Medical Device Link.

Originally Published EMDM November 2003

Product Update

Developments in Tube-Processing Equipment

Noncontact lumen-locating technology and hoop-force measurement equipment take out some of the guesswork
for device OEMs.

Laura Angela Bagnetto

The manufacture of medical-grade tubing and associated assemblies is not a simple matter. Fortunately, equipment suppliers continue to find ways to automate, and in the process simplify, production and testing procedures. A drilling system, for example, accurately senses and positions lumens for hole placement. An all-in-one assembly bench for tubing sets integrates tasks that are typically performed at different workstations. And a company that develops catheter- and stent-testing equipment has introduced a device that measures the hoop force of stents and stent grafts. Additional products and services related to tubing and tube-processing equipment are profiled in the company descriptions that appear in the following pages of this section.

Smarter Drilling

A workstation from Tecnoideal S.r.l. is suited for the assembly and testing of complex blood tubing sets.

A company has introduced a noncontact lumen-locating technology to its line of automated hole-making systems. It was developed by Technical Innovations (Brazoria, TX, USA) in direct response to customer requests. “Device makers were having trouble processing multilumen tubing,” says CEO Gary Cordell. “It was often a very tedious process to identify, orient and punch the appropriate lumen, particularly in a multiple-hole pattern.”

The technology combines a noncontact proximity sensor and proprietary circuitry and software. A stainless-steel or nitinol mandrel is inserted into a nontarget lumen in a multilumen tube. The system senses the mandrel and precisely locates the targeted lumen for hole placement, regardless of axial twists created by the extrusion process.

Typical applications include closed-end and multilumen catheters that are difficult or impossible to accurately orient for hole making from the distal or proximal end of the tube.

The technology is available with the company’s automated Smart Driller CL and Smart Puncher CL units.

Blood Work

An all-in-one assembly bench is offered as an alternative to the fragmentary process of assembling and testing blood tubing sets and related disposables. The Ergoline System 2 from Tecnoideal S.r.l. (Mirandola, MO, Italy) accommodates tubing in multiple sizes, lengths, and diameters, and it is suited for the assembly of complex tubing configurations involving several components and processing steps. Multiple procedures are not an issue, according to marketing director Roberta Borsari. In fact, she notes, “this system is unique because one operator can take the product from start to finish. It does not require a number of people at different stations, as is often the case.”

Equipment designed to measure the radial expansion force of stents has been introduced by Machine Solutions Inc.

The Ergoline System 2 bench incorporates a Twincut machine, which automatically cuts tubing in preparation for final assembly. Two different types of tubing can be loaded and cut to any length, in any programmed sequence. “It can make 60 sets per hour,” says Borsari, “which is the standard for complex tubing sets, such as venous or arterial lines.” For simpler assemblies, throughput can attain 100 pieces per hour.

The bench also includes a rotating distributor with 12 stainless-steel trays. The trays are preloaded with the components needed in the order of assembly. A DS2 solvent dispenser bonds the tubing to the components, and a Windy machine, operated by means of a foot switch, coils the product.
The system comes with a calibrated leak-test machine to ensure product quality. While the P-Test Plus performs a 100% pressure decay test of the finished product, another blood tubing set can be assembled on the front end of the unit.

Tecnoideal is currently developing a machine that automatically cuts tubing from a reel at the required length, coils it, and wraps the product with cohesive tape. “The Cut-Coil-Band machine is currently in the prototype stage,” says Borsari.

Measuring Radial Expansion

To be approved for use, stent products must be shown to exert sufficient force to achieve their clinical objectives. Machine Solutions Inc. (MSI; Flagstaff, AZ, USA) has developed radial-expansion force-measurement equipment to measure the hoop force of stents and stent grafts during expansion and compression. The RX500 radial force gauge integrates a proprietary segmental compression mechanism that is specifically designed to provide a low- friction testing environment.

“Hoop force is the outward force that originates at the center of a tube and is equal in all directions,” says global marketing director James Kasprzyk. “In the case of balloon expandable stents, it is the force exerted on a blood vessel. If a stent product does not produce enough outward force on the vessel, it may slip, provide a path for leakage, or collapse under pressure.”

