Multi-sensor metrology for microparts in innovative industrial products

Micro-parts with complex geometries are increasingly used in the automotive, medical, and telecommunications industries. Products, such as micro-gears, fuel injection systems, or drug delivery mechanisms all rely on accurate and reliable 3D measurements. Micro-coordinate measurement machines (CMMs) are used to measure components with small features using tactile probes or optical sensors. X-ray computed tomography (CT) systems are beginning to provide dimensional measurements of the complete geometry including inaccessible features, but these often lack traceability. Combining and analysing data from different sensors, such as CT, optical devices, and tactile probes, also presents a challenge in terms of reconciling coordinate systems and producing consistent data sets.

The EMRP project Multi-sensor metrology for microparts in innovative industrial products developed a consistent and reliable 3D measurement framework using data from multi-sensor inputs.

The project:

• Demonstrated that diamond-coated CMM probes are more durable and accurate for industrial tactile measurements of very fine structures, in comparison to conventional ruby probes.
• Developed and validated a series of reference materials with complex shapes, enabling increased accuracy for optical and CT measurements in industry.
• Evaluated task-specific multi-sensor measurement uncertainties using three industrial reference standards, and developed and improved virtual models to simulate micro-coordinate measurement uncertainties.
• Provided insights on the effects of linking the different coordinate systems used for making measurements of the same part (tactile, optical, and CT), and determined improved approaches to reduce measurement uncertainties.
• Developed a simulation method to identify systematic errors in CT measurements of micro-parts, resulting in a 50% increase in dimensional accuracy.

Essential micro-parts, whether micro-gears in insulin pumps or lens implants used to restore sight after cataract surgery, must meet micrometre tolerances. This project has improved the accuracy of industrial measurements by improving CMM probes, combining different sensors and measurement techniques, and providing better traceability through use of reference standards. European manufacturers of intricate micro-parts can now benefit from greater accuracy in CMM probe calibrations, which will contribute to improved quality and competitiveness in many industrial sectors. Overall, the project has delivered greater measurement reliability to support increased penetration of the global precision engineering market by European micro-part and microsystem manufacturers. A follow on EMPIR project Advanced Computed Tomography for dimensional and surface measurements in industry (AdvanCT) will build on the EMRP project developments to promote SI traceability and greater industrial uptake of CT measurements for complete geometry determination including inaccessible features.