Browsing by Author "Sandwell, Allen"

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    Open Access
    Development of an Optical System for High Precision Multi-Axis Force Measurements
    (2015-10-19) Sandwell, Allen; Park, Simon
    Accurate and precise force measurements are critical in machining operations for maximizing production, detecting tool failure, and monitoring. Currently, the most accurate force sensors are piezoelectric sensors. The accuracy of these sensors is very high, yet they are expensive, are limited in their measurement bandwidth and are only suited for dynamic measurements. To overcome the challenges of existing sensors an alternative incorporates optical components to measure very small displacements. The sensor uses photo detector technologies which can measure positional changes from a laser on the order of nanometres. To improve sensitivity a mechanical amplification system based on levers is introduced, along with algorithms to extract the effects of multiple sources and a single detector. To extract more accurate information, an analysis of the photodiode and laser beam characteristics is performed. For implementation, a prototype sensor is fabricated. The sensor is benchmarked against a commercial dynamometer to characterize performance.
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    Open Access
    Development of Nanocomposite Sensors for Smart Work holding System
    (2022-01) Sandwell, Allen; Park, Simon; Hugo, Ron; Li, Simon; Xue, Deyi
    The advent of Industry 4.0 necessitates developments of new sensor technologies. One of the emerging techniques of fabricating these new types of electronics and sensors is by depositing conductive inks and additional electrically active materials to serve as sensor layers onto flexible polymeric substrates. This study presents copper nanoparticle-based inks. The new formulation is developed that provides both oxidation resistance as well as improved flexibility with suitable rheological properties for deposition using traditional screen-printing practices. To create a conductive matrix from the deposited ink, a sintering step is needed. Intense pulsed light (IPL) using a xenon flash lamp is used to sinter the ink. As the IPL sintering process is applied to the surface of the ink, the sintering process and resulting materials are analysed. The addition of polymeric nanocomposite-based films has significant benefits when used as the sensing layer. In this study we developed a sensing material comprised of (poly)vinylidene fluoride as a piezoelectric polymer matrix, along with carbon nanotubes to create an electrically conductive network. Exhibiting both piezoelectric and piezoresistive properties, the developed sensors are capable of measurement in a wide frequency band. The performance of these nanocomposite sensors was assessed as they are subject to an applied strain under both static and dynamic conditions. As an application for the printed sensors, we investigate their suitability as imbedded sensor systems for smart workholding. We present the design of a smart chuck (the SmartJaw) that can measure the gripping forces on a workpiece during machining operations on a lathe. Continuous monitoring of the jaw clamping forces provides the required feedback to minimize the likelihood of adverse events occurring. Analytical models are developed and presented that reconstruct the cutting forces based on the input jaw gripping forces and other parameters such as spindle speed, workpiece geometry and tool location. The accuracy of the models is examined. The SmartJaw is fabricated using the developed nanocomposite sensors and conductive inks, and the performance is compared with the commercial strain gauge system. Both accurate and precise measurements of forces are critical in machining operations for maximizing production, detecting tool failure and process monitoring.