EQUIPMENT NEWS
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Single-screw extruders operate continuously
Single-screw extruders are manufactured and supplied by a young company that is the heir of a technology enterprise that has been in business for 35 years. Norolex AB (Ödåkra, Sweden) specializes in producing extruders in screw sizes from 20 to 60 mm that are targeted primarily at the profile extrusion industry. Its customers are mainly extruders of pipes, hoses, profiles, coatings, and coextrusions, many of them in the medical and dental device industries.
Designed and built for continuous operation under difficult conditions, the extruders are robust, reliable, and easy to handle. The manufacturer offers a line of haul-offs and is able to design special single-screw extruders on a custom basis.
Formerly organized under the name Revitech, the company cooperates with another company, Svenska Norol Plastmaskiner AB, from which it is descended and which offers a range of extrusion machines up to 150 mm in size. Its principal market now is northern Europe, though it operates and sells worldwide and is planning to widen its arena of competition.
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Tabletop crosshead extruders process medical plastics, silicone, and rubber
A line of compact tabletop medical and industrial tubing extruders is designed for use with crosshead dies in the production of single-lumen, multilumen, and coextruded multilayer and striped tubing. Available in screw sizes from 6 to 32 mm, these Yellow Jacket extruders from Wayne Machine & Die Co. (Totowa, NJ, USA) feature heavy-duty double-reduction gearboxes and one-piece bimetallic lined barrels with integral bimetallic lined feed areas. Special screws are available for both common and difficult-to-process tubing materials, including polyurethane, PVC, and nylon.
These extruders process a wide variety of medical plastics. In addition, models that can handle silicone and rubber are available. Further, upgrades to allow high-temperature and highly corrosive materials such as Teflon FEP, ETFE, ETCFE, and PFA to be processed can be provided as options.
The manufacturer produces straight and crosshead dies, water troughs, vacuum tanks, pullers, cutters, and winders, as well as extruders. It offers complete turnkey tubing systems, too. The company offers equipment custom built to specifications and carrying the CE mark.
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Vacuum tank enhances tube-sizing precision
Tube-processing technology for demanding medical applications is the specialty of a supplier of a full line of extrusion and downstream equipment that includes options designed to enable processors to maintain high levels of cleanliness and accuracy. For example, for precision contact or noncontact sizing of extruded tubes, Davis-Standard Ltd. (Luton, UK) offers the DST high-technology vacuum sizing tank. This accessory provides stable vacuum levels to 2.5 mmH2O throughout the vacuum range, a degree of precision that allows for demanding inner- and outer-diameter dimensions and enables sticky materials such as flexible PVC and urethane to be sized.
Other benefits of the tank design are the inclusion of a high-output circulation pump in the lower tank and chamber, a vacuum set point regulated by a closed-loop control system, an air-from-water separation system, noise reduction features, and ergonomic advantages; the layout makes the system easy for operators to use and access. The tank is well suited for straight tube and small pipes, for bump tubing, and for multilumen applications.
With straight tube and small pipes, the tank can improve roundness and outside-diameter tolerances whether operated in contact or noncontact mode. For bump tubing, vacuum sizing keeps the bump portion of the tube round without relying solely on the internal air supply. And for the production of multilumen tubing, vacuum sizing makes unnecessary the use of internal air supplies to keep outside walls consistent from lumen to lumen.
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Extrusion-melt transducer for medical tubing has no toxic or liquid fillers
An extrusion pressure transducer features an integral J-type thermocouple for dual pressure and temperature measurement. Available from Terwin Instruments Ltd. (Bottesford, Notts, UK), the Model 2076J transducer uses a patented twin-tube system that provides automatic zero correction to the pressure signal when process temperature fluctuates. The design is free of toxic or liquid fillers such as mercury, sodium, potassium, and diathermic oils. Available pressure ranges are 0–35 bar through 0–2000 bar, and accuracy is within 0.5% of the selected range.
Thermocouple and pressure connections are achieved via an eight-pin connector that makes separate thermocouple connectors and extension leads unnecessary. The transducer is supplied with an eight-core high-temperature-shielded cable that also incorporates the necessary leads for the J-type thermocouple.
In order to accommodate every size of extruder, the manufacturer supplies transducers with stem lengths of 92, 152, 228, and 305 mm. All of these are fitted with an abrasion- and corrosion-resistant DiHard diaphragm that withstands temperatures to 450°C. The electrical termination head is rated for 200°C.
Automatic machines cut round tubing accurately without crushing
A family of automatic tubing and wire cutters features high levels of cut-length accuracy and cut perpendicularity. The precision-action WC601 series of cutters from The Eraser Company, Inc. (Syracuse, NY, USA), cut flexible tubing as large as 28.5 mm OD into lengths ranging from 2.54 mm up to 99,999.99 mm. They are capable of holding to very tight specifications such as are required in medical device applications.
Each unit has a batching feature, offers five feed rates for production flexibility, and is easy to set up and operate. The cutters employ a self-centring belt feed mechanism to achieve a very high degree of length accuracy and to avoid crushing the tubing material. They consistently produce straight cuts that are perpendicular to the tube axis.
The manufacturer, which produces a wide range of tube-processing equipment, offers a free sample analysis. Customers send the company a 5- to 10-ft sample of the material to be processed, and the company will recommend the product in its line that is best suited for handling the cutting or other processing requirement.
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Tubing cutter puts clean edges on thin-walled, small-diameter tube pieces
An automatic tube-cutting machine is designed specifically to cut plastic tubes having a small outside diameter and thin walls. BW-TEC GmbH (Höri, Switzerland) has given the machine, designated 2001-030, a special cutting movement and a cutting edge of minimal thickness in order to achieve cleanly cut, burr-free edges on rectilinear sections. The manufacturer has ensured that the tubing cutter is highly efficient and economical by using standard 0.10- to 0.15-mm cutting edges. A new vacuum system enables the user to cut tubing 0.2 to 5 mm in diameter into lengths of 1–2000 mm and have all the cut pieces collected conveniently in a container.
This tube-cutting machine can process as many as four tubes simultaneously, with a cutting tolerance of 1%. It operates at tube feed speeds of 10–470 mm/sec, producing cut lengths up to 10 mm long at a rate of 400 pieces per minute and up to 200 mm long at 160 pieces per minute. Cut lengths and process speeds are set via a programmable logic controller with user interface and display. Optical sensors count pieces and monitor performance.
The 2001-030 has a pressure controller that adjusts cutting pressure between 0.15 and 0.6 MPa. Offered with removable cutting dies in standard diameters of 2.0, 3.0, 4.0, and 5.2 mm, it can be supplied optionally with additional cutter diameters, as well as an axial cutting head. Overall machine dimensions are 1000 × 260 × 220 mm.
Tube-set coiling machine is designed for high speed with safety
A coiling machine for use in the manufacture and assembly of tubing-based medical products such as catheters and IV sets has been redesigned with new features. The Mini-Winder from S-Y-M Products Co. (Stamford, CT, USA) can coil and package products several times faster than other technologies while yet minimizing the risk of injury to operators’ hands and wrists. The compact tubing-set coiler comes equipped with hand and foot controls and is positioned on a work surface for operation. Manufactured for use in a clean environment, it has product-contacting surfaces that are all of stainless steel or high-density plastic.
The machine operates as follows: The user places a length of tubing on the mandrel, which rotates exactly the number of times necessary to complete the coil. The coiling speed, size of coil, number of rotations, direction of rotation, height of the mandrel, and many other parameters are adjustable. Once the coiling process is finished, the mandrel retracts, at which point the operator can slide the coiled tubing set into a package without having to lift it.
