. After a room temperature cure, the polyurethane exhibits 2.3-ft lb/in. notched Izod impact strength, 194°F heat deflection, and 120,000-psi flexural modulus. Mechanical properties can be enhanced with a postcure process.

RP 6463 R is suited for parts from 1 in. thick with a fast system to 2–3 in. thick with a slow system. The room temperature demold time ranges from 4 to 16 hours, depending on the hardener or hardener combination that is used. Once cured, 136° to 152°F heat deflection temperatures and 1-ft lb/in. notched Izod impact strength can be achieved. The molded products have a flexural modulus in the 240,000-psi range and 79 Shore D hardness.

Laminated COC provides a high moisture and oxygen barrier

COC film from Klöckner Pentaplast provides high thermoforming yields.

A cost-effective cycloolefin copolymer (COC) laminated film offers high moisture and oxygen barrier properties for blister packaging applications. The Pentapharm COC SD/03 is a rigid vinyl/COC/PVDC laminated film that seals to common vinyl and PVDC lidding materials. Available from Klöckner Pentaplast of America Inc., the coextruded film has a low specific gravity, which results in higher thermoforming yields. In addition, the film has the thermoforming capabilities of vinyl as well as good optical clarity. Pentapharm films run on standard thermoform tooling. "The material benefits medical manufacturers by offering them a material that has both oxygen and moisture barriers for any specialized products," says communications and media manager Nancy Ryan. "There is no other rigid film on the market that offers this."

Katherine Sweeny

Copyright ©2001 Medical Product Manufacturing News

PVC-Like Polyolefin and Flexible Guidewire Grinder Debut at MD&M East

Originally Published MPMN September 2001

INDUSTRY NEWS

PVC-Like Polyolefin and Flexible Guidewire Grinder Debut at MD&M East

The look, the feel of PVC

Applications for a polyolefin elastomer that mimics the soft, dry feel of PVC include IV, drug delivery, and blood processing and storage products.

Although they are not being marketed as a PVC replacement, Solmed polyolefin films captured the attention of numerous visitors to MD&M East because of their potential as a substitute material. Solvay Draka Inc. (Commerce, CA; www.solvaydraka.com) introduced the polyolefin elastomer film to the North American market at the show.

"We have had a lot of interest from OEMs sourcing a non-PVC material that has the tactile qualities of vinyl," says Solvay's director of technology Robert Elcik. Other materials that exhibit properties similar to PVC do not share its soft, dry feel, he says, thus limiting their market potential in North America.

The newest additions to the Solmed family of medical-grade materials, EM-8300, EM-8400A, and EM-8600-B4 feature minimal extractables, strength, chemical resistance, clarity, flexibility, and ease of fabrication. Potential applications include IV, drug delivery, and blood processing and storage products. The material is also suited for the production of stem cell containers and nutritional, drainage, and CAPD devices.

The product's strength-to-thickness ratio permits downgauging: a 9-mil polyolefin film has the strength and durability of a 14-mil soft PVC film, according to the firm.

Heat-weldable EM-8400A withstands autoclave, gamma, and EtO sterilization; exposure to high levels of gamma radiation, however, may result in slight visual or physical property changes. EM-8600-B4 is suited for gamma and EtO sterilization and can be either heat or RF welded. EM-8300 is RF sealable and can be EtO or gamma sterilized. It has low-temperature properties.

These films can be manufactured in thicknesses ranging from 6 to 20 mil and in widths up to 34 in. Polish/matte, taffeta/matte, and matte/matte finishes are available.

Grinder promises limitless shape shifting

Responding to customer demands for a machine that can precisely process longer wires, Glebar has developed a guidewire grinder that can produce multiple shapes with micron-level accuracy.

A guidewire grinding machine introduced at MD&M East can produce balls, tapers, arcs, flats, threads, barrels, teardrops, and a variety of other shapes with micron level accuracy. Exhibited by Glebar Company, Inc. (Franklin Lakes, NJ; www.glebar.com), the machine's versatility and ease of use received high marks from attendees, according to Robert Gleason, vice president– engineering.

"Our clients want longer, more precise wires . . . that can go into the brain to treat aneurysms, among other applications," says Gleason. Machining the guidewire shouldn't be akin to brain surgery, however, and Glebar designed the CAM SXE with simplicity in mind. For example, CAD files can be easily and quickly downloaded to the grinder from a floppy disk or network. "To my knowledge, this is the only commercially available machine with this amount of flexibility and accuracy," says Gleason.

