CAM software continues to become more automated, more tightly integrated with design software and easier to use.
Every year, CIMdata issues an NC Software Market Assessment Report describing technology trends, economic trends, and specific product offerings within the CAD/CAM marketplace. The following excerpt from that report summarizes some important technology developments affecting CAD/CAM software today. If your company is considering an upgrade to its CAM capabilities, check this list for features you may want to evaluate for your own application as well as discuss with potential software suppliers.
CAM software is evolving from the use of basic steps, such as drawing a line or creating a fillet, to process automation that may be application-specific. This latter approach is better able to consider the full needs of a particular type of user. Examples relate to mold and die operations. For instance, software wizards can be used for processes such as electrode design or tooling assembly creation. One CAM supplier offers a range of applications covering core and cavity design, mold base design, electrode design and machining, and mold machining. Other companies have introduced application suites for design and cutting of progressive dies.
Design Data Analysis
Some CAM systems provide an analysis function to examine incoming electronic models for non-manifold conditions and also to analyze design data for manufacturability. The software detects overlapping surfaces, surfaces left out, twisted surfaces, gaps, holes, negative draft angles and undercuts. Problem areas can be displayed for further user action. In some cases the problem areas can also be fixed automatically, with the correction accomplished by forcing tangency and by turning sharp corners into fillets.
Speed in toolpath generation, along with the tool path’s ability to provide fast machining, is becoming increasingly important. As most products now have adequate functionality, added speed can be more important than new features. Some CAM companies are evolving to a new toolpath engine primarily to obtain added performance.
With the continuing demand for ease of use and increased productivity, greater automation is being embedded into all aspects of CAM products, from the user interface to post processors. The software is doing more, and the user is doing less. Just a few examples include intelligent user interfaces; programming guidance; commands incorporating multiple steps; automatic re-machining; and automatic selection of cutting parameters, tools and tool paths.
Machining On A Hybrid Model
Most CAM systems now machine on a tessellated solid or surface model. Machining on a tessellated model, as compared to machining directly on a solid or surface, is a commonly employed technique to minimize gouges and to increase machining performance. The primary benefit of the tessellation modeling and machining technique is that it is mathematically simpler than working with surfaces. It allows the software to calculate tool paths and display shaded 3D images quickly. It also allows a complex surface to be represented as a single entity. It avoids missing data, or ambiguous data, when working from translated surfaces and solids. It also reduces the likelihood of gouging when crossing surfaces in multi-surface machining.
Automatic Feature Recognition
Feature recognition capability lets the software examine a model and identify its specific features for subsequent processing. Typically, automatic feature recognition is used with standard machined features such as holes, slots and pockets, but user-defined features are also normally permitted. The ability to recognize these features is a component of knowledge-based machining, in which machining knowledge is stored so that the software can apply it automatically. By quickly identifying a part model’s geometric features, the CAM software can call upon specific machining processes that have been stored in a database in order to generate the appropriate lines of NC code. The same capability can also be important to non-machining applications such as generating cost quotes or creating CMM inspection programs.
Capturing Best Practices
This is another component of knowledge-based machining. A set of machining rules—based on the workpiece material, the geometric features and the operations to be performed—can be defined by the software’s users. These rules can then be applied automatically to current and future machining tasks. As a result of this approach, machining methods can be kept consistent, process variables can be minimized, tooling can be optimized, best practices can be captured, and programming time can be reduced substantially. One CAM package providing this capability offers a graphical flow charting tool to assist users in building their machining strategies.
Support Of High Speed Machining
Software support of high speed machining has become mandatory in mold and die machining. Most die/mold shops now employ this technique. The software to support this technology must provide for fast and efficient transfer of data, smooth tool movement that minimizes any sudden change in direction, a constant chip load to maximize the life of the cutter, and other features necessary to produce gouge-free parts with a high-quality finish.
Currently, high speed machining is primarily applied to three-axis milling. The combination of high speed machining and five-axis milling is relatively rare, at least in die/mold machining. However, some machine tool builders have begun to offer high speed five-axis machines specifically for die/mold work. In time, CAM software suppliers will be required to support high speed machining on these more complex machines.
Feed Rate Optimization
Typically, high speed machining is limited to very small axial cut depths in order to achieve good surface finish while avoiding damage to the cutter, workpiece or spindle. Feed rate optimization software can be employed to achieve better cutting efficiency with greater axial depths at high feed rates, while protecting the tool, machine and work in those few places where the chip load momentarily increases. Anticipating where the chip load is too great, the software adjusts the feed rate to a more reasonable level in these areas. It then returns the machine to the higher feed rate when the chip load permits.
Step Reduction Milling
This feature automates and optimizes the Z-level rough milling process when machining the complex multiple-surface geometries that are often encountered in mold and die machining. The feature manages the move from larger to smaller steps and from larger to smaller tools for improved efficiency. Large tools are used to take large steps to remove the maximum amount of material, then the same tool may be used to semi-finish instead of a smaller tool being used to clean up. The smaller tool is then used only in those areas where a larger tool will not fit. Roughing steps for the larger tool are reduced down to the point of the next tool’s maximum depth of cut.
Integrated Verification And Post Processing
Verification software and post processing are being integrated with toolpath generation. The user may operate with toolpath verification and generation running concurrently on the screen, so the effect of toolpath changes can be viewed almost instantaneously. Also, the integration of the post processor into the toolpath generation module is becoming more common.
Coming: Full Automation
Ultimately, CAM software will have the potential to run completely automated and unattended, converting part models into programs. By using knowledge-based machining concepts to embed machining intelligence into the CAM software, it will be possible for the software to automatically select the machining processes, parameters and cutting tools, and then automatically create the final program. The same software will also be able to learn from experts in each shop, with machining intelligence updated to reflect those experts’ own preferred manufacturing methods so that their techniques appear in the way that future parts are machined.
About the author: Alan Christman is vice president of CIMdata, Inc., of Ann Arbor, Michigan. His column “CAD/CAM Outlook” appears in this magazine in even-numbered months.