Quickly Program Complex Blisks And Impellers

Delcam offers a new module for its PowerMill CAM system that enables 30-minute programming for five-axis machining of complex blisks and impellers,the company says. To generate the CAM program, the user divides the CAD geometry between the shroud, hub and blade, as well as the splitter blade, if appropriate. Then, the programmer chooses tools from the database within the software and specifies the types of leads and lifts. Next, the user decides whether to rough either pocket-by-pocket or level-by-level. The latter option involves more air moves but avoids deflection of thin blades, which can result from machining pocket-by-pocket. 


Users can also choose whether to finish by machining the opposite faces of the pair of blades across a pocket or by machining around each blade. Finally, the predominant tool angle must be set, typically normal to the hub or to the center line of the part. During the calculations, the software adjusts this angle by the minimum amount required to maintain adequate clearance while providing smooth tool-axis movement.


The software will then calculate the three tool paths needed to machine the item: a roughing tool path to remove the bulk material and two separate finishing tool paths for the blade and hub. The software issues a warning if the roughing cutter will not remove enough material for safe finishing. In this case, a stock model can show the remaining material. This allows the user to choose to either reduce the size of the roughing cutter to enable better access and increased material removal or to create an additional semi-finishing tool path to leave enough material for finishing.


If the blades are evenly spaced, the software will count the number of blades and produce a set of tool paths in one operation. This can further speed calculation times, the company says. If the blades are not evenly spaced, tool paths must first be produced for a single blade and then copied around the hub at the appropriate angles.  

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