Measurement of temperature and pressure distribution during ultrasonic processes by sensor foils from polyvinylidene fluoride

Kosloh, Julia; Sackmann, Johannes; Krabbe, S.; Schomburg, Werner Karl

doi:10.1007/s00542-018-3832-3

Cited by 3 publications

(2 citation statements)

References 24 publications

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“…Besides this, larger sonotrodes tend to show an inhomogeneous distribution of the vibration amplitude over their area (Kosloh et al 2018). As a consequence, at a certain position under the sonotrode the micro structures may not yet be embossed completely, and at the same time, at another position the polymer is already decomposed and no longer suitable to form a proper micro structure.…”

Section: Introductionmentioning

confidence: 99%

Friction embossing

Zou

Schomburg

2020

Microsyst Technol

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A new fabrication process for micro structures from thermoplastic polymers is presented. Two layers of thermoplastic polymer are placed onto a tool with micro structures. By a friction welding machine, the polymer surfaces are rubbed against each other generating friction heat and melting the polymer. The polymer adapts to the surface shape of the micro structures on the tool. Then, the movement of the machine stops and the polymer cools down and hardens in the shape of the micro structures. The entire process is finished within a few seconds and the required investment costs are in the range of some 10,000 € to approximately 200,000 €. Compared to ultrasonic hot embossing, samples with larger overall dimensions can be fabricated and the heat distribution has been proven to be more homogeneous.

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Section: Introductionmentioning

confidence: 99%

Friction embossing

Zou

Schomburg

2020

Microsyst Technol

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“…These difficulties also occur when pressure and temperature distribution shall be measured in the process of ultrasonic welding. In recent papers, there is described how temperature and pressure during ultrasonic welding were measured employing thin film thermocouples, and both piezoelectric and pyroelectric sensor foils from polyvinylidene fluoride (PVDF) [23][24][25][26][27][28]. This paper introduces the simultaneous measurement of shear stress and temperature rise generated in PVDF foils by linear and circular friction welding.…”

Section: Introductionmentioning

confidence: 99%

PVDF Sensor Foils Employed to Measure Shear Stress and Temperature of Friction Welding

Zou

Schomburg

2020

Sensors

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Friction welding is a popular process for joining metal and polymer work pieces by rubbing them against each other. This way, friction heat is generated in a zone of the faying surfaces, thinner than 1 mm. After cooling down, the heated surfaces establish a tight and strong bond. To improve this joining process, a method is desirable allowing measuring generated temperature and shear stress in the zone between the joining work pieces. Unfortunately, this is a very difficult task because the welding zone cannot be accessed with a sensor without significantly altering the process and thereby the desired measurement results. This paper describes how shear stress and temperature change generated by rubbing polymer pieces in a friction welding machine have been measured between the faying surfaces by employing sensor foils from the piezoelectric and pyroelectric polymer polyvinylidene fluoride (PVDF). This way, heating and cooling rates, pressure rise of the pneumatic system, frequency rise of the starting machine, the duration of starting and stopping, the damping of the vibrations after the drive was stopped, and the stress generated by the pullback of the machine head have been measured. A careful characterization of the sensor was necessary to enable distinguishing the measured voltage due to straining, shearing and temperature change.

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