Medical Device Link.

Originally Published EMDM March/April 2003

Equipment News

Hose vulcanization line minimizes deformation risk

A vulcanization line for the production of hoses from silicone rubber consists of vertical and horizontal sections and is designed to overcome problems of deformation to which silicone hoses are subject when standard horizontal vulcanization lines are used. With the line from Troester GmbH & Co. KG (Hannover, Germany), hoses, upon being extruded, pass through a vertical prevulcanization section that stabilizes their shape. Before they enter the subsequent horizontal vulcanization section the hoses have already been cured enough to ensure that deformation can no longer occur.

With a combination system consisting of a GS 60/k-10 D main extruder, a secondary GS 30/k-10 D extruder, and a crosshead, hoses can be produced from two different types of silicone or can be given a colour stripe. Extruded product passes through a vertical infrared heating section as hot as 650°C, being guided downward and then up again in a controlled loop. The remainder of the line is a horizontal infrared channel with radiation heating from above and below at a maximum of 650°C, followed by a special conveyor belt that also can be heated to as much as 650°C.
Maximum throughput depends on the extrusion cross section and the compound. The main extruder in the sample system described can handle a maximum volume of 60–100 kg/hr, and the secondary extruder about 5–10 kg/hr, with a hose diameter of no more than about 20 mm.

Laser processing of thin-tube exteriors does not affect inside wall

Because the metal tubing used in some medical products is getting smaller and smaller, the challenge of processing the outside wall without affecting the inner wall increasingly is being met through laser technology. The StarCut Tube laser system from Rofin/Baasel Lasertech (Starnberg, Germany) is suitable for fully automatic processing of tubes 0.2 to 10 mm in diameter. The turnkey system employs a pulsed Nd:YAG laser with repetition rates up to 4000 Hz, and can process such materials as stainless steel, cobalt-chromium alloys, nitinol, tantalum, platinum, and niobium.

The laser is able to cut surgical needles because it is not limited to tangential cutting angles and can operate on very small tubes down to 170 µm in diameter. It produces a burr-free cut with extremely sharp edges and a minimal heat-affected zone.

The laser manufacturer specializes in highly accurate laser cutting and ablation systems that can realize microscale designs with clean cuts free of dross and oxides. Complete systems as well as laser sources are supplied to suit specific requirements. Applications include catheter treatment, cutting of stents and other vascular implants, and plastics welding of, for example, multilumen balloon tubing.

Cleanroom tester checks multilumen catheters for leaks, occlusions 

A range of automatic leak and occlusion test systems is designed to accommodate multilumen and other types of catheters. Available from Optimeasure Ltd. (Ampthill, Beds, UK), the ergonomically engineered equipment is easy to use. It is suited for the production cleanroom and makes possible rapid 100% testing of manufactured devices. Sealing tools are offered that can accept any size of catheter whether in single- or multilumen format, including stent devices, with air pressures up to 35 bar.

The new manufacturing company is staffed by engineers experienced in the application and support of advanced test equipment for medical device and pharmaceutical manufacturers.

One source offers complete technology for cannula manufacture

A specialist in the development and production of machinery for the manufacture of cannulae offers more than 30 machines along with accessories, providing all of the technology necessary to complete a production line. It also provides training of customer personnel and instruction in the capabilities of the equipment. Justur spol. (Stara Tura, Slovakia) supplies production equipment for welding tubes from stainless-steel tape, drawing tubes by means of a floating mandrel, straightening and cutting tubes, deburring cut ends, grinding, and cleaning tubes after grinding and before assembly.

One line can be used to mass-produce welded thin-wall tubes for needles by roll-bending calibrated tape and performing further welding using a nonconsumable electrode without filler. The takeoff unit winds the tubing onto a reel. Tubes up to 1000 m long can be manufactured without interruption or defects and with strict observance of preset parameters.

A pair of machines constitutes a tube-drawing bench. The TST uses a floating mandrel to calibrate the wall thickness of thin-wall longitudinally welded tubes. Tubing unwound from the reel passes through the die chamber to the drawing drum and is wound again on the reel, all under control based on the constant measurement of tensile force. The TSD 1 performs hollow drawing of thin-wall tubes after their wall thickness has been calibrated to the final dimension.

CNC needle-tip grinder produces multifaceted cutting edges

A CNC-controlled creep-feed surface and profile grinding machine provides fully automatic production of multifaceted cutting edges on medical needle tips. Manufactured by Jones & Shipman International (Leicester, UK), the Dominator, with GE Fanuc control, can put two, three, or more facets on the cutting tips of needles produced from tubes 0.27 to 4.5 mm in diameter and 50 to 400 mm long. The workpieces are held in appropriate quantities according to size in removable cassettes. Each fixture can hold and grind any programmed size of needle; 60 3-mm-diam needles with three facets can be ground in 10 seconds per needle, for example.

The small-footprint grinder features high rigidity and easy programmability via Windows-based software. The z-axis that traverses the needles and the x- and y-axes that are used to form the facets are independently programmable. The software that enables automatic operation is supplied with macros to generate custom tip forms and can accommodate the insertion of additional macros for nonstandard tip geometry. It includes compensation for wheel dressing, calculation of lateral movement in relation to needle diameter, and an interface facilitating needle selection based on user-generated specifications. Fourth-axis control software for complex parts may be incorporated.

Ultrasonic catheter punching produces smoother eyes

While the mechanical punching of eyes in catheter tubing generates orifices that can have sharp edges capable of harming the patient upon catheter insertion, an ultrasonic drainage and suction catheter manufacturing process can eliminate this problem. Ultrasonic equipment offered by Kahle Europea S.p.A. (Caravaggio, BG, Italy) forms a radius on the edges of the eye that removes the risk of rupturing tissue when the catheter is introduced. It also ensures that ellipses are formed accurately, which prevents flow through the eyelets from being turbulent. The assembly systems available from the specialty manufacturer further assure catheter tubing quality by including total on-line inspection and a patented tip-forming process.

Heated tube expander makes vinyl and Teflon products tractable

A tube expander specially designed for difficult-to-expand tubing materials such as vinyl and Teflon employs a heated mandrel to soften the tubing enough to allow expansion without danger of splitting the tube ends. The tip of the mandrel of the Model 1200-B, available from Lakeview Equipment Inc. (Northbrook, IL, USA), can be heat-controlled up to a temperature of 300°F. Although the machine is particularly well suited to vinyl and Teflon, it can also be used to expand polyurethane and polyethylene tubing. 

Two Teflon-coated mandrels are supplied with each unit and are custom-made to meet the exact size and configuration requirements of the customer’s application. The tube expander runs on 120 V ac and has UL-listed components. The company also supplies tubing cutters, pneumatic presses, and related equipment.

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