JM506 PROGRAMMABLE LOGIC CONTROLLER

INTRODUCTION TO AUTOMATION SYSTEM

JABATAN KEJURUTERAAN MEKANIKAL

POLITEKNIK UNGKU OMAR

RUSMAY ABDULLAH

Industry

• In a general sense the term “Industry” is definedas follows.

• Definition: Systematic Economic Activity thatcould be related to Manufacture/Service/ Trade.

• In this course, we shall be concerned withManufacturing Industries only.

• a general sense the term “Industry” is defined as shallbe concerned with Manufacturing Industries only.

Automation

• The word ‘Automation’ is derived from Greekwords “Auto” (self) and “Matos” (moving).Automation therefore is the mechanism forsystems that “move by itself”.

• Automation can be defined as a technologyconcerned with the application of mechanical,electronic, and computer-based systems tooperate and control production.

Reasons for Automating

1. To increase labor productivity.

Automating a manufacturing operation usuallyincreases production rate and labor productivity. Thismeans greater output per hour of labor input.

2. To reduce labor cost.

Ever-increasing labor cost has been and continuesto be the trend in the world’s industrialized societies.Consequently, higher investment in automation hasbecome economically justifiable to replace manualoperations. Machines are increasingly beingsubstituted for human labor to reduce unit productcost.

Reasons for Automating

3. To mitigate the effects of labor shortages.

There is a general shortage of labor in manyadvanced nations, and this has stimulated thedevelopment of automated operations as a substitutefor labor.

4. To reduce or eliminate routine manual and clericaltasks.

An argument can be put forth that there is socialvalue in automating operations that are routine,boring, fatiguing, and possibly irksome. Automatingsuch tasks serves a purpose of improving the generallevel of working conditions.

Reasons for Automating

5. To improve worker safety.

By automating a given operation and transferringthe worker from active participation in the process toa supervisory role, the work is made safer. The safetyand physical well-being of the worker has become anational objective with the enactment of the OSHA in1970. This has provided an impetus for automation.

6. To improve product quality.

Automation not only results in higher productionrates than manual operations; it also performs themanufacturing process with greater uniformity andconformity to quality specifications. Reduction offraction defect rate is one of the chief benefits ofautomation.

Reasons for Automating

7. To reduce manufacturing lead time.

Automation helps to reduce the elapsed timebetween customer order and product delivery,providing a competitive advantage to themanufacturer for future orders. By reducingmanufacturing lead time, the manufacturer alsoreduces work-in-process inventory.

8. To accomplish processes that cannot be donemanually.

Certain operations cannot be accomplishedwithout the aid of a machine.

Reasons for Automating

These processes have requirements for precision,miniaturization, or complexity of geometry, thatcannot be achieved manually.

Examples include certain integrated circuit fabricationoperations, rapid prototyping processes based oncomputer graphics (CAD) models, and the machiningof complex, mathematically defined surfaces usingcomputer numerical control. These processes canonly be realized by computer controlled systems.

9. To avoid the high cost of not automating.

There is a significant competitive advantagegained in automating a manufacturing plant.

Reasons for Automating

The advantage cannot easily be demonstrated on acompany’s project authorization form.

The benefits of automation often show up inunexpected and intangible ways, such as in improvedquality, higher sales, better labor relations, and bettercompany image. Companies that do not automateare likely to find themselves at a competitivedisadvantage with their customers, their employees,and the general public.

Classification Of Automation:

A. Fixed automationB. Programmable automationC. Flexible automation

A. FIXED AUTOMATION

This control system is designed to perform a

specific task

Functions of control circuit is fixed and permanent.

It will be complicated if we want to do other task

apart from the existing task

Examples:

Mechanized assembly lines.

Mechanical lines.

A. FIXED AUTOMATION

Example : Fixed Automation

Assembly lines Mechanical lines

Characteristics:

Justified/used where production rates/volumes are

high.

High initial investment for custom engineered

equipment

Normally cannot accommodate product changes.

Depend largely on skill to organize the operations.

Produces large numbers of nearly identical parts

Product design must be stable over its life

A. FIXED AUTOMATION

the production equipment is designed with the capability to

change the sequence of operations to accommodate

different product configurations.

The operation sequence is controlled by a program which is a

set of instructions coded so that they can be read and

interpreted by the system.

New programs can be prepared and entered in to the

equipment to produce new products.

Examples:

Numerically controlled (NC) machines.

Industrial robots

B. PROGRAMMABLE AUTOMATION:

Example : Programmable Automation

B. PROGRAMMABLE AUTOMATION:

Characteristics:

Sequence controlled by a program

High investment in general purpose equipment

Lower production rates

Flexibility to deal with variation

Suitable for batch production

Smaller volumes (than fixed) of many different parts

More flexible than fixed automation

Major disadvantage: setup prior to each new part

Large batch size (due to setups)

Speed sacrificed for flexibility

B. PROGRAMMABLE AUTOMATION:

A flexible system consists of a group of processing

stations (CNC), interconnected by means of an

automated material handling and storage system, and

controlled by an integrated computer system.

Examples:

Use of pallet fixtures for holding parts.

Flexible manufacturing systems (FMS)

Automated Guided Vehicles (AGV) for material

handling

C. FLEXIBLE AUTOMATION:

Example : Flexible Automation

FMS

AGV

C. FLEXIBLE AUTOMATION:

Characteristics:

It is extension of programmable automation

No time lost for change over

High investment in custom-engineered systems

Production of product mix

Flexibility to deal with design variations

Low to medium quantities

Compromise between fixed and programmable automation in speed and flexibility

C. FLEXIBLE AUTOMATION:

COMPARE THE TYPES OF AUTOMATION

The main advantages of automation are:

1. Replacing human operators in tasks that involve

hard physical work.

