Sep 19, 2012: High Five: American Kuhne Conquers Tight Tolerance PEEK Extrusion
Leading US-based extrusion machinery supplier American Kuhne (AK) has successfully extruded PEEK tubing using a vertically upward extrusion line. There is a patent pending on the technology. In a series of experiments, the company has found that by passing tubing through an oven placed above the die head, it can be annealed and the outer diameter and ovality can be controlled precisely. The outer diameter can be kept to a tolerance of ±0.0007” (0.18 mm) while the ovality to less than 0.001” (0.25 mm). The process of annealing gives PEEK the time to crystallise uniformly as it cools, giving optimum physical properties.
AK’s discovery of the vertically upward extrusion and inline annealing process followed unsuccessful attempts at extruding PEEK horizontally and vertically downwards. The horizontal attempt, performed with a 24” (61 cm) gap between the die head and the quench bath, resulted in a semi-crystalline tube but with inconsistency in outer diameter (OD) and ovality. Horizontal extrusion resulted in a non-uniform level of crystallinity between the top and the bottom of the tube. The vertically downward attempt resulted in a “snake-like” product with bends and kinks in the tube, due to the PEEK not having enough melt strength to hold the weight of the extrudate.
April 17, 2013: American Kuhne Launches New Line of Modular Micro Extruders
Back in February 2012, US-headquartered extrusion machinery supplier American Kuhne introduced its new Modular Micro Extruder at the MD&M West exhibition in Anaheim, California, USA. American Kuhne ran a Pebax 6333 micro tubing system that included their new 12 mm Modular Micro Extruder with servo drive and pressure control. This extruder is said to provide the versatility to quickly and easily change barrel and screw diameters and feed section geometry configurations—allowing for fast product change overs and thorough bare metal cleanouts.
The new modular micro extruders are available in 12 mm, 16 mm and 19 mm barrel/screw sizes and are suitable for medical device and pharmaceutical applications. Very low output volumes can be achieved down to 125 grams/hr using standard size pellet shapes and granules. Typical resins for micro catheters are processed such as Pebax, nylon, and polyurethane, high temperature polymers such as PEEK and FEP and bioresorbable polymer formulations such as PLA. Complete micro extrusion systems are available for the production of tight tolerance medical tubing, co-extruded tubing, fine wire jacketing, filaments and solid dosage forms.
According to Steve Maxson, vice president of extrusion systems at American Kuhne: “Micro extruders allow for a short residence time in the barrel, which helps to minimise thermal degradation especially compared to traditional size extruders running at very low screw speeds. A shorter residence time protects the molecular weight of the material and ultimately the physical properties of the end product that it is use in. This is especially important for developers of medical devices, dissolving oral dosage forms and drug-eluting devices.”
2011: American Kuhne Announces US Medical Seminar & Open House in May
Medical plastic extrusion equipment manufacturer American Kuhne has announced its Spring Medical Seminar and Open House on May 24-25, 2011.
The event will offer participants valuable technical medical extrusion knowledge and processing tips.
Technical training and discussions will be held on May 24th at the Mystic Marriott Hotel, (located in Groton CT) with presentations by industry experts from American Kuhne (including company president William Kramer), materials handling equipment supplier Conair, process monitoring equipment supplier Zumbach Electronic, catheter and guidewire equipment supplier ASG Medical System, catheter tipping equipment supplier Vante, Northeastern University (NEU) and Guill Tool.
Following the presentations on the 24th will be a complimentary cruise aboard the S.S. Sabino cruise line complete with hors d'oeuvres and beverages. Over 100 years old, the steamboat Sabino was built in Maine in 1908 for passenger service on the Damariscotta River.
During the open house held on May 25th at American Kuhne headquarters (located in Ashaway, RI) the company will be running the following three lines simultaneously:
A 3-lumen TPU taper tube on a 1” (25mm) Modular Gearless extruder with AKcess Level I Touchscreen, Zumbach OD system with taper monitoring, Zumbach 3-channel air pressure controller, Conair MEDVAC vacuum tank, Medline taper puller/cutter, blow-off conveyor, American Kuhne spiral flow crosshead and Dri-Air dryer.
