CAD/CAM is one of the most ignored subjects in Mechanical Engineering by students who are preparing for GATE or UPSC ESE. The primary reason for this is that, the subject is so vast and there are very scare resources available to prepare concisely for the sake of any examination. In this article, we will introduce the subject of CAD/CAM from the point of view of its application.
- Computer-Aided Design (CAD) is the technology concerned with the use of computer systems to assist in the creation, modification, analysis, and optimization of a design.
- Computer-Aided Manufacturing (CAM) is the technology concerned with the use of computer systems to plan, manage, and control manufacturing operations.
- Computer-Aided Engineering (CAE) is the technology concerned with the use of computer systems to analyze CAD geometry, allowing the designer to simulate and study how the product will behave.
In general, a CAD package has three components: (a) Design, (b) Analysis, and (c) Visualization, as shown in the figure below. A brief description of these components are as follows:
- Design: Design refers to geometric modeling, i.e. 2D and 3D modeling, including drafting, part creation, creation of drawings with various views of the part, assemblies of the parts etc.
- Analysis: Analysis refers to finite element analysis, optimization and other number crunching engineering analysis. In general, a geometric model is first created and then the model is analyzed for loads, stresses, moment of inertia and volume etc.
- Visualisation: Visualisation refers to computer graphics, which includes: rendering model, creation of pie charts, contour plots, shading a model, sizing, animation etc.
CAM is the next stage if CAD. A part created in CAD can be downloaded and manufactured, without a human hand touching the part. The process is called CAM, and involved CAD, Networking and NC Programming, as shown below.
CAD software are written in FORTRAN and C languages. FORTRAN provides the number crunching, where as C language provides the visual images. Early CAD packages were turnkey systems, i.e. the CAD packages were sold as an integrated software and hardware package, with no flexibility for using second vendor hardware. These systems, which were available in 1970s and 80s, were based on 16 bit word, and were incapable of networking. The modern CAD software uses the open architecture system, i.e. software vendors do not design and manufacture their own hardware. Third party software can be used to augment the basic CAD package.
Networking is an important consideration in applications of CAD software. A model by one engineer must be readily accessible to others in an organization whic his linked by a LAN or other means. The designer, analyst, management, marketing, vendor, and others generally share a model.
We can run CAD software on three different platforms: Mainframe, Workstation and PC. When the CAD programs first became available they could only be run on a mainframe computer. However, as the PCs have become faster and cheaper, almost all the CAD vendors have introduced a version for their CAD software that will effectively run on a Pentium or higher computer. Currently, the most popular platforms are PCs and Workstations.
The structure of CAD/CAM
Main constituents of CAD tools: