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Contents
Contents
Hong Kong IGDS 2000
Industrial Control
Table of Contents
End
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Chapter 0. Introduction
Chapter 0. INTRODUCTION
0.1 AUTOMATE, EMIGRATE, LEGISLATE, OR
EVAPORATE
"Automate, emigrate, legislate or evaporate." This was a choice many manufacturers.
Some manufacturers tried to lower prices by reducing manufacturing costs. They either automated or emigrated.
Many countries legislated trade barriers to keep high quality, low cost products out. Manufacturers who did nothing
... disappeared, often despite their own government's protective trade barriers.
Many consumers still choose imports over domestic products, but some North American manufacturers are now
trying more thoughtful measures to meet the challenge.
Automation is a technique that can be used to reduce costs and/or to improve quality. Automation can increase
manufacturing speed, while reducing cost. Automation can lead to products having consistent quality, perhaps even
consistently good quality. Some manufacturers who automated survived. Others didn't. The ones who survived
were those who used automation to improve quality. It often happened that improving quality led to reduced costs.
0.2 THE ENVIRONMENT FOR AUTOMATION
Automation, the subject of this textbook, is not a magic solution to financial problems. It is, however, a valuable
tool that can be used to improve product quality. Improving product quality, in turn, results in lower costs.
Producing inexpensive, high quality products is a good policy for any company.
But where do you start?
Simply considering an automation program can force an organization to face problems it might not otherwise face:
l What automation and control technology is available?
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Are employees ready and willing to use new technology?
l What technology should we use?
l Should the current manufacturing process be improved before automation?
l Should the product be improved before spending millions of dollars acquiring equipment to build it?
Automating before answering the above questions would be foolish. The following chapters describe the available
technology so that the reader will be prepared to select appropriate automation technology. The answers to the last
two questions above are usually "yes," and this book introduces techniques to improve processes and products, but
each individual organization must find its own improvements.
Chapter 0. Introduction
0.2.1 Automated Manufacturing, an Overview
Automating of individual manufacturing cells should be the second step in a three step evolution to a different
manufacturing environment. These steps are:
1. Simplification of the manufacturing process. If this step is properly managed, the other two steps
might not even be necessary. The "Just In Time" (JIT) manufacturing concept includes procedures
that lead to a simplified manufacturing process.
2. Automation of individual processes. This step, the primary subject of this text, leads to the
existence of "islands of automation" on the plant floor. The learning that an organization does at this
step is valuable. An organization embarking on an automation program should be prepared to accept
some mistakes in the early stage of this phase. The cost of those mistakes is the cost of training
employees.
3. Integration of the islands of automation and other computerized processes into a total
manufacturing and business system. While this text does not discuss the details of integrated
manufacturing, it is discussed in general in this chapter and again. Technical specialists should be
aware of the potential future need to integrate, even while they embark on that first "simplification"
step.
The large, completely automated and integrated environment shown in figure 0.1 is a Computer Integrated
Manufacturing (CIM) operation. The CIM operation includes:
l Computers, including:
i one or more "host" computers
ii several cell controller computers
iii a variety of personal computers
iv Programmable Controllers (PLC)
v
computer controllers built into other equipment
l Manufacturing Equipment, including:
i
robots
ii
numerical control machining equipment (NC, CNC, or DNC)
iii
conntrolled continuous process equipment (e.g., for turning wood pulp into paper)
iv
assorted individual actuators under computer control (e.g., motorized conveyor systems)
v
assorted individual computer-monitored sensors (e.g., conveyor speed sensors)
vi
pre-existing "hard" automation equipment, not properly computer-controllable, but
monitored by retro-fitted sensors
l Computer Peripherals, such as:
i
printers, FAX machines, terminals, paper-tape printers, etc.
Chapter 0. Introduction
l Local Area Networks (LANs) interconnecting computers, manufacturing equipment, and shared
peripherals. "Gateways" may interconnect incompatible LANs and incompatible computers.
l Databases (DB), stored in the memories of several computers, and accessed through a Database
Management System (DBMS)
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Software Packages essential to the running of the computer system. Essential software would include: the
operating system(s) (e.g., UNIX, WINDOWS NT, OS/2 or SNA) at each computer; communications
software (e.g., the programs which allow the LANs to move data from computer to computer and which
allow some controllers to control other controllers); and the database management system (DBMS)
programs
l assorted "processes" which use the computers. These computer- users might include:
i
humans, at computer terminals, typing commands or receiving information
from the computers
ii
Computer Aided Design (CAD) programs
iii
Computer Aided Engineering (CAE) programs
iv
Computer Aided Manufacturing (CAM) programs, including those that do
production scheduling (MRP), process planning (CAPP), and monitoring of
shop floor feedback and control of manufacturing processes (SEC)
v
miscellaneous other programs for uses such as word processing or financial
accounting
As of this writing, very few completely computer integrated manufacturing systems are in use. There are lots of
partially integrated manufacturing systems. Before building large computer integrated systems, we must first
understand the components and what each component contributes to the control of a simple process.
Chapter 0. Introduction
Fig. 0.1 A computer integrated manufacturing environment
0.3 CONTROL OF AUTOMATION/PROCESS CONTROL
Automated processes can be controlled by humans operators, by computers, or by a combination of the two. If a
human operator is available to monitor and control a manufacturing process, open loop control may be acceptable.
If a manufacturing process is automated, then it requires closed loop control.
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