Medical Device Link.

Originally Published EMDM March/April 2005

Manufacturing Innovations

Caitlin Cook and Norbert Sparrow

A water-jet-guided laser cutting system that can process tubing as small as 0.2 mm diam will be introduced this spring by Prejet Precision Techniques.

To state the obvious, manufacturers are engaged in a never-ending quest to cut costs and improve throughput. Medical device OEMs used to be somewhat sheltered from the penny pinching that is common currency in other industries, but the playing field has leveled considerably. In a harshly competitive global environment, companies don’t have the luxury to ignore new technologies that may allow them to automate a process or accelerate production. In this section, we highlight some equipment that has the potential to optimize production processes for med-tech firms.

Laser-Based Systems on the Cutting Edge

Laser-based processing is a mature technology that has proven to be extremely versatile and efficient on the shop floor. To press that point, two companies recently introduced laser-based cutters suitable for processing medical tubing, but each firm approached the application in a unique way.

181 Engineering (Sunnyvale, CA, USA; www.181engineering.com) figures that the name of its system—Tubezilla—says it all. Based on state-of-the-art motion control, laser technology, and computer automation, the laser-based cutter is designed for high-throughput production processes. The system was showcased at the recent Medical Design & Manufacturing (MD&M) West event in Anaheim, CA, USA.

Horizontal wire EDM equipment that automatically threads and machines with wires as small as 0.02 mm diam has been introduced by Makino GmbH to meet demand in the medical device and other industries for small, lightweight parts.

The unit’s rigid granite structure imparts acceleration and vibration isolation to support high production volumes. The tube cutter is designed for sustained operation with minimal operator intervention. A proprietary PLC-based fluid system enables unattended continuous operation. All fluid system functions are automated and self-monitoring. Filters can be replaced without interrupting the production cycle.

Tubing up to 6 ft in length and in diameters from 0.5 to 0.01 in., as well as parts as long as 24 in., can be processed on the machine. It can cut most common polymers and metals and alloys including stainless steel and nitinol. Variations of the system are available for ceramic and glass parts. Stents, biomedical devices, and drug-delivery systems are among the product groups targeted by the firm.

Catheter welding, tipping, and forming equipment from SEBRA Catheter Manufacturing Systems has been retooled to accommodate more materials, sizes, and forming dimensions than before.

Using laser equipment to cut tubing is a good idea, agrees Prejet Precision Techniques (Steffisburg, Switzerland; www.prejet.com). But the technology has its limits, adds the firm. This becomes especially apparent when tubing smaller than 0.5 mm diam is being processed. Prejet has developed a water-jet-guided laser cutting system that can precisely process tubing as small as 0.2 mm diam. The TCS-100 is scheduled to be launched this spring.

The primary advantage of this technology is the cut quality that can be achieved without damaging the inner diameter of the tubing, says the firm. The water-jet guidance system prevents the formation of miniature cracks and other heat-induced defects. The cut edge is practically free of burrs, and the debris is continuously evacuated by the water, ensuring that no deposits collect inside the tubing. Consequently, postprocessing is minimized and may even be eliminated.

The TCS-100 is specifically designed to accurately cut tubing between 0.2 and 7 mm diam. The system can be easily changed over from a water-jet-guided to a conventional laser cutting device.

Doing More with Less

A maker of moulding equipment and a developer of automation solutions for catheter production each have found novel ways to boost throughput. The companies’ engineers took a fresh look at their existing systems and asked the perennial question, What if? The surprising answers were exhibited at a couple of recent trade shows.

A stereolithography system from 3D Systems uses dual vats to process two differently coloured hearing aid shells simultaneously.

Even sober-minded visitors to the K in Düsseldorf, Germany, thought they were seeing double when they dropped by the stand of Milacron (Batavia, OH, USA; www. milacron.com). The firm exhibited a turning-cube stack system moulding a pair of parts from two materials, and then assembling and labelling them. The kicker? This was achieved using a single injection moulding unit.

The double-cube system, developed by Foboha Formenbau (Haslach, Germany; www.foboha.com), consists of two rotating cubes between the two halves of a mould. Three parting lines within the twin cubes allow multiple processes to occur at once. In sum, the unit is doing the work of two separate moulders. Assembly and labelling complete the process.

At the K, the secondary injection unit was mounted at a 45° angle on top of the moving platen. “This saves floor space,” notes Bob Hare, US general manager of Milacron. “More importantly, it reduces cycle times, because the injection nozzle stays mated to the hot runner system during clamp movement.”

The double-turning-stack system reportedly eliminates the costs associated with multiple injection machines, auxiliary equipment, labelling systems, and assembly machines. It can also generate savings in such areas as energy, labour, and maintenance.

Milacron’s K-TEC moulder is an ideal platform for the stack, according to the firm. An accumulator-based hydraulic system delivers constant flow rates to simultaneously drive the unit’s clamp, injection, and ejection sections. The basic machine can be combined with up to six injection units of different sizes for large-shot preforms and smaller secondary shots. Expanded tie-bar space and daylight options can accommodate large stack and cube moulds. And the machine’s control system is powerful enough to manage concurrent operation of all the hardware.

