CAD model hold many promises to be delivered during the design and manufacturing processes. It is the sole entity that decides the quality of the product as every single process is based upon this virtual model.
Developing a product model through CAD tools is something very common that you find in any manufacturing organization. Its use has become even more important as modern manufacturing techniques such as 3D printing is emerging rapidly.
However, additive manufacturing is still in its embryonic stage; with number of materials being tested to be printer-friendly, it is still not the right system to develop fully-functional parts that the traditional market requires. The subtractive manufacturing, on the contrary, still remain mainstream and as such it is crucial to understand the requirements of a CAD model that suits the CNC machining environment.
Points to Consider While Solid Modeling
For manufacturer, it has become mandatory to develop products directly from the CAD model; as such the accuracy in the model design is highly important to ensure that the end product looks similar to what is being actually desired. There are several points to consider while developing a 3D CAD Solid model for CNC machining.
It is always better to use the native file format when utilizing the CAD model for CNC machining. There are several CAM packages as well that offers formats that are friendlier with subtractive manufacturing. Apart from this, kernel files such as ACIS and Parasolids can be utilized in cases were native format doesn’t help. The best approach however, is to utilize neutral file format such as STEP or IGES. Although, IGES does require some additional options to manage in order to ensure that the model information is accurately transferred.
Avoid Surface Models
Surface models should always be avoided when used in conjunction with CNC machining as for the computer, surface model is the one with no thickness. It is always better to convert the surface model first to solid as the computer recognizes it as a model with thickness consisting of material between the two thickness boundaries.
Modern CNC machines are precise and highly accurate, as such, it is important to decide the tolerances appropriately. It is always good to develop a separate drawing file for machine shop with required details about the holes, slots, tolerances and surface finish required. Adding these details can help machine shop guys to pay more attention to the small details of the product design and ensure that the final product developed will be the one that you actually desired.
About the Author:
Gaurang Trivedi is engineering consultant at TrueCADD. He has applied his engineering expertise across several highly complex and big scale projects, consequently managing to flawlessly deliver as per the client requirements.