Innovative grinding process for turbine blades unveiled at International Paris Air show

According to Haas Schleifmaschinen, materials used in turbine technology are becoming harder and tougher to match the ever increasing temperatures in jet engine turbines that support improved efficiency and save fuel are employed. The focus is, therefore, shifting to the grinding process, as other cutting processes are no longer much of an option, according to the company. With its new process, connection areas and attachment geometries at both ends of the turbine blade segments are produced. An innovative tensioning system, combined with an intelligent processing strategy based on Haas Schleifmaschinen's new Horizon grinding software, significantly simplify the process and increase cost efficiency. The solution also guarantees compliance with the high standards of precision and safety required in the aerospace industry. Intelligent tensioning system In the previous process, components were encased in a bismuth block to ensure stable tensioning. Once the grinding process was completed, the bismuth had to be melted to be removed. Limited axes available on simpler grinding machines were compensated for via numerous grinding tools. The new application uses two half shells as a tensioning tool, with these produced specially for the components, practically like a mould. The component is placed in the bottom shell and the top shell fixes it. The two ends of the turbine segment to be processed remain exposed. This 'sandwich' can be securely and stably tensioned, as well as handled and turned by a robot, so that both sides can be processed. The time-consuming and expensive bismuth mount is no longer required and the component material is no longer exposed to thermal effects caused by the melting process. The Mutligrind universal grinding machines with five axes also make it possible to implement a processing strategy that uses considerably fewer grinding discs, which also beneficially impacts tool changing times. Revolutionary software concept Multigrind-Horizon machine software is a revolutionary new concept for grinding machines. Starting right from the user interface, the software differentiates itself from typical industrial standards. A chess-board-style navigation interface provides users with an overview of all grinding process key parameters. Navigation is intuitive and inputs are standardised to make the user-experience similar to that of operating a Smartphone. This is thanks to the modern software architecture, which always keeps the screen content separate from the calculations. The operator no longer sees most of the calculation processes, which happen in the background, and only needs to enter the relevant data. Programming is undertaken with respect to the part CAD model, which makes a CAM system unnecessary. The operator can see the blade segment model and both half shell tensioning tools on the screen. Even the grinding surfaces are visualised as lines. If users click on one of these lines, the window where the line is defined, opens and the line can be edited directly. The turning of the component by the robot is also displayed. The process can first be run as a simulation to verify a safe program. Flight safety aspects For safety reasons, airplane components have to fulfil high quality standards. So-called 'flying parts' are tested according to European (EN 9100), American (SAE AS 9100/9110/9120) and international norms. Not only are the product conformity and quality subject to these tests, but also the manufacturing process and its continuous documentation. The Horizon software user rights system, with login names and passwords and the ability to lock or hide certain fields and functions, allows precise definition and documentation of how the manufacturing process should run. The operator can activate or deactivate only the appropriate functions, ensuring that no critical parameters can be changed. During the machine programming process, the software also logs every button pressed, so that the required documentation is a natural by-product of the actual process. Two customers have already confirmed they will be using the new system, reports Haas Schleifmaschinen. Image: The Multigrind CB, the flagship of Haas Schleifmaschinen's grinding centers