Stefania Gasparin

Dimensional measurement of micro-moulded parts by computed tomography

Computed tomography (CT) is progressively assuming an important role in metrology applications and great efforts are being made in order to turn it into a reliable and standardized measuring technology. CT is typically used for non-destructive tests, but it is currently becoming very popular for dimensional metrology applications due to its strategic advantages such as the capability of performing measurements on both the components surface and volume, allowing inspection possibilities to otherwise non-accessible internal features. This paper focuses on the dimensional verification of two micro-injection moulded components, selected from actual industrial productions, using CT metrological tools. For this purpose, several parts have been measured with two different CT machines, and the results have been compared with the measurements obtained by other measuring systems. The experimental work carried out and the analysis of the results provide valuable conclusions about the advantages and drawbacks of using CT metrology in comparison with other measuring systems when these techniques are employed for the quality control of micro-moulded parts.

Challenges in high accuracy surface replication for micro optics and micro fluidics manufacture

Patterning the surface of polymer components with microstructured geometries is employed in optical and microfluidic applications. Mass fabrication of polymer micro structured products is enabled by replication technologies such as injection moulding. Micro structured tools are also produced by replication technologies such as nickel electroplating. All replication steps are enabled by a high precision master and high reproduction fidelity to ensure that the functionalities associated with the design are transferred to the final component. Engineered surface micro structures can be either distributed, e.g., to create an optical pattern, or discretised, e.g., as micro channels for fluids manipulation. Key aspects of two process chains based on replication technologies for both types of micro structures are investigated: lateral replication fidelity, dimensional control at micro scale, edge definition. The parts investigated are a micro retroreflector and a micro fluidic system, typical applications of injection moulded parts with micro structured functional surfaces.

Dimensional metrology for process and part quality control in micro manufacturing

Micro manufacturing has gained interest over the last decade as the demand for micro mechanical components has increased. The need for dimensional metrology at micro scale is evident both in terms of quality assurance of components and products and in terms of process control. As critical dimensions are scaled down and geometrical complexity of objects is increased, the available measurement technologies appear not sufficient. New solutions for measuring principles and instrumentation, tolerancing rules and procedures as well as traceability and calibration are necessary if micro manufacturing is to develop into industrial manufacturing solutions. In this paper the application of dimensional precision metrology to both component and process quality control will be demonstrated. The parts investigated are micro injection moulded polymer parts, typical for the field of micro manufacturing.

Correction of systematic behaviour in topographical surface analysis

(14/12/2018) Correction of systematic behaviour in topographical surface analysis Four specimens in the sub-micrometre range and with different polishing were topographically investigated in fiveareas over their respective surfaces. Uncertainties were evaluated with and without correction for systematicbehaviour and successively analysed by a design of experiment (DOE). Results showed that the correction forsystematic behaviour allowed for a lower value of the estimated uncertainty when the correction was adequate tocompletely recognise the systematic effects. If not, the correction can produce an overestimation of the uncertainty.