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Evaluating Temperature Influence on Low-Cost Microphone Response for 3D Printing Process Monitoring
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1  São Paulo State University
Academic Editor: Stefano Mariani


The 3D printing process deals with the manufacture of parts by adding layers of material onto a heated printing bed. Electret microphones are widely used, low-cost and precise measuring devices. However, its response is negatively affected by higher temperatures due to the Field Effect Transistor utilized in its construction. The Pencil Lead Break (PLB) method is a standardized artificial acoustic emission source utilized for the evaluation of sensors response. The present work aims to study the electret microphone response for 3D printing monitoring, and to evaluate the efficiency of a proposed housing to reduce the printing bed temperature’s influence on the electret microphone’s response. The microphone housing was 3D-printed utilizing ABS filament, and its geometry was designed with the purpose of separating the sensor from the heated bed and creating an acoustic shell. Then, PLB tests were performed, and the raw signal was collected from housed and non-housed microphones at 5MHz sampling frequency. The sensors were tested under three temperatures of the printer bed: at 25ºC (ambient), at 65ºC (operating temperature), and finally after the temperature of the table was naturally stabilized from 65ºC to 25ºC. The signals were investigated in the time and frequency domain. The results show that the housing impacts the microphone’s response positively when operating at 25ºC, where the signals presented higher amplitudes in both domains. However, the response obtained by the housed sensor was considerably attenuated at 65ºC. Furthermore, the signals collected at 25ºC after exposing the housed microphone to heat demonstrate a “greenhouse effect”, keeping the sensor at higher temperatures for an extended period. It can be concluded that the proposed housing did not succeed in reducing the temperature effects in the sensor’s response. However, these effects were shown to be significant and the need for an alternative method to attenuate them is reinforced.

Keywords: 3D-printing; Process Monitoring; Signal Processing; Sensor's Response Evaluation; Temperature; Pencil Lead Break Method