New roughing and finishing strategies in Delcam’s PowerMILL
The 2012 R2 version of Delcam’s PowerMILL CAM system for high-speed and five-axis machining includes new and enhanced strategies for both roughing and finishing. Full details of both the 2012R1 and R2 releases, including videos demonstrating the new functionality, can be seen on www.delcam.tv/pm2012/lz
The most important of the new strategies is step cutting within area clearance. Modern roughing tools are capable of removing material more quickly by using larger stepdowns. The disadvantage of this approach is that large terraces can be left on the part. These steps can be removed by rest machining with a smaller tool.
An alternative approach is to step back up the terrace with the existing large tool, adding extra cuts at intermediate levels. This results in more material being removed, using the same tool within the same toolpath.
The rate of material removal can be optimised by increasing the feed rate automatically as the depth of cut gets smaller. This reduces the overall machining time.
Another important addition is the ability to use polar milling when programming machines with a rotary table. With polar milling, the x or y axis is locked and the third axis of movement provided by the c axis. This can be more efficient when drilling or milling features arranged around a centre of rotation. It can also produce smoother movement and better surface finish with spiral machining.
Another enhancement produces an improved toolpath when using automatic verification on a toolpath to prevent a collision by the shank or the toolholder. In the previous version of PowerMILL, the tool would be retracted to a safe height whenever a collision was possible and then returned to the part once it was safe to continue machining. Now, PowerMILL generates a continuous toolpath that removes as much material as possible, while still avoiding any collisions. The elimination of the retract moves shortens machining times and gives an improved surface finish, while the continuous cutting reduces the change of load on the tool so increasing its life.
The use of stock models to optimise machining efficiency is also well established within PowerMILL. This functionality is now available from a new dedicated toolbar that makes it much easier to use and more consistent with other PowerMILL functionality. All the parameters related to a particular stock model can now be accessed from a single form. In addition, it is now possible to drag and drop tools or toolpaths into a stock-model folder prior to stock-model calculations.
Work has also continued to improve the macro language within PowerMILL that can be used to automate any routine or repetitive calculations. A new macro debugger has been added that makes it easier and quicker to identify any errors in a macro. Furthermore, the creation and editing of larger, more complex macros has been made easier with a new option to set breakpoints within the macro and the ability to view the contents of the variables in a separate watch window.