CAD and CAM (computer-aided manufacturing) are used at every stage of a productís life. From the initial product idea to quality control and product refinements, CAD makes manufacturing tasks easier. The manufacturing process is shown at the right. This article discusses how CAD is used at each step of the manufacturing process.
The first stage of manufacturing is to identify the basic product idea. Designers draw several concepts using basic CAD commands such as LINE, CIRCLE, ARC, and RECTANG. These simple shapes can be used to provide a basic idea of what designers think the product should look like. At this stage, few details are included. Because the ideas are created in CAD drawings, they are easy to change and refine during the rest of the manufacturing cycle.
After a concept has been selected, CAD is used to design the product. Design engineers create a 3D CAD model that represents the product in its entirety. Every hole and feature is represented at this stage. The engineers decide how parts should fit together when they are assembled.
During the design of a product, the engineer is often asked to perform some analysis. The engineer uses mathematical equations to determine how the product should react during testing. One of the greatest advantages of a solid model created in CAD is that the model can be tested using computer simulations. It is faster and far less expensive to simulate the test using a computer model than it would be to produce and test a physical prototype. Analysis may include testing to answer the following questions:
Detail Drawing Generation
- What is the effect of increased or decreased temperatures on the part?
- How much force is generated when the part falls?
- How much weight or force can the part withstand?
- What stresses are caused by assembly?
- What stresses are caused by moving the part or assembly?
In addition to the 3D model, engineers use CAD to create 2D detail drawings of every part and assembly. A part is a representation of a single component of a product. An assembly is a collection of parts that are fitted together using screws, pins, or other fasteners. The detail drawings produced at this stage provide guidance for later stages of manufacturing. They can be stored in the computer and edited or referred to later.
As the design is produced, engineers often suggest improvements and changes to the design. When an improvement is identified, the CAD data is altered and new detail drawings are produced.
Manufacturing engineers use information from the CAD models and detail drawings to manufacture the component. This process is referred to as CAD/CAM. A CAM program translates the CAD part information into a code that is recognized by computerized manufacturing machines. The machines use the CAM information to guide drill bits and tools to produce the shapes, holes, and contours of the parts. The manufacturing engineers also use CAD to produce diagrams and pictures that show other manufacturing personnel what steps need to be performed to produce and assemble the parts. These are called visual aids and process sheets.
After a part is manufactured, it needs to be checked or inspected to make sure that it was created properly. The CAD drawings are used to compare the design information to the actual dimensions on the finished part. Some parts must be produced very accurately; others may have looser production tolerances. In all cases, there must be some way to check the finished parts to make sure that the product conforms to the plans.
Testing and Refinement
Products can always be improved. Even though some testing and refinement were done at an earlier stage of manufacturing, they are often done again as the product becomes more mature or even after the product is in production. The CAD system is once again used to simulate tests as well as to create and update any manufacturing information.