QMT Features: April 2013
Metrology insight
Nikon Metrology aims to provide better and faster insights into product and processes through innovation as Filip Geuens, chief technology officer, explains.  By Brendan Coyne, QMT.

How has Nikon Metrology evolved since its acquisition by Nikon in 2009?  Filip Geuens, chief technology officer, CTO, for Nikon Metrology says the company has become stronger and more solid as a result of blending the innovative and dynamic atmosphere  of the metrology company with solid Nikon structures and through embracing a long term vision philosophy.

Synergies include the bundling of engineering capacities from Japan and Europe with best practices developed from Nikon standards. This delivers a significant technological advantage as Nikon is a major technology company, with extensive research and engineering capabilities.  These include Nikon’s Core Technology Centre and, of course,   Nikon’s leading edge optical technology.

“Since 2009, Nikon Metrology has experienced  a more than doubling of organic sales growth  (by a factor of  2.5),  outpacing market growth i.e. taking market share. The product line that is performing best is that of X-Ray Computed Tomography (CT).” says Filip Geuens.   “Overall employment has expanded from 420 people to about 550”.  

One reason why the company is outperforming the market is that it provides value for the customer: being part of a large and stable Nikon organization, investments by customers in Nikon Metrology products are  seen as future-proof. With global supply chains and multi-national/multi-plant manufacturing, customers, large or small,  have support from a worldwide organisation.

Another key driver for success is the introduction of  innovative products through continually pushing at the  boundaries of today’s technology. A good example, and  a first fruit of the cooperation with Nikon Japan, is  the Digital LC15Dx CMM laser scanner, which captures complex surfaces and feature geometry in a single scan. Thanks to solid state laser scanner technology, an innovative calibration method and high quality Nikon lens, the LC15Dx achieves a probing  accuracy of 2.5µm and a multi-stylus test accuracy of 6µm in tests comparable to EN/10360-2 and -5.

Thermal stabilization also enables the system to start measuring immediately after powering up the scanner. The LC15Dx also supports a greater range and mix of surface materials, finishes, colours and transitions. “Due to the high accuracy of the scanner, we are more and more able to measure surface quality, defects such as scratches or small surface damage but not roughness,” says  Filip Geuens.  Nikon Metrology’s third-generation Enhanced Scanner Performance (ESP3) technology maintains accuracy, speed and data quality by intelligently adapting the laser settings for each measured point in real-time. Also an advanced software filter neutralizes unwanted reflections while changes in ambient light are absorbed by a high-grade daylight filter. The LC15Dx has the accuracy, resolution and speed to successfully tackle the more demanding applications such as turbine blade metrology.  Other innovative products coming from Nikon Metrology include x-ray CT systems, which combine dimensional metrology and CT technology, and in microscopy, the ShuttlePix portable digital microscope.  

What are the market trends in metrology? “We expect that 50% of our new CMMs will be equipped with both touch probing and non-contact   scanners. This is because with increasing complexity of parts, you cannot generate enough information in all cases with just one type of probing technology, ” says Filip Geuens. ”Its not just increasing complexity of components but also that parts have more new designs and  shorter life cycles.  So metrology rooms have to become more flexible, just like production lines - that’s why they need  a more extended toolbox.” 

Filip emphasizes that its not just speed and flexibility that are drivers, “Users are primarily looking for better insights  into their products and processes. They want to understand their processes and related problems in an efficient way. The focus is on productivity - with faster measurement and  more data.” For example, Ford Otosan, Turkey’s automotive industry leader, uses a Nikon Metrology XC65D laser scanner for the inspection of small commercial vehicles. As an early adopter, Ford Otosan saw laser scanning technology evolve from smaller niche applications to the full vehicle body inspection of its popular Transit Connect model. Detailed Cross

Scanner benchmark tests confirmed similar data quality compared to tactile inspection, and revealed 65% higher throughput. Tactile inspection on a single vehicle body lasted 36 minutes, whereas laser scanning completed the same job in less than 13 minutes.

