For the milling of turbomachinery components, the hyperMILL® CAM software offers two special applications: the turbine blade package and the impeller and blisk machining package. Both applications now offer new milling strategies and optimised functions, enabling the use of thicker tools for greater process reliability and minimising tool paths for shorter machine times.

Impellers, blisks and turbine blades have complex geometry and therefore place high demands on the metal removal process. Until now, they were usually considered a job for specialists. The hyperMILL 5-axis applications guarantee simple, user-friendly programming, for which no specialist knowledge is required. This is because integrated automatic functions carry out many programming steps for the user. They reduce the number of parameters to be set and job steps to a minimum. The applications for the machining of turbine blades, impellers and blisks fit seamlessly into the hyperMILL operating philosophy. Users thus enjoy a high degree of flexibility when choosing the optimal machining strategy and tools. And there is no need for a second CAM system.

Complete from top to bottom
The turbine blade package enables complete machining, including root and tip platform structures. Up until now, the package comprised the following machining strategies: 3D roughing of any stock, 5-axis top milling for the milling of blade surfaces and 5-axis swarf cutting for the machining of fillets between blade and side surfaces, as well as the final swarf machining of the side surfaces from bottom or top. Added to this, there is now a new cycle for milling rest material areas and the variable radii between the turbine blade and the platform surfaces.

As with 5-axis swarf cutting, this new machining strategy allows the fillet radii between blade and side surfaces of the platform geometry to be automatically generated as a "rolling ball". These fillets often are not fully formed on one platform segment. In most CAD systems, they are very difficult or impossible to define. Thanks to the "rolling ball", however, a perfect transition between the individual turbine blades is produced merely at the click of a mouse. As the tool orientation does not "blindly" follow the vectors of the surfaces to be milled, smoother movements and therefore shorter machining times are achieved. In addition, the programmer can now define cross-fade paths to previous blade machining and therefore improve the appearance of the surfaces.

Successful in use
Within a short time dozens of companies worldwide have chosen the multiblade package. This shows that the CAM solution from OPEN MIND Technologies AG has successfully established itself in this relatively small market in a very short time. Integrated automatic functions and a straightforward graphical user interface enable simple programming, which not only is easy to learn, but also convinces experts. The proven collision check and avoidance features ensure the greatest degree of reliability at every stage of the machining task. Six machining strategies make the complete machining of impellers and blisks possible. The package includes optimised machining strategies for roughing, hub finishing, finishing of blades with point or flank milling, edge and fillet milling.

The machining cycles have been extended to include new tool orientation methods. Up until now, collision avoidance has only taken place following movement on the Z axis. With the new version, movement perpendicular to the camber line, a central curve with a blade, can be calculated. During finishing jobs with point milling, the programmer now uses an additional parameter to easily direct the movement of the tool to particularly narrow places. The tool movement thus generated creates space for the use of thicker and therefore more robust tools. Reliable milling with higher feed parameters and infeeds can thereby be achieved, thus minimising machining times.


Special roughing function for blisks
Due to stability problems when using long blades, blisks are often alternately roughed and finished during processing. The smoothing thereby is performed to support the aerodynamic behaviour, preferably in the direction of flow. The new roughing function makes it easy to define a pre-machining cycle, which is seamlessly followed by a finishing cycle.

For shorter tool paths
The distribution of paths offered the opportunity to further reduce machining times through even shorter tool paths. The stepover now ensures that the next possible path is taken, without additional infeed loops. The tool path is therefore itself shorter. At the same time, movement in the rotary axes is reduced. As a result, and depending on the material used, smoother tool paths for the best possible surface quality can be achieved.

About OPEN MIND Technologies AG
OPEN MIND Technologies AG is a leading developer of CAD/CAM software and postprocessors for designing and manufacturing complex moulds and parts. OPEN MIND offers an extensive range of products, from 2D feature-oriented solutions for milling standard parts through to software for 5-axis simultaneous machining. With over 7,500 licences sold across the automotive, tool and mould manufacturing, mechanical engineering and aerospace industries, OPEN MIND Technologies AG is represented in all the important markets in Asia, Europe and the Americas. OPEN MIND Technologies AG is a Mensch und Maschine company.