When utilising CAM software, one of the common questions is ‘why can’t it be more automatic?’. There are many people that would like to simply load a CAD model and have the CAM software determine the best way to mill it and then automatically program it. While this utopia world of CAM programming may not exist for all types of parts, that precisely is one of the goals of Automatic Feature Recognition (AFR). To sort out the common elements of the 3D model and using rules and templates, create the CNC code on the part.
Automatic Feature Recognition (AFR)
Solid models have all the necessary information to describe a part’s shape. Users do not need to waste time re-creating the part data just for the CAM system. Most prismatic parts comprise standard features such as holes, pockets and bosses. Where other CAM systems may require users to define geometry, create boundaries and then, specify cutting operations, AFR eliminates that. Typical 2D parts can often be programmed in just a few minutes, versus an hour or more.
Automatic vs interactive feature recognition
Users can typically run a wizard to automatically find and sort the different features within their parts. Typically, the input stock material size gives it an initial tool orientation, and the software then analyses the solid model and creates machinable features for machining. These features will then be listed and automatically sorted for logical machining operations. Alternatively, users that wish for fine control may select the features themselves interactively and sort them manually. Usually the best approach for any individual company is a combined approach of utilising AFR with some interactive selection or sorting of features for their personal preferences.
Once the features are defined, they are sorted for machining efficiency, and then they can be machined with strategies ideal to the properties of the individual feature. For example, an open pocket may be machined with a different strategy than a closed pocket. Or shallow bosses will be milled differently than tall ones.
Programming with features
Once the features are found or selected, a three-step process or a wizard can be used to program parts utilising the features. Users first select from a list of features and you may input information regarding the shapes and sizes. Next, users select a preferred machining strategy based on the information provided or go with the recommended strategy. The programmer can accept the strategies suggested based on the type of features for rough, semi-finished and finished passes, or make changes to fit the machining needs for that part.
Lastly, the combination of feature dimensions, stock material and cutting strategies are analysed, allowing the software to recommend the most efficient cutting tools, toolpaths, and feeds & speeds for each cutting operation. The programmer can choose the recommended tool or search for another tool in the library. Users can accept or change the recommended feeds and speeds.
Although automatic programming provides a good starting point, users should still retain control over how the software generates its CNC code. Users can set machining preferences ahead of time for the CAM software to apply to future works. Although it recommends tools, feeds, speeds, etc, the users can override it with their own preferences at any time.
From different work offsets
AFR can extend beyond using just the tool axis and can be utilised in multiple setup orientations to find all features on a part, regardless of the orientation. These will then be sorted by the workplane and feature type. Users can then decide the order of various orientations and program the features accordingly.
Based on the user’s manufacturing knowledge, AFR intelligently makes decisions for them. It automatically selects the tools, stepover, stepdown and more, providing programming consistency, utilising parameters out of the box, or those that they customise for their own operations. These parameters, among others, form a part of the operations. As a user creates multiple features, the software dynamically updates their process planning, providing an optimal machining order, based on what they want to achieve.
Part changes are an inevitable fact of working in a job-shop. If a part has already been analysed and programmed, then the part geometry changes, one can simply compare the updated part to the original. Feature list will automatically update for the changes, and the generated CNC code will update. This strategy is not only useful on part changes, but also for milling similar parts, or a family of similar parts. Simply utilise AFR to sort and program one part, tweaking with the user’s personal preferences, then apply all of those same strategies to a similar part, automatically.
Better utilisation of workforce
Utilising AFR allows the workforce to be utilised in a more efficient manner. AFR allows for standardisation of the entire machining process. The best expert machinists could set up the machining templates; and all programmers, regardless of the experience, would be able to utilise their knowledge and experience. This allows for consistency in the user’s to finish, tool life and overall quality of parts produced.
Retaining & simplifying processes
AFR and feature-based machining can simplify the machining processes of certain parts typical to the job-shop, allowing for programming to be completed in minutes instead of hours. Knowledge gained during the process can be retained for future jobs, for the user’s individual preferences.
Courtesy: Originally appeared on Autodesk.com