Modelling and experimental validation of ultrasonic embossing process

Date

2025-9

Author

Mahmood, Tawsif

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Ultrasonic embossing is a promising microfabrication technique to replicate fine features on polymer substrates with reduced cycle time and energy consumption. This study presents a finite element modelling and experimental investigation of the ultrasonic embossing process. A comprehensive multiphysics finite element model was developed in Abaqus CAE to simulate the coupled effects of vibration, pressure, heat generation, and polymer flow during embossing of polymethyl methacrylate (PMMA) substrates. Replication of 1000 µm wide channels in PMMA was modelled under a static pressure of 3 bar and a vibrating horn frequency of 30 kHz. The model incorporated temperature-dependent material properties and realistic process boundary conditions to predict feature replication accuracy while capturing the coupled thermo-mechanical effects of the process. The results were compared to experimental results via image processing of channel cross sections and thermal imaging. A cross-correlation value of 0.75 between the profile derivatives indicates good agreement between the channel profiles, although some mismatch remains due to uncertainties in mold dimensions. The final temperature at the substrate-mold interface reached 201 °C in experiments and 213 °C in the model, giving a temperature difference of 12 °C. This difference arises from the thermal camera’s acquisition limits, uncertainties in PMMA’s thermal properties, interfacial friction, simplified boundary conditions, and emissivity variations. The accuracy of the model was also verified by comparing the process affected zone (PAZ) from the existing literature. Cross-sectional and thermal images showed strong agreement with simulation predictions, confirming the model’s capability to capture the thermo- mechanical behavior of the polymer during embossing.

Subject Keywords

Ultrasonic Embossing, Thermo-mechanical Modelling, Microchannel, Thermoplastics

URI

https://hdl.handle.net/11511/115650

Collections

Graduate School of Natural and Applied Sciences, Thesis