2. Automated Manufacturing Systems
Manufacturing – the process of producing a
product that meets a specific purpose
Automated Manufacturing Systems – have
computerised controls built into the
manufacturing equipment
Why?
Because many of the processes carried out by a
manufacturing system are repetitive
This makes it ideal for computerised automation
4. Automated Manufacturing Systems
In its most developed form an AMS will control
all aspects of the development of a product,
from it design right through to its dispatch
Most AMS are used for:
Inventory tracking
Record Keeping
Production scheduling
Production control
5. Roles of AMS
Inventory Tracking – recording and checking
that levels of raw materials and components are
sufficient and that the quantity of finished
product will meet demand
Record Keeping – employee records, orders,
sales, supplier’s details, etc
6. Roles of AMS
Production Scheduling – the timing of
production to match customer orders, workers’
time shifts and maintenance periods.
Production Control – controlling the
machinery used to produce the items
7. Common features of AMS
Sharing of data and information
Most AMS rely on sharing of data between the various parts
of the production process
Data from the design stage is commonly used by the
accounting department to perform a cost / benefit analysis
The data produced by the accounting department, along with
the design data, is sent to management for approval
The entire set of data is then sent to the production
department so that they can begin tooling up for the
manufacture of the product
8. Common features of AMS
The ability to collect data from the environment using
sensors. The most commonly used sensors measure:
Temperature
Pressure
Motion
Flow
Light
The data collected from sensors is processed into
information, used by the AMS to complete a task
9. Describing systems
When considering the operation of an AMS it is
useful to revisit some basic concepts related to
systems
A system is a set of component parts (devices
and processes) that accept data and work
together to produce some output
Block diagrams are commonly used in the design
and development of AMS
10. Block Diagrams
INPUT
SYSTEM OUTPUT
System Environment
System boundary
A block diagram of a system
11. Block Diagrams Components
These elements are used to represent system inputs and
outputs
A system can have multiple inputs and outputs
Only half of the circle is labelled as input or output as the
other half of the circle represents inputs to other systems or
outputs from other systems
Rectangles are used to represent the entire
system
Arrows are used to indicate the flow of data /
information
12. Systems and block diagrams
SYSTEM 1 OUTPUT INPUT SYSTEM 2 OUTPUT INPUT SYSTEM 3
The output from one system is often used as the input to another system
13. Systems and block diagrams
SYSTEM 1 OUTPUT INPUT
OUTPUT INPUT
SYSTEM 3
OUTPUT INPUT
SYSTEM 2
OUTPUT INPUT
A system can have several inputs and several outputs
14. Systems and block diagrams
OUTPUT INPUT
OUTPUT INPUT
LARGE SYSTEM
OUTPUT INPUT OUTPUT INPUT
OUTPUT INPUT SUB-SYSTEM 1 SUB-SYSTEM 2
A large system can be broken down into a number of smaller sub systems
15. Common features of AMS
The use of CAD / CAM systems
CAD = Computer Aided Design
CAD systems are used to design the product to the point of
manufacture
CAD provides the designer with precise positioning &
drawing tools to create a variety of images of the product
The most common layout used is the standard drawing layout
However a 3D view of the object can also be created which
can be rotated and viewed from a variety of distances and
directions
16. Common features of AMS
The use of CAD / CAM systems
CAD systems make use of vector graphics which
means that each part of the object design can be
individually viewed and altered
CAM = Computer Aided Manufacturing
CAM systems use the CAD designs to create a series
of instructions and data that can be used by the
computer controlled machinery to create the product
17. Participants and AMS
Supervisors – oversee the operation of the system and
deal with any minor problems that arise
Production planners – adjust system production to
meet the current and emerging needs of customers
Production designers – normally work with the CAD
software to design products
Maintenance Engineers – responsible for the repair
and operating efficiency of the system
18. Reasons for using AMS
Level of automation varies
Repetitive tasks – very boring for human labour. Bored
workers lose concentration and make mistakes more
easily. Automated systems can perform these tasks
efficiently and at high speeds
Faster response time - if the environment changes the
system is able to respond and adapt more readily
resulting in fewer delays
Increased safety – automating dangerous and dirty tasks
reduces the risks to human workers
19. Reasons for using AMS
Better control of production costs – AMS are more
predictable in terms of their operation and have more
consistent operating costs
Better control over the consumption and waste of
material
Better quality control – greater consistency of
production
Greater precision – very precise movements and
actions can be repeated endlessly
20. Reasons for using AMS
Increased productivity – AMS can operate
almost continuously (no sick days, no holidays,
no sleep)
Improved design – the use of information
technology to design and test production items
can save time and money
Balance the above against the social problems
21. Types of AMS
Broadly speaking an AMS may be classified as:
Continuous
Batch
Discrete
22. Continuous AMS
Designed and built for one task (little or no
flexibility). For example, an AMS used to make
sedans cannot be easily altered (if at all) to make
bicycles or sort the mail
The information technology controlling the
AMS is not intelligent
23. Continuous AMS
The inputs and outputs are not expected to
change
