AUTOMATION

AUTOMATION

      Automation is per forming certain tasks, previously done by people, by machines only. The sequences of operations  are controlled automatically. The most familiar example of a highly automated system is an assembly plant for automobiles or other complex products.

The term automation is also used to describe nonmanu facturing systems in which automatic devices can operate independently  of human control. Such devices as automatic pilots, automatic telephone equipment and automated control systems are used to perform various operations much  faster and better than could be done by people.

Automated manufacturing had several steps in its development. Mechanization was the first step necessary in development of automation. The simplification of work made it possible to design and build machines that resembled notions of the worker. These specialized machines were motorized and they had better production efficiency.

Industrial robots, originally designed only to perform pie tasks in environments dangerous to human workers, are now widely used to transfer, manipulate, position both light and heavy workpieces performing all the functions of a transfer machine.

In the 1920s the automobile industry for the first time an integrated system of production. This method of  production was adopted by most car manufacturers and became known as Detroit automation.

Tne feedback principle is used in all automatic-control mechanisms when machines have ability to correct themselves. The feedback principle has been used for centuries. An outstanding early example is the flyball governor, invented in 1788 by James Watt to control the speed of the steam engine. The common household thermostat is another example of a feedback device.

Using feedback devices, machines can start, stop, speed flow down, count, inspect, test, compare, and measure.

These operations are commonly applied to a wide variety of production operations.

Computers have greatly facilitated the use of feedback in manufacturing processes. Computers gave rise to the development of numerically controlled machines, motions of these machines are controlled by punched paper or magnetic tapes. In numerically controlled machining centres machine tools can perform several different machining operations.

More recently, the introduction of microprocessors and computers has made possible the development of computer-aided design and computer-aided manufacture (CAD and CAM) technologies. When using these systems a designer draws a part and indicates its dimensions with the help of a mouse, light pen, or other input device. After the drawing has been completed the computer automatically gives the instructions that direct a machining centre to machine the part.

Another development using automation are the flexible manufacturing systems (FMS). A computer in FMS can be used to monitor and control the operation of the whole factory.

Automation has also had an influence on the areas of the economy other than manufacturing.

Many industries are highly automated or use automation technology in some part of their operation. In communications and especially in the telephone industry dialling and transmission are all done automatically. Railways are also controlled by automatic signalling devices, which have sensors that detect carriages passing a particular point. In this way the movement and location of trains can be monitored.

TYPES OF AUTOMATION

         Manufacturing is one of most important application fields for automation technology. There are several types of automation  in manufacturing. The examples of automated systems used in manufacturing are described

1. 1.  Fixed automation, sometimes called «hard automa­tion » refers to automated machines in which the equip­ment configuration allows fixed sequence of proc< operations. These machines are programmed by the design to make only certain processing operations. The, are not easily changed over from one product to another. This form of automation needs high initial investments and high production rates. That is why it is suitable for products that are made in large volumes. Examples of fixed automation are machining transfer lines found in the automobile industry, automatic assembly machines and certain chemical processes.
2. 2.  Programmable automation is a form of automation for producing products in large quantities, ranging from several dozen to several thousand units at a time. For each new product the production equipment must be re- programmed and changed over. This reprogramming and changeover take a period of non-productive time. Pro­duction rates in programmable automation are generally lower than in fixed automation, because the equipment is designed to facilitate product changeover rather than for product specialization. A numerical-control machine- tool is a good example of programmable automation. The programme is coded in computer memory for each dif­ferent product style and the machine-tool is controlled by the computer programme.
3. 3.  Flexible automation is a kind of programmable au­tomation. Programmable automation requires time to reprogram and change over the production equipment for each series of new product. This is lost production time, which is expensive. In flexible automation the num­ber of products is limited so that the changeover of the equipment can be done very quickly and automatically. The reprogramming of the equipment in flexible auto­mation is done at a computer terminal without using the production equipment itself. Flexible automation allows a mixture of different products to be produced one right after another.

 

ROBOTS IN INDUSTRY

Today most robots are used in manufacturing operations. The applications of robots can be divided into three categories:

1. material handling
2. processing operations
3. assembly and inspection.

Material-handling is the transfer of material and loading and unloading of machines. Material-transfer applications require the robot to move materials or work parts from one to another. Many of these tasks are relatively simple: robots pick up parts from one conveyor and place them on another. Other transfer operations are more complex, such as placing parts in an arrangement that can be calculated by the robot. Machine loading and unloading operations utilize a robot to load and unload parts. This requires the robot to be equipped with a gripper that can grasp parts. Usually the gripper must be designed specifically for the particular part geometry.

In processing operations robot manipulates a tool to perform a process on the work part. Examples of such applications include spot welding, continuous arc welding and spray painting. Spot welding of automobile bodies is one the most common applications of industrial robots. The robot positions a spot welder against the automobile panels and frames to join them. Arc welding is a continuous process in which robot moves the welding along the welding seam. Spray painting is the manipulation of a spray-painting gun over the surface of the object to be coated. Other operations in this category include grinding and polishing in which a rotating spindle serves as the robot’s tool.

The third application area of industrial robots is assembly and inspection. The use of robots in assembly is expected to increase because of the high cost of manual labour. But the design of the product is an important aspect of robotic assembly. Assembly methods that are satisfactory for humans are not always suitable for robots, Screws and nuts are widely used for fastening in manual assembly, but the same operations are extremely difficult for one-armed robot.

Inspection is another area of factory operations in h the utilization of robots is growing. In a typical inspection job, the robot positions a sensor with respect e work part and determines whether the part answers the quality specifications. In nearly all industrial robotic applications, the robot provides a substitute for human labour. There are certain characteristics of industrial jobs performed by humans that can be done by robots:

1. the operation is repetitive, involving the same basic work motions every cycle,
2.  the operation is hazardous or uncomfortable for the human worker (for example: spray painting, spot welding, arc welding, and certain machine loading and unloading tasks),

1. the workpiece or tool are too heavy and difficult to handle,

2. the operation allows the robot to be used on two or three shifts.