The RX500 uses a linear force transducer to maintain resolution at hoop-force levels from 0 to 18 N. Hysteresis, hoop strength, and creep are measured and recorded as the product is cycled through programmed open-and-close diameters by means of a microstepping linear actuator.

“With decreased setup time and simplified data acquisition, the RX500 has increased accuracy and resolution,” says Kasprzyk. The data strings are set up for easy export into Excel spreadsheets.

UTI Corp.

Nitinol tubing is fabricated by means of a drawing process that yields better control of wall thicknesses than conventional methods. The process results in stents with more-uniform radial stress and catheters with enhanced torque transmission, according to UTI Corp. (Collegeville, PA, USA). For stent-sized tubing, wall thickness can be measured directly and reported statistically. The tube drawing process enables the production of tubing with shaped cross sections in lengths up to 20 ft. Shaped tubing is superior to round tubing in a number of applications, according to UTI.

For example, when joining wires side by side using a nitinol crimp ring, drawing an oval tube eliminates the need to flatten cut pieces. In catheter applications, adds the firm, nitinol tubes with a shaped cross section can be used to tailor section modulus in different bending directions.

UTI supplies two grades of nitinol: high-strength SE 15C and standard SE 30C, which operates most effectively at or above room temperature.

Gillard Cutting Technology

Engineered for precision medical device applications, a cutting machine processes small-bore tubing with outer diameters from 0.3 mm. Cutting small tubing can be quite difficult, says Chris Gillard, marketing director for Gillard Cutting Technology (Tewkesbury, Glos, UK). The tubes need to be fed into the machine and cut at a high speed to ensure optimum product output, he notes. Gillard’s Servo-Torq machines meet this challenge by using digitally controlled ac brushless servomotors to activate a flying-knife rotary cutting action. “By using three servomotors that are adjusted at the same time, the process is perfectly synchronized,” says Gillard.

The Servo-Torq is available with 30- and 50-mm cutting capacities. It is suited for cutting all manner of medical tubing, including bubble and tapered products.

Machine Solutions Inc. 

A company has developed a machine to measure the hoop force of stent and stent graft products during expansion and compression. Developed by Machine Solutions Inc. (MSI; Flagstaff, AZ, USA) the RX500 radial force gauge “is designed for self-expanding stents, balloon-expandable stents, and embolic filters,” says project engineer Melissa Lachowitzer. In addition to hoop strength, the device measures and records hysteresis and creep in a low-friction testing environment. The machine may have other applications, as well, adds Lachowitzer. One possibility “is determining how much radial force it takes to compress a thin-walled tube.”

The RX500 is the latest in a line of equipment developed by MSI for stent crimping, swaging, balloon processing, and catheter testing. The company’s segmental compression technology reportedly results in reduced crimped-stent and folded-balloon profiles, improved stent retention, shorter cycle times, and increased yields.

The firm recently opened a showroom in Santa Clara, CA, USA, near San Francisco.

Tecnoideal S.r.l.

A range of tube-processing equipment including cutting machines, adhesive dispensers, leak testers, and automated and custom assembly systems is offered by a company with extensive design and development experience.

The Rotocut from Tecnoideal S.r.l. (Mirandola, MO, Italy) is an automatic cutting machine designed for use on extrusion lines. Tubing can be cut in consistent lengths, at speeds up to 1400 cuts per minute. The unit is recommended for cutting plasticized PVC and other medical-grade materials where quality is paramount. An optional blade-wetting unit for use with silicone and EVA products is available. A conveyor system that collects and bundles the cut tubing can be supplied.

The company also supplies the Ergoline System 2 assembly bench for medical tubing sets. “This system is unique in that it allows a single operator to assemble and test the finished product,” says marketing manager Roberta Borsari. It incorporates a cutting unit, solvent dispenser, automatic coiler, and leak tester. See the feature article on page 58 for more information about this equipment.