"In the past, device OEMs have developed machines like this internally," adds marketing manager Mark Bannayan, "but they tend to be difficult to set up, and maintenance can be a problem. They also do not have the level of automation of our machine."

The CAM SXE features fully automated guidewire processing, including loading and unloading, and it is equipped with a NEMA 4 touch screen. Wire shape configurations can be specified manually or through a DXF file. Six-axis servomotors attain a 5-µm accuracy, and the grinding unit is set on a granite plate to ensure stability.

CAD/CAM software handles difficult surface shapes

CAD/CAM software with new surface-creation tools that can handle exceptionally difficult shapes was introduced at MD&M East by VX Corp. (Palm Bay, FL; www.vx.com). When working with complex surfaces, VX Version 5 users now can decide how much attraction or gravity to apply to a problem curve and thereby eliminate deformities.

The software features scores of enhancements, including manual and automatic healing of imported solid models; direct import capability of ProE, Catia, and Parasolid files; complex unified filleting via a single command, and lofting. On-the-fly access to the Cadenas parts library, which now supports VX-editable parts, and a new Windows-standard interface are also part of the package. Access to the Cadenas library of hardware, hardware assemblies, and mold frames enables parts to be pulled directly into VX assemblies, helping to speed product development time.

Medical applications of the software include an artificial hip joint design, according to senior applications engineer Mike Lynch.

Norbert Sparrow and Karim Marouf

Thin-Film Batteries Boost Design Options

Thin-Film Batteries Boost Design Options

Rechargeable thin-film batteries from Oak Ridge National Laboratory are just 15 µm thick. The power cell shown here in Figure B was constructed on the back side of the circuit shown.

Solid-state thin-film batteries with thicknesses of just 15 µm can be fabricated in most shapes and sizes to fill a variety of requirements. Developed by Oak Ridge National Laboratory (Oak Ridge, TN; www.ornl.gov), the rechargeable power cells are available with lithium or lithium-ion chemistries. The components are sputtered or evaporated onto a selection of solid substrates, including silicon, alumina, glass, and plastics. "Because the batteries are rechargeable, they only have to be large enough to supply the power required for a single duty cycle," says researcher Nancy Dudney. "So far, we have constructed batteries with areas of 0.5–25 cm2, but there aren't any fundamental lateral size restrictions, either larger or smaller." The products can be formed in almost any shape, as long as the design allows the anode and cathode to be separated by a thin layer of electrolyte.

Despite their small size, these batteries have many features. With high energy per unit of volume and mass, they can be cycled many times. The stable units also do not experience a measurable change after years of storage. A wide operating temperature range allows cycling in temperatures of –25° to 100°C. Implantable medical devices, hearing aids, remote sensors, miniature transmitters, and smart cards are among the potential applications. The batteries have also been used in transdermal electrodes to eliminate interference and improve the reliability of ECG and electroencephalography systems.

Vesta Increases Molding Capabilities

Vesta has increased its high-volume molding capabilities with the recent acquisition of K-Sil Inc.

Vesta Inc. (Franklin, WI; www.vestaweb.com), a manufacturer of custom silicone components and assemblies, has acquired K-Sil Inc. (Portage, WI), a high-volume supplier of medical-grade silicone. The acquisition expands Vesta's high-volume liquid injection molding capabilities.

The acquisition offers Vesta greater automation with better material utilization, according to company president Glenn Hubbard. "K-Sil's cold runner tooling technology is more conducive for high-volume production and will allow us to compete on a price basis," says Hubbard.

The newly acquired facility, now named the Portage Div., has a Class 100,000 cleanroom and is FDA and NSF registered.

Many suppliers to device OEMs traditionally unveil their newest products and services at the Medical Design & Manufacturing shows, and this year's MD&M East was no exception. Three products that caught our eye are described below: a polyolefin with the tactile qualities of PVC, a guidewire grinder that takes flexibility and accuracy to new heights, and CAD/CAM software that will straighten out any problem curves lurking in your design.

Zachary Turke

A New Source for Implantable PEEK

A New Source for Implantable PEEK

Device OEMs take note: you may want to add a new name to your Rolodex under implantable materials. Invibio Inc. (Greenville, SC; www.invibio.com) chose the Medical Design and Manufacturing East show in New York to announce its official launch as the sole manufacturer and supplier of implantable PEEK.

Spinal cages made of an implantable grade of PEEK promote bone stimulus and fusion.