Machine Solutions Inc. (Flagstaff, AZ, USA; www.machinesolutions.org) is uniquely focused on automating labour-intensive processes within catheter manufacturing organizations. One of its newest machines, shown at MD&M West, is designed to allow the positioning and prereduction of marker bands on stents prior to swaging. This minimizes operator involvement.

In developing the SW1100, Machine Solutions engineers wondered if assigning double duty to a swaging die could eliminate the stage during which operators position and prereduce marker bands. They found that the die responsible for swaging could also be used to grip and position the marker bands.

The operator places the bands on the shaft, which is inserted into the machine. The machine then positions and swages the marker bands within ±0.002 in. of preset parameters.

Suitable for high-volume manufacturing, the SW1100 can incorporate automated catheter magazine–handling, vision, and thermal control systems. Electrophysiology products, stents, and surgical tools will benefit from this innovation, says the firm.
A maker of catheter welding, tipping, and forming systems also introduced improvements in its product range at MD&M West. PIRF II and PIRF III systems from SEBRA Catheter Manufacturing Systems (Tucson, AZ, USA; www.sebra.com) now work with a broader range of materials, sizes, and forming dimensions than before.

Each system can be combined with various tipping, welding, and forming moulds. The firm anticipates that improvements on the semiautomated process will lead to reduced assembly costs and improved quality control.

Suitable for forming small-profile catheters, CE-marked PIRF II systems concentrate heat in bands that can be less than 1 mm wide. The process reportedly results in a smooth surface finish and strong welds, even when processing materials with significant differences in durometer. PIRF III systems are designed for multiple-part tipping.

Along with diversified production capabilities, both systems are offered with front-panel programming.

EDM Equipment Accommodates Micrometre-Size Wires

One good turn deserves another: Milacron’s double-turning-cube stack injection moulding system produces two parts from two materials, and then assembles and labels them.

The extreme accuracy required to machine micrometre- and nanometre-size parts prompted a company to develop complementary horizontal wire EDM equipment. The system automatically threads and machines using wires as small as 0.02 mm diam. Makino GmbH (Hamburg, Germany; www.makino.com) exhibited the machine at MD&M West.

The UPJ-2 can automatically thread the thin-diameter wire through a 0.07-mm-diam start hole with a 0.15-mm pitch. The use of dielectric fluid helps to minimize spark gap and to enhance the workpiece’s finish.

The machine is housed in a temperature-controlled environment. Makino’s Thermal Guard system maintains the interior temperature to within 0.5°C. This helps to ensure that high-accuracy machining is maintained even during extended periods of operation.

X-, y-, and z-axis travel is 200 ¥ 200 ¥ 60 mm, while u- and v-axis travel is specified at ±10 mm. A 50-nm-scale feedback system is standard in the x-, y-, u-, and v-axes to enhance positioning accuracy and facilitate micromachining.

A v-type wire guide is used in lieu of a round guide to optimize threading accuracy. The machine comes equipped with a Windows CE operating system, 15-in. liquid crystal display, and an Ethernet interface.

An automatic work changer and core removal unit are available as options. The core removal unit, notes the firm, increases productivity by automatically cutting out the cores following machining.

The UPJ-2 is well suited for the medical device and other industries producing ever smaller and lighter parts with greater functionality.

SLA Speeds-Up Tempo for Production of Hearing Aid Parts

Swaging equipment from Machine Solutions semiautomates the positioning and prereduction of marker bands on stents prior to swaging.

Diversifying production capabilities without sacrificing rapid output would be music to any medical device manufacturer’s ears. A stereolithography (SLA) system may hit the right note by allowing OEMs to use one system to make hearing aid shells from two materials at the same time.

Offered by 3D Systems Europe Ltd. (Hemel Hempstead, Herts, UK; www.3dsystems.com), the Viper HA SLA system uses dual vats to process two differently coloured hearing aid shells simultaneously. The manufacturer touts the platform’s ability to accelerate production batch cycles while enabling its customers to diversify product designs.

The system’s quick-release elevator arms eliminate the need for component cleaning between vat changes. A specially designed material-handling cart allows a single operator to hoist, drain, and filter vat contents. The cart also facilitates rapid vat changeovers.

Integrated production software streamlines part preparation and build setup. The system uses a 354.7-nm-wavelength laser that produces up to 100 mW of power at each vat. The system is designed for use with Dreve Fototec SL materials and 3Shape a/s software.

CEO and president Abe Reichental remarks that the Viper is the first stereolithography manufacturing system that uses dual vats. “Customers are able to produce in multiple colours, and to increase their productivity by building a full set of hearing aid shells in one build, instead of two,” he says. This enhances productivity for both large and small production facilities, adds Reichental.

Copyright ©2005 European Medical Device Manufacturer