TECHNOLOGY | MACHINERY DIES
Cross-heads coat single- and multi- layer pipes in diverse applications
Austria-based Conextru has developed a range of cross-heads that can coat both steel and plastic pipes. Pipe coating offers flexible produc- tion and can be integrated into existing extrusion lines. The coating structure can be mono- or multi-layer. Monolayer coating is mostly as a final protection layer and applications are diverse. Examples include a PP protection layer for water pressure pipes, or a PE-RT layer for an RTP pipe used in oil and gas applications. “The range in diameters goes from very small up to 1200 mm,” said Josef Dobrowsky, managing director of Conextru.
Multi-layer structures are also possible, and can be applied to steel MEDICAL Teaming up for polycarbonate pipettes
Conair, Davis-Standard and Zumbach Electronics will demonstrate extruded polycarbonate pipettes at the forthcoming MD&M West/Plastec West 2023 show in Anaheim, USA. The pipettes are made
by extruding medical- grade, 0.25in polycarbon- ate tube, which is then cut into 5in pipettes that need no secondary cleaning or finishing operations. Several Conair products are used on the line. The polycarbonate will
be pre-conditioned using a Conair dX25 Carousel Plus desiccant dryer. It regulates critical drying setpoints and resin moisture and automatically
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regulates material move- ment through to the extruder. Polycarbonate moving from the hopper to the extruder also passes through Conair’s Moisture Minder, an in-line device that reads the moisture content of moving resin. The material is pro- cessed in a Davis-Standard 1.25-inch HPE Horizontal Extruder, which has the torque capacity to handle high-viscosity resins. It is available in sizes from 0.75in (20 mm) to 1.75in (45 mm). From here, the melt passes through sizing inserts as it enters a water- filled, non-contact calibra- tion head mounted at the
PIPE & PROFILE EXTRUSION | January/February 2023
touchscreen HMI. The vacuum chamber in the MedVac sizing tank creates a differential in
front end of a Conair MedLine MedVac 235 vacuum sizing tank – which supports cleanroom applications and is equipped with automatic vacuum control and
air pressure that exerts slight outward pressure in the extruded tube, stabilis- ing its dimensions. Here, ultrasonic wall-thickness gauges from Zumbach measure the OD and wall thickness of the tube, first as hot extrudate enters the tank and also later as it cools. This is used to calculate
the ID of the tube – the dimension most critical for medical fluid delivery. �
www.conairgroup.com �
www.davis-standard.com �
www.zumbach.de
www.pipeandprofile.com
or plastic pipe. Typical polymers for such applications include polyamide, PET, EVOH and PPS. A cross-head system typically consists of a helical or radial spiral distributor. Conextru offers a library of geometries for this melt distribution systems and – depending on material and output – the most suitable geom- etry is applied. There is no standard product range
as each head is tailored for a project. Making a new one typically takes between three and five months. The largest head produced so far is a monolayer head up to 1200 mm for coating steel-reinforced RTP pipes. The smallest so far is for applying a two-layer coating to a 16 mm pipe. �
www.conextru.eu
IMAGE: CONAIR
IMAGE: CONEXTRU
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