High Speed Roughing NX-plugin

Introduction

The high Speed Roughing CAM module is a plugin for Siemens PLM NX. The CAM module utilizes a unique algorithm is for the calculation of adaptive toolpaths for high productivity milling. These toolpaths are designed to control cutting tool engagement with the material in all situations. The ability to control tool engagement allows for highly productive methods of material removal.

Physics Based Toolpaths for High Speed Machining

High-speed machining is the preferred method of material removal for soft metals such as aluminum. Typically, an engineering approach is taken to define cutting parameters for each tool. This approach includes analysis of vibration characteristics of the cutting tool while loaded in the machine. From this information and many complex calculations, a recommendation can be made for the most productive cutting parameters for a stable cut (no chatter). Software packages such as MetalMax TXF make this vibration measurement and complex calculations a simple process for users. This is usually an off-line process that is completed prior to NC programming. The cutting parameters will typically be selected for the optimal radial depth of cut and documented for NC programmer reference.

The Physics-based Toolpath module allows the NC programmer to combine the method of cutting parameter selection for high-speed machining and NC programming in one process. With the use of MetalMax TXF, a data file is computed and output in XML format. This data file includes a description of the cutting tool vibration characteristics for all widths and depths of cut. This detailed description allows selection of the most efficient stable cutting parameters in real time during the NC programming process. This selection method integrated with the adaptive toolpath calculation allows for more efficient material removal than with previous techniques.

Physics-based Toopaths for Hard Metal Machining

Surface Speed

When machining hard metals, one of the primary concerns is heat created during the chip forming process. The main contributor to heat generation is the speed the cutting tool passes through the part material called surface speed. Each combination of tool and part material has a narrow range of surface speeds that allow for acceptable cutting tool life. The second factor of heat generation is radial depth or tool engagement. With typical tool paths, the worst case radial depth is a full slotting condition where the cutting tool is engaged for 180 degrees of rotation. This forces the surface speed to be selected for this worst case condition. When using adaptive toolpaths from the Physics-based Toolpaths module, the worst case radial depth is controlled by input from the NC programmer. Reducing the radial depth allows for much higher than typical cutting speed selections.

Larger Axial Depth

Another concern during machining of hard metals is chatter caused by unstable cutting depths. The stable cutting depth is decreased because of the increased cutting forces from hard metals. When using typical toolpaths, a stable axial depth is always limited by the worst case full slot radial depth. When using adaptive toolpaths, since the radial depth of cut is controlled, the stable axial depth of cut is increased as the radial depth is decreased. This allows for cutting tool wear pattern to be spread along the full length of the tool.

Another advantageous use of adaptive toolpaths is the selection of the number of teeth based on the radial depth of cut. The number of teeth can be increased as the radial depth decreases.