A polyaryletherketone polymer, PEEK-Optima combines chemical and hydrolysis resistance, strength, and tribological properties with biocompatibility. Invibio currently has three grades available, which can be "custom tailored to meet specific applications and offer virtually unlimited design solutions," says company president Michael Callahan. Because the material can be extruded, molded, and machined, it offers device manufacturers broad design and production flexibility.

Invibio is wholly owned by UK-based Victrex plc, which previously offered the biocompatible material. According to Callahan, traditional business models do not necessarily apply to the medical implant market. Invibio was founded, he continues, to provide this market with a focused development, marketing, technology, and sales approach.

PEEK-Optima is manufactured under strict production guidelines, and has undergone extensive biocompatibility and biostability testing. ISO 10993 and USP Class VI test results are contained in a Device Master File at FDA. Suitable applications for the material include spine cages, bone screws and pins, hip implants, cardiopulmonary devices, and dental implantables.

Recent applications include synthetic finger-joint products manufactured by Switzerland-based Mathys Medical. The company had been using acetal, but it switched to PEEK-Optima because of its better radiation resistance and CT and MRI compatibility, according to Callahan. The material was also specified by French company Scient'x for the production of cervical and lumbar spinal fusion cages, where it replaced titanium. PEEK-Optima was deemed a superior material for these devices because its elasticity modulus closely resembles that of cortical bone, thus promoting bone stimulus and fusion.

Norbert Sparrow

Haumiller and Cincinnati Test Systems to Produce High-Speed Leak Testers

Haumiller and Cincinnati Test Systems to Produce High-Speed Leak Testers

Produced by Haumiller Engineering and Cincinnati Test Systems, this assembly, inspection, and testing machine uses continuous motion to increase throughput.

A partnership between Haumiller Engineering (Elgin, IL; www.haumiller.com) and Cincinnati Test Systems (Cleves, OH; www.cincinnati-test.com) has been formed to produce custom machinery capable of assembling, inspecting, and testing components at speeds attaining 500 parts per minute. Combining Haumiller's continuous motion equipment expertise with pressure- and vacuum-decay leak testing devices from Cincinnati Test Systems, these machines will increase throughput and reduce the number of units needed to perform these processes. According to the parties involved, the partnership is a natural one. "Cincinnati Test Systems has always produced quality hand-loaded and indexing laboratory equipment," says Haumiller chief engineer Michael Hunter. "They needed someone to adapt this technology to high-volume assembly and part-handling applications."

Traditional assembly equipment halts product output during testing. The equipment designed under this partnership solves this problem by placing a series of test stations on a continuously rotating dial. As the dial rotates, the tooling is moved mechanically to produce another seal on the part during the duration of the test. Assemblies that pass inspection are then transferred to an adjacent dial for the next operation. Because multiple stations test simultaneously, product output continues uninterrupted regardless of the required testing time.

Zachary Turke

ProFicient Wins Award for Prosthetic-Foot Shell

ProFicient Wins Award for Prosthetic-Foot Shell

A well-wrought prosthetic-foot shell design gave ProFicient Engineering Services Inc. (Corinth, TX; www.proficient-engineering.com) a leg up on some stiff competition. The company was named winner in the medical products category at the 2001 PTC Awards Competition, which was held recently in Reno, NV. Organized by software provider PTC (Needham, MA; www.ptc.com), the event honors companies that use its software to develop innovative products.

The shell is a cosmetic covering for a prosthetic foot. The ability of the designers to model the shell on the computer and include it in the concurrent design of the prosthetic foot produced a well-integrated product family with repeatable and predictable results, according to the award judges. Other finalists in the medical products category included Indigo Medical, Norwood Abbey Ltd., Edge Medica, and RefacDesign.

Karim Marouf

Doyen Medipharm Adds Sterilization to Packaging Services

Doyen Medipharm Adds Sterilization to Packaging Services

The partnership between Doyen Medipharm and Food Service Technology will offer customers one-stop sterilization and packaging services.

Doyen Medipharm Inc. (Lakeland, FL; www.doyenmedipharm.com) has partnered with Food Technology Service Inc. (Mulberry, FL; www.foodtechservice.com) to provide one-stop sterilization and contract packaging services. These services are offered to companies that outsource their packaging to Doyen or that use Doyen machines at their own facilities in the region and require a local sterilization provider. Sterilization services will also be marketed to companies in the medical industry that do not use Doyen's packaging equipment or services.

Food Technology Service operates an irradiation facility in Mulberry, approximately 15 minutes from Doyen's Lakeland headquarters. Its gamma radiation sterilization process has been extensively applied to packaging materials and is suited for the sterilization of devices. "Food Tech's ability to ensure rapid turnaround and on-time delivery is sure to attract interest from the medical market," says Doyen president Ray Johnson. "Its versatile, high-quality sterilization process is a natural extension of Doyen's contract packaging services."

