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CAD/CAM Software and High Speed Machining

5 min read

What is CAD/CAM Software?

Computer Aided Design. In reference to software, it is the means of designing and creating geometry and models that can be used in the process of product manufacturing. Computer Aided Manufacturing. In reference to software, it is the means of processing a designed part model, creating machine toolpath for its various components and creating an NC program that is then sent to a CNC Machine tool to be made. The CAD and the CAM are integrated into one system. CAD/CAM software is also highly referred to as CNC Software as well. The heavily searched term, “CNC Software” will also include pc-based cnc controller software as well. This is where you can turn your computer into a controller for your machine that supports up to 6 axis programs. An excellent example of this is Mach 3 controller software provided by ArtSoft.

The purpose of CAD/CAM is to automate and streamline CNC programming allow innovators, designers and CNC businesses to manufacture products, bringing them to market faster and more profitably than ever before. It is the concept of producing goods Faster… Smarter & Easier. live BBW cams

Traditional Offset versus High Speed Toolpaths 

The term, “Toolpath” is used to visually display and describe the route in which the CAM side of the software tells the cutting tool to machine the geometric regions of the part model. It’s the path that the tool takes when machining. Toolpath is going to be basically being defined by the part or areas that the user has chosen to machine, the size of the tool being used, the cutting regions for those tools and the type of machining strategy that is used. That is toolpath whether it’s for a mill, router, laser, burning machine, waterjet or cnc lathe. There is a lot of other data that is included in the creation of a NC Program that has to do with post processing parameters such as speeds and feed rates based on strategy, material and tool data and more. Machine controllers can be different in how they want to see the g-code for the program to be read properly by the controller. That is toolpath.

More than one toolpath is typically used to perform machining operations. Generally this will be a “Roughing” and a “Finishing” operation. Roughing is generally the first stage of machining.

This is where multiple step downs by the tool, remove the bulk of the material.

The second operation will be the finishing operation to complete the machining phase. There is also “Semi-Finishing”. An example of this would be the use of a Z-Level Roughing operation to remove the bulk of the material. Then a Z-Level Finishing operation to “semi-finish” the part and lastly a “Equi-Distant Offset contour” operation to finish the part off. By employing the use of High Speed toolpaths into your machining operations you can achieve excellent results faster than by using traditional offset toolpaths. Even in the world of 3D machining. BobCAD-CAM software offers a unique Advanced Roughing operation that includes the option to use an Adaptive High Speed machining technique. This was specifically added to give the programmer an advantage in roughing out 2D or 3D regions of a part, or the entire part.

Boundaries can be created and used to segregate the toolpaths into specific regions of the part, deep cavities or regions that require a smaller tool to machine. This would not be used to replace a REST operation. An advanced REST machining operation would be used as a part of the finishing process to clean up areas where the larger tools were unable to machine. Traditional offset toolpath has been the most common form of toolpath in use since the advent of CAM software. However, as more and more shops begin to use HSM they are trusting it more, becoming less criticaland beginning to enjoy the benefits of it. The goal of using a trochoidal form of machine path is to limit the number of collisions that the cutting edge of the tool has with the material, reducing chip load, better utilize the cutting tool itself by using more of it while taking deeper cut depths and all while at much higher speeds.

There are distinct differences in toolpath operations, planar, offset and high speed (HSM).

Planar (1) is the most fundamental of the three and is basically a back and forth slice across the material. Options for this style of toolpath would include the ability to machine in one direction (zig) and back and forth (zig-zag). You should also be able to determine a cut direction (climb or conventional), determine a “Lace Angle” parameter and a step over for the cutter. Some CAM systems will allow you to include a side allowance and a bottom allowance so that material can be left over for a finish pass. Tool lead-ins and lead-outs will often times be limited to a plunge, ramp or a spiral lead-in when using this type of strategy, each option definable through input parameters. In addition, compensation controls can be available for the finish pass. These options would include the availability of a complete tool database/library with tool crib and tool holder libraries as well as a complete material database/library. CAM software is designed to organize these strategies and associated variables. BobCAD-CAM has developed each machining operation into “wizards” that step the operator through the procedure so that the features are organized and no variable is left behind. This makes the process easy to understand and get through.

In addition, the CAM software allows for the overwriting of system tool parameters so that the experienced operator is not limited. These would include the use, or not, of system tools, tool height and offset values, speeds and feed parameters for the operation. These operations should also allow for the slowing down of the tool when entering an arc corner (when not using HSM).

Offset (2) is most common in cnc machining open or closed wall pockets and slots in a 2D/2.5 Axis (X, Y and Z step down) program. Very similar to planar, this type of operation in a CAM system is going to have the same variable inputs. The difference is whether you want to create an offset IN or an offset OUT. These concentric offsets will either start outside working their way toward the center of the specified cutting area or start in the center and work their way toward the outer wall or defined area.

 

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