Customized solutions for innovative technologies in aerospace

Automated measurements along with repeatable and traceable 3D measurement data convinced Metallicadour, a French technology transfer center specialized in aerospace applications, to go for Alicona. For developing innovative tool and automated machining solutions, the research team verifies geometric dimensions and surface finish on tools and components using optical 3D metrology.

New applications in the aerospace industry and the rapid pace of technological change lead to an increasing demand in tooling. With Alicona’s optical measurement technology, the expert team at Metallicadour found the ideal solution for measuring complex geometries and hard-to-machine materials, such as titanium, composites and heat-resistant alloys.

Metallicadour is a resource and technology transfer center devoted to the metal industry and fields of machining, assembly and process automation. The center is supported by major local aircraft manufacturers, among them Safran, Daher and Dassault. Metallicadour enables component manufacturers to test and automate machining processes and demonstrate the interest in new cutting technologies, such as very high pressure lubrication and cryogenic turning.

Testing of new machining tools and technologies for aircraft construction

Verification of form and roughness has a major influence on the service life of a tool and can significantly reduce wear and chatter for an improved surface finish of components. “Cutting tools for machining aerospace components have to meet the highest precision requirements for high-speed machining. Therefore, geometry and edge conditions need to be addressed”, Pierre Courbun, Development Engineer at Metallicadour explains. “With Alicona we found what we were looking for: A measurement solution that provides us with precise, repeatable measurements as well as simplicity and flexibility in use.”

As the measured parts and requirements vary, Metallicadour highly benefits from the “all-in-one-solution” measurement solution by Alicona. It is applied for all kinds of measurement tasks, including form and roughness measurement of mills, inserts and drills. Pierre Courbun: “Our components often show steep flanks, deep lengths and light refection. With Alicona, we measure small surface connection radii and the geometry of very complex surfaces. We also verify roughness on components with very smooth surfaces or parts that are way too small to be measured tactile.”

New insights into cutting processes and wear behavior of tools

Based on the technology of Focus-Variation, Alicona allows for profile (Ra, Rq, Rz) and area-based measurements (Sa, Sq, Sdr). With up to 500 million measurement points it provides robustness of the measurement data. Accuracy of roughness measurements can be verified with a roughness standard that is traceable back to the PTB (National Metrology Institute of Germany).

The 3D measurements are compared against CAD data or reference geometries for verification of accuracy. This helped Courbun and his partners on understanding the cutting phenomenon and related indicators: “With our measurements we compare different tools and materials to investigate wear behaviour. We study the correlation between cutting forces, wear and performance of the tool, respectively the roughness generated by the tool over its full life cycle. Moreover, we also investigate the links to the matter of surface material as well as the change of mechanical surface tension”.
Alicona is also used in the development of new machining solutions. Courbun continues: “We are working on an automated manufacturing solution, where the workpiece is processed by a milling robot. Following each process step, the component is automatically measured for verification of dimensions and possible deviations from the target geometry. This is implemented by another robot that is equipped with Alicona’s optical sensor. Based on the high-resolution measuring data, the machine automatically modifies the process parameters for further manufacturing.”

Robot-based solutions for automated defect detection of aircraft components

In joint research and development projects, Metallicadour and Alicona also implemented automated defect measurement on rotor blades as well as new collaborative robot solutions (cobots) for quality control of landing gears, turbine discs and other large components. Defects on rotor blades as well as engine and other aircraft components are safety-critical when they cause stress points which in turn create a crack. When the local stress concentration becomes too high or the crack reaches a critical size, the remaining material cannot support the applied loads. This may result in a fracture or sudden rupture. The defects can be caused by machining errors, corrosion or external influence, i.e. the impact of stones and debris. “Before, components could only be evaluated throughout human visual check. With Alicona local surface defects are automatically measured, so that shape and size of defects can be quantified in MRO and process development”, Pierre Courbun points out. If the defect is outside a defined tolerance it must be removed by dressing until it is acceptable or, if not possible, the workpiece has to be scrapped and replaced.

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