In terms of data quality, Ford Otosan state there was hardly any difference between laser scanning and touch sensor measurement. Detailed analysis of inspection data revealed that overall laser scanning results were slightly better. Although both technologies meet the 20-50 micron precision level required for sheet metal, the multitude of measuring points captured by laser scanners makes a difference. This aspect is critical in digitizing freeform surfaces completely and extracting accurate positions of features, edges and surface shapes is imperative to verify the process quality of mating parts and judge vehicle body assembly accuracy. Non-contact vehicle body measurement speeds up every step in the process, and delivers more profound insight to take better-informed manufacturing decisions  

“There is a move towards using optical and CT measurement  to get larger data sets on a component, to visualise the entire part, especially to understand what is wrong in the manufacturing process,” says Filip Geuens. “Just getting a measurement report with deviations does not always allow us to see where the deviations are coming from. A colour map derived from a scanner or x-ray CT system gives much more content and allows us to make the link between the deviations and the customer’s production process.”  So, for example, in process control, where laser scanning delivers fast measurement of critical points  during serial/sample inspection, the visualisation of deviation trends will initiate full 3D troubleshooting.

Easy-to-interpret  measurement results of the scanning data allows production process issues  to be clearly identified. Colour maps of measured results   provide part-to-CAD comparisons to facilitate interpretation. Further investigation and analysis is possible using fly-outs, sections and a library of geometric dimensioning and tolerancing (GD&T). Unambiguous measurement analysis of 3D and feature inspection can be communicated, either in pre-production or for troubleshooting. This approach offers the capability to discover and tackle issues in a much faster way.
CT metrology
New production technologies require new inspection technologies. For example, laser sintering, and additive manufacturing, produce small and highly complex components that can't be inspected using touch probes or optical sensors. These components often suffer from voids or internal deficiencies. X-ray computed tomgraphy (CT) metrology systems offer a way to inspect in and outside dimensions, as well as provide insights in internal structures, materials, mechanisms.

 “We are trying to bring  x-ray CT technology into the industrial metrology marketplace. We are not just looking at NDT technology for inspecting material defects but also using it for dimensional control,” explains Filip Geuens.  “At present, there are two separate markets. Customers are not yet combining  dimensional metrology with material integrity  verification. We believe this will be an evolution in the market., especially when we have new manufacturing technologies. We see a shift taking place from traditional CMMs to CT systems as this technology can generate much more information on  a part. You get a complete digital model of the part, inside and outside.”

In response to this perceived demand, Nikon launched the Metrology CT last year. Metrology CT is the fusion of metrology and X-ray Computed Tomography.  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.    

Nikon’s vision is to perform dimensional quality control and material integrity control in one NDT measurement. It has developed a new “absolute accuracy” metrology computed tomography system,  the MCT225, which  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 visualization of the sample volume provides valuable insights into part deformations and internal structural integrity. 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.

“Using Metrology CT technology, plastic injection-mold and metal die-cast manufacturers can significantly reduce correction cycles during tool development and production start-up, accelerating time to market for new product,” explains Jos Jans executive VP marketing manager for Nikon Metrology. “To inspect relatively small but complex components in the plastics injection molding industry, very often they must be sliced. Then, using a vision system or CMM, you inspect the slice.

However,  slicing also destroys the component. Several iterations have to be done to set up the right process parameters.  With Metrology CT, the measurement time is fast and provides  full inspection data at one time - eliminating the need for further iteration.  All shrinkage, deformation and dimensional errors are clearly identified in easy to understand inspection reports making it easier to define corrective actions.”
What about future developments? “We believe we can bring 3D metrology to more markets than just industrial, such as high resolution x-ray CT into the medical sector.” says Filip Geuens. “In the industrial market, the sector is experimenting  with in-line metrology. But there is no consensus, no clear direction about which way to go. Everybody wants to bring metrology closer to the point of manufacture but it could go in different ways.  Which ever way it goes, we believe we have the technology and knowhow to lead metrology developments in the future.”l

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