Foaming of fluoropolymers

Foaming of fluoropolymers

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For a number of new applications such as mobile phones, LED displays, medical probes micro-sized wires with special insulation are required. To meet size requirements and electrical performance this insulation needs to be foamed. For mechanical, thermal and electrical purposes mainly fluoropolymers such as FEP or PFA are used in this area.
This paper describes the state of the art process equipment and the required auxiliaries and process conditions for manufacturing highly expanded fluorpolymer-insulated LAN-, Mini- and Micro-Coaxial cable with special consideration of equipment design, tool design and material properties.
A whole new range of equipment needed to be developed coping with the challenges of micro-sized wires down to 25 microns diameter. Tension control in the insulation line has to cope with tensions as low as 4 grams with tolerances of +/- 2 grams otherwise wire elongation will lead to breaks or increased resistance. Foaming technology for wall thicknesses down to 80 micron requires extruders with output of 0,2 kg/hr and new insulation materials either ready mixed with nucleating agents and/or specifically blended materials, utilizing the advantages of the individual resins allowing cell sizes smaller than 25 microns diameter and sufficient melt strength to achieve economical production speeds.
Crossheads for this product range and material throughput need to be miniature in size, yet allowing easy threading and stable processing of the material in either single layer, double layer or triple layer designs. Further challenges to master are the cooling of the product at the right place and winding. Also diameter, lump-, capacitance- and eccentricity gauges as well as spark testers are required to work in this range with sufficient accuracy.
All this led to a number of new designed machines combined to a line configuration mastering the challenges to achieve the targets. This paper describes state of the art process equipment and the required auxiliaries and process conditions for manufacturing highly expanded fluoropolymer insulated Micro-Coax-Cable with special consideration of equipment design, tool design and material properties.

SKU: P05477 Category:

Description

For a number of new applications such as mobile phones, LED displays, medical probes micro-sized wires with special insulation are required. To meet size requirements and electrical performance this insulation needs to be foamed. For mechanical, thermal and electrical purposes mainly fluoropolymers such as FEP or PFA are used in this area.
This paper describes the state of the art process equipment and the required auxiliaries and process conditions for manufacturing highly expanded fluorpolymer-insulated LAN-, Mini- and Micro-Coaxial cable with special consideration of equipment design, tool design and material properties.
A whole new range of equipment needed to be developed coping with the challenges of micro-sized wires down to 25 microns diameter. Tension control in the insulation line has to cope with tensions as low as 4 grams with tolerances of +/- 2 grams otherwise wire elongation will lead to breaks or increased resistance. Foaming technology for wall thicknesses down to 80 micron requires extruders with output of 0,2 kg/hr and new insulation materials either ready mixed with nucleating agents and/or specifically blended materials, utilizing the advantages of the individual resins allowing cell sizes smaller than 25 microns diameter and sufficient melt strength to achieve economical production speeds.
Crossheads for this product range and material throughput need to be miniature in size, yet allowing easy threading and stable processing of the material in either single layer, double layer or triple layer designs. Further challenges to master are the cooling of the product at the right place and winding. Also diameter, lump-, capacitance- and eccentricity gauges as well as spark testers are required to work in this range with sufficient accuracy.
All this led to a number of new designed machines combined to a line configuration mastering the challenges to achieve the targets. This paper describes state of the art process equipment and the required auxiliaries and process conditions for manufacturing highly expanded fluoropolymer insulated Micro-Coax-Cable with special consideration of equipment design, tool design and material properties.

Additional information

Author(s)

Gerhard Hofer, Rosendahl Maschinen GmbH, Austria
Publication/Event/Pages

Paper presented at WAI's International Technical Conference in Düsseldorf, Germany, Nov., 2011.
Year

2011

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