A .141” (3.58mm) OD x .100” (2.54mm) ID tube from a PVC-free, medical grade elastomer resin. Line speeds will be 600 ft/min and higher. We will use an ULTRA series 2.0” (50mm) extruder with AKcess Level II Touchscreen, Guill inline spiral flow die head, Conair Servo driven multi-pass vacuum tank, servo driven nip roller, automatic cut and transfer coiler and a Zumbach ID/OD/WALL system.
The ULTRA R/S 1.5” (38mm) silicone extruder with vertical oven, American Kuhne crosshead, Zumbach OD system and a Conair puller/cutter.
The cost of the seminar is $395 per attendee. Breakfast and lunch for both days will be provided to the attendees and a special rate of $99/night at the Mystic Marriott Hotel and Spa is available. Attendance is limited to 60 people - early registration is recommended to secure a spot.
June 2011: American Kuhne and Teknor Apex Team Up for Extrusion of PVC-Free High Tolerance Medical Tubing
At a recent American Kuhne Open House, American Kuhne and Teknor Apex teamed up to display a PVC- free medical tubing line that ran at speeds up to 830 ft/min while processing Teknor Apex’s Medalist® medical elastomer, the companies announced jointly at MD&M East.
The high speed extrusion line ran a 0.105 in. (2.67mm) OD x 0.020 in. (0.508mm) wall tube up to 830 ft/min (253 m/min.) line speed. At 600 ft/min (183 ft/min) line speed, tight tolerances of +/- 0.0004 in. on the OD and +/- 0.0001 in. on the wall thickness were held. The extrusion system consisted of an American Kuhne ULTRA series 2.0 in. (50 mm) extruder with AKcess Level II Touchscreen System; inline spiral flow die head; Conair multi-pass vacuum tank with servo driven wheel to minimize the rubber band effect and to minimize tension within the process; servo driven nip roller puller; automatic cut and transfer coiler and a Zumbach ID/OD/WALL tube measurement system with closed-loop control of the OD and wall thickness. The compound used in this run was MD-585, an 83 Shore A compound that is part of the Medalist® MD-500 series for tubing applications.
“American Kuhne is a premiere supplier of extrusion systems and has great expertise in the technology for producing medical tubing,” noted Nick Sandland, senior medical marketing manager for the Thermoplastic Elastomer Division of Teknor Apex. “The company’s flawless high-speed demonstration run of our Medalist elastomer adds new confirmation that MD-500 series tubing compounds truly are fully practical alternatives to PVC.”
Recent innovations in radio frequency welding, adhesive bonding, and solvent bonding enable components produced from Medalist elastomers to be used as readily as PVC in the assembly of medical devices, Sandland noted. “Today it’s clear that Medalist MD-500 compounds provide the total package of requirements for successful tubing applications—processability, ease of fabrication, and outstanding end-use performance.” American Kuhne Seminar Focused on Extrusion Technology for Medical Applications
The American Kuhne Spring Medical Seminar and Open House offered participants valuable technical knowledge and processing tips about medical extrusion. The sold-out two-day event attracted over 80 participants.
The key message delivered for Teknor Apex at the event was that the Medalist® MD-500 Series compounds are the first fully practical alternative to PVC for many tubing applications, noted Sandland. “It’s not just that they provide mechanical properties equal to or better than those of the flexible PVC widely used for medical tubing; at least as important, they yield tubing that looks and handles like PVC. This means similar crystal clarity, clamp resilience, resistance to kinking and necking, and an overall PVC-like ‘feel’”.
Sandland also cited some important advantages over PVC: “Medalist elastomers are substantially more flexible. They are less dense, meaning that one can process more feet of tubing per pound of compound. And they exhibit minimal color shift upon heat aging after exposure to gamma irradiation, the most severe type of sterilization.”
A typical compound in the series, Medalist MD-575, actually exhibits 70% less heat-aged color shift than a gamma-stabilized PVC compound of comparable hardness.
“The Medalist material was easy to handle while stringing up the line and also while coiling at the end of the line,” said Steve Maxson, VP Extrusion Systems of American Kuhne. “The material is extremely forgiving, with very stable processing conditions at high extruder output levels, which means that tight tolerance levels can be achieved at very high production line speeds.”