Nikon Metrology combines CMM and CT experience in the MCT225 metrology system
1 min read
Nikon Metrology has combined its Co-Ordinate Measuring Machine (CMM) metrology with its X-ray Computed Tomography (CT) experience to develop an 'absolute accuracy' metrology CT system, the MCT225. This provides metrology CT for a wide range of sample sizes and material densities with 9+ L/50 µm accuracy, in accordance with the VDI/VDE 2630 guideline. All internal and external geometry is measured in a single non-destructive process. A full 3D visualisation of the sample volume additionally provides insights into part deformations and internal structural integrity.
Metrology CT has long been used for industrial applications. With X-ray CT a number of 2D X-ray images are taken at different angles around the sample. All of the external and internal geometry is captured as the X-rays pass through the sample. CT software constructs a 3D model of the sample using these 2D images. Dimensional characteristics such as size, position and form can be measured directly using the model as well as full part-to-CAD comparison, section reporting and GD&T analysis.
MCT225 is pre-calibrated using accuracy standards traceable to the UK's national measurement institute (NPL) and verified using VDI/VDE 2630 guidelines for Computed Tomography in Dimensional Measurement.
'Absolute accuracy' guarantees measurement accuracy without time consuming comparative scans or reference measurements; samples are simply placed on a rotary table inside the enclosure and measured.
A key component of the MCT225 system is the in-house developed Nikon Metrology 225 kV micro-focus X-ray source. It produces incredibly sharp images with low noise levels, enabling magnification levels up to 150X with 2 µm feature detection.
High precision linear guideways equipped with high resolution optical encoders are error corrected using the laser interferometer mapping techniques employed for CMMs. For optimal accuracy and long term stability, Finite Element Analysis (FEA) was used during the design phase to optimise the stiffness of the manipulator
To minimise thermal effects the interior of the MCT225 enclosure is temperature controlled, effectively creating a conditioned measurement room stable to 20°C ±1°C.
MCT255 can reduced leads times and inspection cycles for manufacturers. The powerful X-ray source and large capacity manipulator combine with high magnification and detailed feature detection to create a solution suited to a wide variety of applications.
Plastic injection-mould and metal die-cast manufacturers can significantly reduce correction cycles during tool development and production start-up. All shrinkage, deformation and dimensional errors are clearly identified in easy to understand inspection reports making it easier to define corrective actions.
Emerging production techniques like additive manufacturing now make it possible to produce small and highly complex components that can't be inspected using touch probes or optical sensors. Here too MCT225 makes it possible to measure and analyse these components in a single non-destructive operation.
