High-efficiency medical tubing lines

The global medical industry is now facing a major challenge, with the Covid-19 declared as pandemic. The situation calls for urgent medical services to be delivered to affected countries and regions around the world. In this aspect, the production of medical supplies is being rushed to meet rising demand. 

 

Prior to the spread of the coronavirus, the global medical tubing market size is already expected to reach $11.9 billion by 2025, based on a CAGR of 9.2% as estimated by Grand View Research, Inc. The report cites increase in health expenditure by individuals and rising emphasis by the government as factors that stimulate market growth over the forecast period. In addition, the fast ageing population and rising number of people looking for high-quality life are expected to offer opportunities to the manufacturers that innovate and produce a diverse range of products, as well as the growth in chronic disease incidences across the globe.  

 

The demand for medical tubes in wound therapy, stent tubes, and implant-grade tubes owing to their cost effectiveness is anticipated to boost market growth. Growing consciousness regarding hospital-acquired infections coupled with rising concerns related to the spread of infections, is expected to surge the demand for single-use or disposable healthcare devices. Increasing strategic alliances among the medical device industry players is anticipated to propel the demand for disposables, thereby driving the medical tubing market. Asia Pacific is anticipated to witness a CAGR of 10.6% in terms of revenue over the forecast period owing to rise in advancements in terms of medical device regulations and technologies in countries such as China, Japan, India, and South Korea

 

Latest technologies in IV tube extrusion 

Conair Group, together with technology partners Davis-Standard and Zumbach Electronics, demonstrated the production of extruded 4.5-mm (0.18-inch) thermoplastic elastomer (TPE) medical tubing and ABS 1.7mm 3D-printing filament at MD&M West 2020. The demonstrated line highlighted the latest technology in extrusion, vacuum sizing/cooling, gauging, coiling, conveying, and quality control.  

 

A 2-inch “Super Blue” Davis-Standard extruder, equipped with a Touch Panel Control is at the head of the IV tubing production line. Its output is supported by Conair upstream and downstream equipment, with downstream measurement and monitoring provided by Zumbach Electronics. The TPC integrates all these downstream inputs for complete line control through a single HMI. The demonstration line can deliver production rates up to 400 ft/minute.  On the first two days of the exhibition, the line was demonstrated producing 4.5mm IV tube made of clear thermoplastic elastomer from the Teknor Apex Medalist® line. TPE is a popular choice for medical tube applications because it offers good weldability, enhanced gamma stability, and excellent clarity, flexibility and kink resistance. 

 

                                          The Conair HTMP multi-pass vacuum-sizing/cooling tank  

 

The TPE resin is delivered to the extruder feed throat through a self-contained Conair Access™ Series AL-2 mini-loader. After processing through the extruder, tubing leaves the die and immediately enters the Conair HTMP multi-pass tank. The tank is the first of four MedLine® auxiliaries put on display by Conair: all are medical-grade variants of proven Conair auxiliary equipment designs that are specially sized, configured, documented, and supported for cleanroom applications. 

 

“Floor space in any manufacturing plant is costly,” according to Ernie Preiato, VP – Extrusion Sales, “and even more so in a cleanroom environment. Considering our multi-pass tanks occupy only about a third of the space a full-length, single-pass tank requires, the savings and convenience are considerable.”

 

For the first time, the space-saving Conair HTMP multi-pass vacuum-sizing/cooling tank and the ATC Series coiler were demonstrated. Instead of making a single pass through a long tank, the extrudate follows a Z-shaped path so that the compact, 12-ft-long HTMP tank provides cooling time equivalent to a 30-ft tank while fitting neatly into the 20 x 30-ft Conair tradeshow booth. The ATC Series coiler provides tensionless winding of extruded tubing and filament to prevent damage, and is equipped with an automatic coil-isolation safety feature that prevents user access to moving coils.   

 

The HTMP tank uses a series of motorised sheaves to gently pull extrudate through cooling water, starting with a 6-ft vacuum chamber that creates a positive differential in air pressure within the extruded tube. This slight outward pressure helps stabilise tube dimensions before additional cooling passes while preventing any “drool” of cooling water out of the tank’s feed opening that could mar the surface finish of the product. At the same time, a pair of Zumbach Electronics ultrasonic gauges – one each near the tank entrance and exit – continuously monitor and report changes in tube wall thickness on a control screen as the tubing cools. Further downstream from the tank, a Zumbach 3-axis OD laser gauge provides not only closed-loop dimensional control, but also displays the tube profile for concentricity adjustments. Together, data from the ultrasonic and laser gauges are used to regulate puller speed and cooling-tank vacuum to maintain critical tube dimensions over the production run. 

 

Because precise temperature control is also essential to proper extrudate drawdown and sizing, the HTMP vacuum cooling tank is served by a MedLine Thermolator® temperature control unit (TCU) and a Conair EP1A-02 (two-ton) portable air-cooled chiller. 

 

 

The finished extrudate (tube or filament) then moves through a Conair MedLine Pinch Roll puller. The programmable, dual-servo precision puller is commonly used on high-speed medical tube lines that feed their output onto coilers. In this case, the coiler is a Conair MedLine ATC Series coiler. Its floor-mounted ultrasonic loop sensor monitors the incoming product, automatically adjusting coil speed and traverse motion to wind product smoothly into a military wrap, without the friction or tension that can distort delicate extruded products. As one coil is filled, the dual-spindle ATC Series automatically adjusts, rotating the full coil out of the way, cutting the extrudate, then rapidly transferring it to the empty spindle to continue winding. The unit’s automatic coil-isolation feature locks out access during coil transition, then actuates upper and lower safety gates that isolate the actively winding spindle, enabling users to safely access and remove full coils on the other side of the cabinet. 

 

Like the other Conair MedLine auxiliaries, the coiler is also outfitted in RAL 9000 medical paint on non-contact surfaces, with stainless steel on any product-contact surfaces. It is equipped with a full guarding package that includes an aluminum frame and clear viewing doors that interlock for safety.

 

Shifting to filament production 

Conair and its partners shifted the extrusion line over to production of ABS 1.7mm 3D filament for the show’s final day. The demonstration highlighted the dramatic growth of 3D printing as a manufacturing process, answering the questions of many manufacturers who are evaluating the development of their own filament extrusion lines as a way to increase control over filament quality, minimise pre-conditioning requirements, and control costs.   

 

Changing the extrusion line to filament production is straightforward:  the only hardware changes involve installing a filament extrusion die and a “pre-skinner,” a non-contact sizing chamber, at the entrance of the HTMP multi-pass vacuum sizing tank. The pre-skinner, engineered at Conair’s Extrusion Laboratory in Pinconning, MI, is a water-filled chamber used to pre-cool and “skin” the surface of the filament extrusion before it comes into contact with calibration sleeves in the vacuum cooling tank. Without the benefit of pre-skinning, the hot filament could repeatedly stick and release on the calibration sleeves, resulting in “chatter” marks that mar the dimensional consistency and surface finish of the extruded product.