Technical Innovations

A company has introduced enhancements to its automated hole-making systems and now offers contract services in addition to production equipment. Noncontact lumen-locating and hole-plug-detection technologies from Technical Innovations (Brazoria, TX, USA) are available with its Smart Driller CL and Smart Puncher CL machines.

To assist device makers in disposing of hole plugs, the company has developed a technology that detects, counts, and collects plugs during each hole-drilling or hole-punching cycle. After drilling or punching, the plug is ejected from the cutting tool by a fixed ejector pin and it is vacuumed up a tube. A light curtain inside the tube confirms the presence of the plug. If the plug count differs from the preset pattern hole count, the system issues an alert. The system is capable of detecting and counting plugs as small as 0.020 in.

For the processing of multilumen catheters, the company has developed an automated noncontact process for locating a desired lumen prior to drilling, skiving, or punching operations. The technology is described in the feature article on page 58.

Technical Innovations has announced that it will provide customers with contract hole-making services. The firm recently expanded its facility to accommodate demand both for its outsourcing services and hole-making equipment among medical device OEMs, according to president Gail Brinson.

GlobalMed Inc.

Bespoke corrugated and collapsible tubing is supplied for anaesthesia and respiratory applications. GlobalMed Inc. (Trenton, ON, Canada) works with clients’ R&D departments so the tubing “fits the application,” not the other way around, says Kevin Norris, vice president of marketing. “This cuts costs and saves time in an environment where [these] are key factors in the success of new products.”

The tubing can be modified in diameter, length, colour, weight, and flexibility to suit customer requirements. The company’s products are a core component in a range of drainage procedures.

GlobalMed also offers injection-moulded fittings and contract manufacturing and assembly services. 

NewAge Industries Inc.

Medical-grade silicone tubing and hose is supplied for dialysis machines, vaccine transfer, blood or biological fluid handling, and other applications. NewAge Industries (Southampton, PA, USA) manufactures nonreinforced and braid-reinforced hose in a Class 1000 cleanroom. Peroxide- and platinum-cured tubing is available for high-purity applications.

The silicone elastomers contain nontoxic ingredients in accordance with USP Class VI requirements. The tubing and hose resist the adherence of particles and will not support bacterial growth. The products are soft, flexible, and contain no plasticizers; sizes range from 3.175 to 25.40 mm ID.

NewAge Industries also offers Suprene thermoplastic rubber tubing with flex-fatigue resistance for use in applications such as peristaltic pumps. The autoclavable material is available in 64 and 80 Shore A durometers and 3.175 to 19.05 mm ID. It withstands temperatures from –51° to 135°C.

Tekni-Plex

Flexible tubing is suited for use as a replacement for silicone tubing in peristaltic pumps. Tests conducted at Ghent University in Belgium showed that Plasmed SR tubing, which has mechanical properties similar to silicone, outperformed PVC and silicone in a number of areas. Supplied by Tekni-Plex Europe N.V. (Erembodegem, Belgium) the tubing features low spallation and a long pump life and it has low protein residue. It is available in 52 and 60 Shore A versions.

Tekni-Plex also offers tubing for use in IV and other disposable products. The company formulates PVC compounds for customers that require materials with a phthalate-free plasticizer.

Gimac

A coextrusion line less than 3 m long is available for the production of small, calibrated tubes measuring 0.4 to 4 mm OD and made of rigid or soft materials. Gimac (Castronno, VA, Italy) has designed the system for medical and pharmaceutical applications. Tubing can have as many as three layers and radiopaque striping. The line can be set for production output of 0.1–4.5 kg/hr. The machines composing it can be delivered singly or with a table support.

Chief components of the coextrusion line are three microextruders equipped with a 1.1-kW ac motor with encoder feedback and featuring a maximum screw speed of 100 rpm, along with an extrusion head for producing tubes of 1, 2, or 3 layers. Other elements include a vacuum calibrator with cooling unit and water recirculation tank, a laser gauge for diameter control, a haul-off with a maximum speed of 84 m/min, and a control cabinet. The line features an Allen Bradley programmable logic controller and is operated via a personal computer with touch screen. The extruders and haul-off are controlled by an Allen Bradley vectorial inverter.

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