Katherine Sweeny

Colorado MEDtech Offers Integrated Communications Technology

Colorado MEDtech Offers Integrated Communications Technology

Colorado MEDtech Inc. (Boulder, CO; www.cmed.com), a provider of medical technology outsourcing services and imaging products, announced that its RELA division has added medical device communications technology to its core competencies. The new technology enables medical devices and laboratory equipment to access clinical data via the Internet and to interface with a variety of hospital and laboratory information systems. It also allows instrument monitoring for service and maintenance. The technology can be designed into new medical products and systems or implemented into devices currently in use. Colorado MEDtech has agreements with Draeger Medical Inc. (Telford, PA; www.nad.com) and other medical device companies to develop specific product applications. According to company CEO Stephen K. Onody, the new technology "will extend the life of product portfolios as well as provide information access and system performance monitoring."

Katherine Sweeny

Tyco Adhesives Launches Custom Coating Division

Tyco Adhesives Launches Custom Coating Division

Turnkey coating services from Tyco Adhesives allow OEMs to outsource a challenging process.

Tyco Adhesives (Norwood, MA; www.tycoadhesives.com) has announced the inauguration of a custom coating division that will provide OEMs, converters, and suppliers with turnkey coating services. OEMs currently coating products in-house can now outsource what is traditionally a challenging process, according to the company, while leveraging the expertise of a 50-year-old tape and adhesives supplier.

Tyco Adhesives has experience in a broad range of applications from relatively simple to more complex, multiple-pass processes. Rubber, acrylic, and silicone-based adhesive systems are specialties.

The firm implements a complete product design program in order to optimize the conversion process and performance of the end product. Factors taken into account include customer specifications, endurance expectations, environmental conditions, processing parameters, and intended use of the product. A comprehensive test protocol and trial program allows a seamless transition to production, according to the company.—K.M.

Low-Temperature Process Developed for Titanium Nitride Production

Chemists at the University of Edinburgh in Scotland (www.ed.ac.uk) have developed a method to produce titanium nitride at lower temperatures than are currently the norm. The energy-efficient process may lead to a reduction in the production costs of medical implants, according to the researchers.

Titanium nitride is used to coat hip replacements and other implants as well as a host of nonmedical products. Production of the material typically requires temperatures between 800° and 900°C and costly high-vacuum equipment, because the rate of reaction between titanium and nitrogen is very slow at lower temperatures. An electrochemical process that uses liquid ammonia as a solvent has enabled Edinburgh's team of researchers to cause a reaction at temperatures ranging from –78° to 25°C. While electrochemical methods of production have been attempted before, Colin Pulham of the university's department of chemistry says the Edinburgh model is successful for two reasons: potassium amide has been added to the ammonia, and researchers have devised an innovative processing method.

"Most of the routes for [titanium nitride] production require high temperatures and expensive equipment, so there are significant energy and capital costs," says Pulham. "There are also drawbacks if you want to make precision tools, because the high temperatures cause them to deform. Our process offers an alternative low-temperature route for nitriding titanium-coated components, with no need for subsequent reheating," he adds.

The technology is available for licensing, and the university is currently seeking collaborative agreements with industrial partners. If you are interested in learning more, e-mail Ronald Kerr at the university's communications and public affairs office at communications.office@ed.ac.uk.

Norbert Sparrow

Medical Battery Maker Acquires Filter Technology

Medical Battery Maker Acquires Filter Technology

Through an acquisition agreement, a medical battery maker has gained the capability to include electromagnetic interference (EMI) filters on its components. Wilson Greatbatch Technologies (Clarence, NY; www.greatbatch.com) has purchased Maxwell Technologies, Sierra div. (Carson City, NV; www.maxwell.com), enabling it to develop EMI filters in-house that can help prevent pacemakers and other implantables from being adversely affected by cellular telephones, pagers, or other electronic devices. Sierra's technology will primarily be used by the Greatbatch-Hittman division, which makes feedthroughs used on pacemakers, implantable defibrillators, and other medical devices. Sierra will be renamed Greatbatch-Sierra. The acquisition will "allow us to offer a more complete line of engineered products," says Wilson Greatbatch president and CEO Edward F. Voboril. "While less than 25% of implantable medical devices have EMI protection today, we believe that the majority of such devices will have this feature over time," he adds.

Katherine Sweeny