Solid modelling for complex machining

Solid Modelling derives its name from the fact that a solid modeller creates an object called a solid, or body, to represent a part. Not only do solid models represent the vertices, edges and surfaces of the part, but it can also determine whether any point in space is either inside or outside the material of the part. This sounds simplistic, but has powerful ramifications. It allows a solid modeller to automate many of the decisions that a surface modeller relies on the user for, such as which sections of a part to keep and which to trim away.

Solid modelling also provides an extremely simple means to create complex objects - Boolean operators where the basic operation is to "add", "subtract", or "intersect" two bodies, resulting in the creation of a new body. Starting with a simple body, such as a sphere, a cube, an extrusion or revolution of a shape, Boolean operators allow complex forms to be built up. No user input is required to determine the portions to leave or remove. Behind the scenes, the solid modeller automatically trims off unneeded portions or combines portions into a new model. It ensures that the resulting model maintains all model consistency rules and can be used for subsequent modelling operations. While all this is going on, though, the users are not exposed to that level of detail.

Machining solids
All the pretty pictures in the world will not create a machined part. For this, we need CAM capabilities. Solid models offer a complete and unambiguous part definition. This allows CAM software to automate much of the NC programming process, by providing highly efficient roughing and finishing functions to apply to the entire model. The ability to machine the entire model with multiple tools in a single step is a significant time saver. Advanced solid machining CAM systems can provide "material only" machining, where each tool only removes the material left behind by previous tools. Gouge protection and clamp avoidance are other useful capabilities.

Solid models provide just such a part definition. This technology can be used to develop knowledge-based machining CAM systems. A knowledge-based machining system allows users to define their preferred machining methods, which the software will then apply to a solid model in order to determine a specific machining process and create the resulting toolpath elements. This is useful in both simple 2.5-axis parts as well as in complex 3-axis surface machining.

Solid model machining can create a finished part program significantly faster than other technologies. It is ideally suited for a number of NC shop tasks, including defining complex parts from a blueprint, building solid models from imported wireframe and surface data, and importing solid models from the prime customer and machining them directly.