Computer-aided manufacturing varies from industry to industry, and among companies within industries. Different manufacturers are at different stages in their use of automation technologies. Consequently, it is not possible to list all available CAM jobs. Instead, here are in-depth stories of several people who work with CAM.
Before we can look at the effects of CAM on employment opportunities, we need to think about what we mean by computer-aided manufacturing. The April 1984 report from the U.S. Congress, Office of Technology Assessment, (Computerized Manufacturing Automation: Employment, Education, and the Workplace), says it includes robots, computerized machine tools, and flexible manufacturing systems. Industrial robots, says the report, are manipulators which can be programmed to move objects along various paths. Numerically controlled (NC) machine tools are devices that cut or form a piece of metal according to programmed instructions about the desired dimensions of a part and the steps for the process. Flexible manufacturing systems (FMS), combine a set of workstations, usually NC machine tools, with robots or other devices to move material between workstations, and operate under central computer control. And the use of these "programmable automation" tools for design, manufacturing, and management in an integrated system, with maximum coordination and communication between them, is called computer-integrated manufacturing (CIM, pronounced "sim")
Numerical Control Machines
In the 1940s and 1950s, numerical control (NC) technology was pioneered and developed by the U.S. Air Force, primarily to help make complex parts for aircraft. Producing them reliably and economically with manually-guided machine tools was difficult; NC technology solved most problems.
Before that time, a skilled worker who wanted to cut and form a metal part used a conventional machine tool, shaping the part by hand...producing the desired shape by moving either the piece being worked on, or the head of the cutting tool. All relevant aspects of the machining process, including the speed of the cut and the flow of coolant, were controlled by the machinist.
In older NC technology, a programmer writes instructions for the machine at a terminal, which punches holes in a paper or special plastic tape. Next, the tape is fed into the NC controller. The holes represent commands, which are transmitted to the motors that guide the machine tool.
These machines are programmable. They can easily be set to make a different part when a different punched tape is fed to the machine. Because the machine itself moves its cutting head and adjusts its own coolant, it is considered automated. Most of these machines, however, require an operator.
In general, says the OTA report, NC operators supervise the machines' operation. They can override the controls to make changes in the rate of motion of the cutting tools and the rate of cut. They look at the quality and dimensions of the cut. If the machine tool seems to be wearing out, the operator can stop the machine and replace the tool. NC operators also check the machines and stop them if there is an accident or damage, such as a blocked line for coolant.
Data from the 13th American Machinist Inventory, American Machinist, November 1983, indicate that total numbers of Numerically Controlled machine tools used in United States metalworking grew slowly from the late 1950s till 1974 or 1975. At that time, says the Inventory, there were around 30,000 such machines.
When microprocessors began to be available for use in the controller, the numbers of NC tools grew much more rapidly. By 1983, the Inventory says, there were over 100,000 such machines.
Newer machines that use minicomputers often have a screen and keyboard, so NC programs can be written or edited at the machine. In larger systems, a bigger mini- or mainframe computer is used to program and run more than one NC tool at the same time. A technology called distributed numerical control gives each machine tool its own microcomputer, but links the systems to a central computer that controls them.
Computerized numerically controlled (CNC) machines let the machine operator edit the program right at the machine, instead of having to send a tape back to a programmer, who would make the necessary changes. An alternative, however, is to program "off-line," so that factories don't tie up expensive machines while programs are keyed in. Instead, the programming is done away from the machine. When the programming is finished, it's loaded into the machine control, and the machine starts running again.
Such machines, however, are expensive. Substantial training is required to use them. And the specialized computer language (APT or Automatically Programmed Tools) that most NC machines use is complicated and difficult, especially for workers outside the aerospace industry, according to an unpublished 1983 paper prepared for the Office of Technical Assessment.