CHAPTER 11 - TYPE OF PROCESSES

PROCESS CONTROL SYSTEM – TYPES OF PROCESS

                

            Type of processes carried out in modern manufacturing industries can be grouped into 3 general areas in term of the kind of operation that takes place:

a.       Continuous process

            Is one in which raw materials enter one end of the system and the finished product comes out the other end of the system.

            The picture shows a continuous process engine assembly line. Engine blocks are fed into one end of the system and completed engines exit at the other hand. In the continuous processes, the product material is subjected to different treatment as it flows through the process (in this case, assembly, adjustment, and inspection). Auto assembly involves the use of automated machines or robots. At each station, parts are supplied as needed.

b.      Batch production

           In batch processing these is no flow of product material from one section of the process to another. Instead, asset amount of each of the input to the processes is received in a batch and then some operation performed on the batch to produce a finished product or an intermediate product that need further processing. Each batch of the product may different.

c.       Individual products production

           The individual product production process is the most common of all processing system. A series of operation produces a useful output product. The item that produced maybe required to be bent, drilled, welded, and so on at different step in the process. The workpiece is normally a discrete part that must be handled on an individual basis.

The control of machines or processes can be divided into the following categories:

·         Electromechanical control

·         Hardwired electronic control

·         Programmable Hardwired electronic control

·         Programmable logic control (PLC)

·         Computer control

Possible control configuration include:

a.       Individual control (is used to control single machine, doesn’t normally required communication with other controller)

b.      Centralized control (is used when several machines or processes are controlled by one central controller. This control layout utilizes a single large control system to control many diverse manufacturing processes and operation. Each individual step in the manufacturing process is handled by a central control system controller. No exchange of controller status or data is sent to other controller)

c.       Distributed control (differs from centralized system in that each machine is handled by a dedicated control system. Each dedicated control is totally independent and could be removed from the overall control scheme if it were not for the manufacturing function perform. Distributive control involved two or more computer communicating with each other to accomplish the complete control task)

References:
Petruzella, Frank. 1996. Industrial Electronics. Mc-Graw Hill. Singapore