Lesson 7

Read the text: Computer-Aided Design and Computer-Aided Manufacturing

Computer-aided design (CAD) involves creating computer models defined by geometrical parameters. These models typically appear on a computer monitor as a three-dimensional representation of a part or a system of parts, which can be readily altered by changing relevant parameters. CAD systems enable designers to view objects under a wide variety of representations and to test these objects by simulating real-world conditions.

Computer-aided manufacturing (CAM) uses geometrical design data to control automated machinery. CAM systems are associated with computer numerical control (CNC) or direct numerical control (DNC) systems. These systems differ from older forms of numerical control (NC) in that geometrical data are encoded mechanically. Since both CAD and CAM use computer-based methods for encoding geometrical data, it is possible for the processes of design and manufacture to be highly integrated. Computer-aided design and manufacturing systems are commonly referred to as CAD/CAM.

CAD had its origins in three separate sources, which also serve to highlight the basic operations that CAD systems provide. The first source of CAD resulted from attempts to automate the drafting process. These developments were pioneered by the General Motors Research Laboratories in the early 1960s. One of the important time-saving advantages of computer modeling over traditional drafting methods is that the former can be quickly corrected or manipulated by changing a model's parameters. The second source of CAD was in the testing of designs by simulation. The use of computer modeling to test products was pioneered by high-tech industries like aerospace and semiconductors. The third source of CAD development resulted from efforts to facilitate the flow from the design process to the manufacturing process using numerical control (NC) technologies. It was this source that resulted in the linkage between CAD and CAM. One of the most important trends in CAD/CAM technologies is the ever-tighter integration between the design and manufacturing stages of CAD/CAM-based production processes.

The development of CAD and CAM and particularly the linkage between the two overcame traditional NC shortcomings in expense, ease of use, and speed by enabling the design and manufacture of a part to be undertaken using the same system of encoding geometrical data. This innovation greatly shortened the period between design and manufacture and greatly expanded the scope of production processes for which automated machinery could be economically used. Just as important, CAD/CAM gave the designer much more direct control over the production process, creating the possibility of completely integrated design and manufacturing processes.

The rapid growth in the use of CAD/CAM technologies after the early 1970s was made possible by the development of mass-produced silicon chips and the microprocessor, resulting in more readily affordable computers. As the price of computers continued to decline and their processing power improved, the use of CAD/CAM broadened from large firms using large-scale mass production techniques to firms of all sizes. The scope of operations to which CAD/CAM was applied broadened as well. In addition to parts-shaping by traditional machine tool processes such as stamping, drilling, milling, and grinding, CAD/CAM has come to be used by firms involved in producing consumer electronics, electronic components, molded plastics, and a host of other products. Computers are also used to control a number of manufacturing processes (such as chemical processing) that are not strictly defined as CAM because the control data are not based on geometrical parameters.

Exercise 1. Read and memorize using a dictionary:

drafting, data, host, affordable, decline, linkage, attempt, drilling, milling, grinding, semiconductor, advantage, shortcoming, innovation, shorten, overcome, source, create, simulation

Exercise 2. Answer the questions:

1. What systems enable designers to view objects under a wide variety of representations?

2. What innovation greatly shortened the period between design and manufacture?

3. What did the third source of CAD development result from?

4. What does computer-aided manufacturing use geometrical design data for?

Exercise 3. Complete the sentences with the suggested words: ease, undertaken, enabling, shortcomings, linkage

The development of CAD and CAM and particularly the _____ between the two overcame traditional NC _____ in expense, _____ of use, and speed by _____ the design and manufacture of a part to be _____ using the same system of encoding geometrical data.

Exercise 4. Ask questions to the given answers:

1. Question: _______________________________?

Answer: CAD systems enable designers to view objects under a wide variety of representations and to test these objects by simulating real-world conditions.

2. Question: _______________________________?

Answer: The use of computer modeling to test products was pioneered by high-tech industries like aerospace and semiconductors.

3. Question: _______________________________?

Answer: Computers are also used to control a number of manufacturing processes that are not strictly defined as CAM because the control data are not based on geometrical parameters.

Exercise 5. Match the left part with the right:

1. The use of computer modeling to test products	a) that geometrical data are encoded mechanically.
2. It was this source that resulted	b) serve to highlight the basic operations that CAD systems provide.
3. These systems differ from older forms of numerical control (NC) in	c) in the linkage between CAD and CAM.
4. CAD had its origins in three separate sources, which also	d) was pioneered by high-tech industries like aerospace and semiconductors.

Exercise 6. Learn the following definitions:

Three-dimensional space is a geometric 3-parameters model of the physical universe (without considering time) in which all known matter exists.

Computer-aided design is the use of computer systems to assist in the creation, modification, analysis, or optimization of a design.

Direct numerical control is known as distributed numerical control (also DNC), is a common manufacturing term for networking CNC machine tools.

A semiconductor is a material which has electrical conductivity to a degree between that of a conductor (such as copper) and that of an insulator (such as glass).

Exercise 7. Compose a story on one of the topics (up to 100 words):

“Computer-aided design”

“Computer-aided manufacturing”

“The sources of CAD”