Computers have increasingly become an integral part of the design and manufacturing environment. The engi­neering professional and support staff use computers extensively for the production of working and design drawings. These drawings are created using a variety of different drafting and design programs designed to produce two-dimensional and/or three-dimensional (length, width, and depth) drawings, see Figure 27.1 and Figure 27.2.

In addition to drafting and design, software is also available for the creation of three-dimensional solid models and photo realistic renderings, see Figure 27.3. Computer software is also available to translate work­ing and design drawings into machine instruction to aid in the production of the designed part.

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Examples of computer programs that are used extensively in manufacturing are:

■ Computer Assisted Machining (CAM)

■ Computer Integrated Manufacturing (CIM)

■ Computer Numerical Control (CNC)

■ Computer Aided Design/Computer Aided Manufacturing (CAD/CAM)

■ Computer Aided Drafting and Design (CADD)

■ Computer Aided Drafting or Computer Aided Design (CAD)

The primary focus of this unit is to introduce the basics of Computer Aided Drafting (CAD).

Note that Figure 27.1 and Figure 27.2 include pictorial (isometric) drawings to assist in identifying the relationship of orthographic views to one another, thus expediting the interpretation of the drawings.

CAD programs provide the user with the ability to store and retrieve graphics and text information. The drawings produced by CAD can be used in a variety of different ways. For example, they can be used as an overlayment for detecting deficiencies and interference.

Three-dimensional drawings produced by CAD are often referred to as models. Models are often used to perform complex engineering stress analysis. In addition, three-dimensional models are often used to check tolerances and fits of complex assemblies. These capabilities, along with numerous others, have made this technology a welcomed addition to the engineering community. CAD has improved drawings standards and quality by allowing the user to build libraries of commonly used symbols and parts, thus allowing the user to merely insert these components instead of recreating them every time one is needed. CAD has improved the
accuracy of engineering drawings. Most CAD drawings are created at a scale of 1:1 (full) and printed at the final desired scale.

These capabilities have not only decreased the amount of time required to produce and check engineering drawings, but have also improved the time required to design and manufacture parts and assemblies.

Models produced by CAD software can be loaded and analyzed by CAD/CAM programs to produce machine instruction for CNC (Computer Numeric Control) equipment, thus allowing for the production of part and components with minimal intervention by a machine operator.