Extraction Unit Allows Safe Molding of Teflon

Technical parts made from Teflon are often machined because the polymer begins to decompose into hazardous fluorocarbon gases above 662°F.

German electronics equipment producer Rohde & Schwarz, however, is significantly reducing the per-part cost of Teflon for a micro application with a specially developed molding cell. The part is a Teflon spacer used in high-frequency components.

High-precision Teflon spacers are used in high-frequency components. (Photo: Wittmann Battenfeld)

Micro injection molding machines from Wittmann Battenfeld are enclosed and equipped with an extraction unit with a thermo microbalance combined with an infrared spectrometer.

The thermo microbalance determines changes in mass while gases released from samples are measured by a Fourier-Transform infrared spectrometer, which covers spectral range from 500 cm-1 up to 6.000 cm-1. Integrated flow controllers ensure precisely regulated flow quantities for two flushing gases and one shielding gas.

“With this method, Rohde & Schwarz was able to prove beyond doubt that processing of the Teflon used does not involve any health or safety hazard for the workers,” stated a press release issued by Wittmann Battenfeld.

To achieve very tight tolerance requirements, the two micro machines are located in an air-conditioned room where both temperature and humidity are kept constant. The molds and the material are also stored in the room. MicroPower machines (5 to 15 metric tons of clamping force) use a two-step screw-and-plunger injection unit with shot volumes ranging from 0.05 to 4 cm³.

While the machined parts had to be deburred, no secondary finishing of the injection molded parts is required.

The Rohde & Schwarz plant is in Teisnach, Germany. The company, which is highly integrated, makes its own molds and its own EDM milling equipment to achieve tolerances of ±3 μm. Typical micro parts made by Rohde & Schwarz in Teisnach are power plugs with a tolerance margin around ±12 μm between the internal and external conductors.

Micro injection molding machines at Rohde & Schwarz are located in an air-conditioned room. (Photo: Wittmann Battenfeld)

About Doug Smock

Former Chief Editor at Plastics World and Senior Technical Editor Design News
Automation/Robotics, Automation/Robots, Electronics, Europe, Micro Molding , ,

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