2. Replacing humans in tasks done in dangerous

environments (i.e. fire, space, volcanoes, nuclear

facilities, underwater, etc.)

3. Performing tasks that are beyond human

capabilities of size, weight, speed, endurance, etc.

ADVANTAGES AND DISADVANTAGES OF

AUTOMATION CONTROL IN INDUSTRY

4. Economy improvement: Automation may improve

in economy of enterprises, society or most of

humanity. For example, when an enterprise invests

in automation, technology recovers its investment;

or when a state or country increases its income

due to automation like Germany or Japan in the

20th Century.

5. Reduces operation time and work handling time

significantly.

The main disadvantages of automation are:

1. Unemployment rate increases due to machines

replacing humans and putting those humans out

of their jobs.

2. Technical Limitation: Current technology is unable

to automate all the desired tasks.

3. Security Threats/Vulnerability: An automated

system may have limited level of intelligence,

hence it is most likely susceptible to commit error.

4. Unpredictable development costs: The research

and development cost of automating a process

may exceed the cost saved by the automation

itself.

5. High initial cost: The automation of a new product

or plant requires a huge initial investment in

comparison with the unit cost of the product,

although the cost of automation is spread in

many product batches of things.

There are five (5) of the control system based on

supply. These systems are as follows:

I. Electric Control System

II. Pneumatic Control System

III. Hydraulic Control System

IV. Electro-Pneumatic Control System

V. Electro- Hydraulic Control System

CONTROL SYSTEM BASED ON SUPPLY

I. ELECTRIC CONTROL SYSTEM

System can be controlled manually and automatically.

Manual Electric Control System

Automatic Electric Control System

Pneumatic control system is a system that uses compressed air to produce power/energy to perform any task.

Pneumatic systems found in many industrial systems such as food industry, petrochemical and industrial involves robotics.

Pneumatic systems requires: Compressed air supply Control valve Connecting tube Transducer

II. PNEUMATIC CONTROL SYSTEM

Basic circuit design for single cylinder:

II. PNEUMATIC CONTROL SYSTEM

Indirect MethodDirect Method

Hydraulic control system is a system that uses fluid to generate power/energy.

The hydraulic system used in the automobile industry such as power systems, braking systems, cranes, car jack, satellite and others.

The fluid used is oil. The hydraulic system requires: Hydraulic fluid supply Control Valve Cylinder

III. HYDRAULIC CONTROL SYSTEM

Basic hydraulic circuit system:

III. HYDRAULIC CONTROL SYSTEM

The primary levels of an electro-pneumatic system structure are:

Energy supply (compressed air and electricity)

Input elements (limit switches / pushbuttons / proximity sensors)

Processing elements (switching logic, solenoid valves, pneumatic to electric converters)

Actuators and final control elements (cylinders, motors, directional control valves, indicators)

IV. ELECTRO-PNEUMATIC CONTROL SYSTEM

Electro-pneumatic circuit diagram

IV. ELECTRO-PNEUMATIC CONTROL SYSTEM

The primary levels of an electro-pneumatic system structure are:

Energy supply (hydraulic motor and electricity)

Input elements (limit switches / pushbuttons / proximity sensors)

Processing elements (switching logic, solenoid valves)

Actuators and final control elements (cylinders, motors, directional control valves, indicators)

IV. ELECTRO-HYDRAULIC CONTROL SYSTEM

Schematic diagram of the electro-hydraulic position control system.

IV. ELECTRO-HYDRAULIC CONTROL SYSTEM

Relays• A relay is a switch that is turned on or off using electricity.

• Relays allow a low-power signal to control a large amount

of power.

• Most relays work by energizing a small electromagnet which

causes the contacts of a switch to close, as shown below.

• Passing a small current through the coil causes the iron core to

become magnetized; the magnetized iron core attracts an iron

mass attached to the moveable contacts, causing the contacts to

close.

• Relays are designed so that a SMALL current flowing through the

coil leads switches a LARGER current through the contact leads.

• There are many different types of relays (not all use

electromagnets).

Types of Relays

Single Pole – relay have 1 common

Double Pole – relay have 2 common

Single Throw – relay have NC or NO

Double Throw – relay have NC and NO

Relay Building Diagram

A simple electromagnetic relay consists of a coil of

wire wrapped around a soft iron core,

an iron yoke which

provides a low

reluctance path for

magnetic flux, a

movable iron

armature, and one or

more sets of contacts.

CONTACTORS

• A contactor is used to control an electric load in a control systems.

• Contactors make or break a set of contacts that control the voltage applied to some load in cooling systems.

How the contactor works

• When current passes through the electromagnet, a magnetic

field is produced, which attracts the moving core of the

contactor.• The electromagnet coil draws

more current initially, until its

inductance increases when the

metal core enters the coil. The

moving contact is propelled by

the moving core; the force

developed by the

electromagnet holds the

moving and fixed contacts

together.

• When the contactor coil is de-

energized, gravity or a spring

returns the electromagnet core

to its initial position and opens

the contacts.

MOTOR STARTER.

Main Contact.

• Main contact of the contactor are normally open

contact and usually use to connect power load to the

main supply.

Auxiliary Contacts

• Auxiliary contacts are secondary switching devices

which work in conjunction with primary switching

equipment such as circuit breakers, relays, and

contactors. These contacts are physically linked to the

main switching mechanism and activate at the same

time it does.

Examples of contactor use in motor control system

Relay vs Contactor

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