The designers of mechanical products are generally not experts in machining. Therefore, they often design parts with inherent machining difficulties. Such shapes with machining difficulties are usually detected by machining experts in the later stages of manufacturing preparation. These shapes are then reported to the designer and finally resolved by modifying the part shape. This reworking process inevitably causes considerable time loss. Although various design for manufacturability (DFM) tools have been developed to avoid such problems, their use in practice remains limited due to their lack of versatility.  
Recently, a new type of manufacturing business offering small machine parts has emerged, for example, Protolabs and Misumi’s meviy. In this business, orders are received through the Internet using the CAD models. The necessary cost and processing time are immediately estimated at the time of receiving order. Machining methods are predetermined in this business and are usually limited to conventional milling. The available milling tools are also standardized. Parts that are manufactured using the standard milling process can be produced at a very low cost. On the other hand, in the case of parts that cannot be machined using the standard method, the machining should be carried out in a special process. Consequently, both time and cost increase considerably.   
Currently, machining experts check whether parts can be manufactured using the standard process based on the CAD model being sent. However, using this manual method makes it difficult to determine problems in a short time. Additional problems such as difficulties in preparing experts for the checking task and coping with changes in the production facility occur. To distinguish the parts that cannot be machined using the standard method immediately, the company needs a software tool for the automatic analysis of the manufacturability of the parts.  
To cope with such necessities, we develop a novel piece of software to detect difficult-to-machine shapes in a part automatically. A designer can use this software to determine the shape that is difficult to produce by themselves using the conventional cutting and can modify the shape on the spot. In the Internet-based part manufacturing business, the same software can be used to check whether the given part can be produced using the standard milling method predetermined in the company.   
Our system is based on “milling simulation” and analyzes the manufacturability of parts by repeatedly executing the machining simulation. For example, it detects a shape that cannot be produced using the prepared cutting tools by executing milling simulations with the tools, and the visualizing shapes remain unmachined after all simulations. Based on this result, design improvements are encouraged by the designer, or the necessity of additional machining time and cost are reported to the engineer during the cost estimation task.  
High-speed cutter path generation and milling simulation are key to realizing such technology. In this study, acceleration of the processing is realized using graphics processing unit (GPU) technology, and the difficult-to-machine shapes are extracted in several minutes using a standard PC.  
 


Milling Simulation-Based Method to Evaluate Manufacturability of Machine Parts

Division / Sponsors: 
Design Engineering Division and Computers & Information In Engineering Division


Paper Proceedings: https://asmedigitalcollection.asme.org/IDETC-CIE/IDETC-CIE2020/volume/83907

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