Participants require only low level IT skills
The involvement of participants is minimal
Expensive to alter production system or
products
Fast production rate
Suited to the mass production of identical items
24. Batch AMS
Has the capability to switch relatively quickly
between production tasks
Suited to large production runs of limited
duration
Can be quickly re-programmed
Moderate to fast production rate
25. Batch AMS
Increase in the cost and complexity of the
system
More human intervention required in the
control process
Human operators require a greater level of skills
Flow of inputs and outputs occur in batches
26. Discrete AMS
Used to produce items that are not identical or are only
needed in limited quantities e.g. certain scientific
instruments
Automating such a system is very expensive and
complex, making extensive use of artificial intelligence
Human operators usually have a high level of skill and
involvement
Slow production rate
27. Collecting data
Sensors (aka transducers) are devices that measure data
from the environment
This data is often in the form of an electrical voltage
that is digitised and transmitted to a control program
Most AMS rely on real time data to monitor and adjust
the operations of the manufacturing process
Typical sensors include thermometers, light sensors,
flow sensors, motion sensors, pressure sensors
28. Thermometers
Measure the temperature of the air, a fluid or an object
Change in temperature is detected as a result of a change in the
resistance of a conductor
Main types:
Thermistor – uses the change in the resistance in a semi-
conductor as a result of a change in temperature
Resistive temperature detector – uses the change in resistance
of a metal caused by a temperature change
Fibre Optic Thermometer – collects and measures energy
radiated as light
Thermocouple – uses the weak electric current generated
when two different metals in contact with each other are
heated
29. Light Sensors
Detects the presence of light and changes in
light levels
Exploit the photo-electric effect demonstrated
by certain semi-conductors. When light falls on
the semi-conductor an electrical signal is emitted
The quantity of electricity depends on the
strength of the light
30. Light Sensors
Main types:
Phototransistor – uses electricity produced by light striking a
light sensitive semi-conductor
Photoresistor – uses the change in resistance of a semi-
conductor caused by a change in the light level
Charge Couple Device (CCC)– a grid of phototransistors,
used in scanners and cameras
31. Flow sensors
Measures the rate at which liquids and gases travel
through pipes and other channels
Main types:
Turbine – the moving liquid or gas spins a wheel
Hot wire – the moving liquid or gas cools an electrically
heated wire
Pressure difference – the moving liquid or gas is forced
through a constriction which changes its pressure
32. Motion sensors
Main types:
Rotation sensor – measures rotation speed and
direction of a wheel attached to a moving object
e.g. in a ball-type mouse
Timed pulses – uses the time taken for a waveform
( light, sound, radar) to be reflected
Doppler Shift – uses the change frequency of a
reflected waveform
33. Pressure sensors
Main types:
Piezoelectric sensors – use a material that produces a small
electric current when they are deformed (squeezed or
stretched). The strength of the current is proportional to the
force or pressure placed on the material
Capacitance effect sensors – A capacitor is an electronic
device used to store electric charge. By putting pressure on a
capacitor, the shape and size of its stored charge is changed
34. Analogue data to Digital data
Converters (ADC)
PCM – Pulse Code Modulation
Involves taking regular samples of the amplitude
(height) of the analogue signal
The accuracy of the digital signal produced will
depend on the sample rate of the sensor
However, the more samples, the more data that will
require processing and storage
35. Digital data to Analogue data
Converters (DAC)
Amplitude modulation – this involves modifying
the amplitude (height) of the signal in response
to a 1 or 0
Frequency modulation – Uses a higher
frequency for a 1 and a lower frequency for a 0
Phase modulation – changes the phase of a
signal, compared to the standard reference signal
in response to a 1 or a 0
36. Signal Conditioning
This involves the use of electronic filters to
remove noise and improve the quality of data
signals
Noise is unwanted extra signals that are
superimposed on data signals
Noise is caused by power surges, radios,
televisions, etc
37. Damping
In many systems input signals from sensors are
used to control the operation of an output
device
This is known as a feedback loop
In the following diagram a heater has a
controller that uses data obtained from a sensor
38. A typical feedback system
ENVIRONMENT for temperature
INPUT OUTPUT
Temperature
is measured
Temperature
Heater
Sensor
Controller
If the temperature is below a certain level, the heaters are activated, causing
the temperature to rise. If the temperature is above a certain level the heaters
are turned off, causing the temperature to fall.
39. Behaviour of the feedback loop
T
temperature control system
E
M
P
E
R
A
T
U
R
E
TIME
•The temperature is not at a constant level with the graph showing wide
range of temperature swings
•We want to have the temperature settle down so that it reaches a stable
position of 25º C. The problem is deciding how much to vary the heater
control settings as the temperature approaches 25º C
•The process of achieving this stability is called damping
40. Types of Damping
Critically damped system – this gives a quick
response to a change and reaches a new stable position
quickly with little or no instability (this is the preferred
option)
Underdamped system – reacts very quickly to change
but takes some while to settle down to a stable position
Overdamped system – reacts very slowly to a change
and takes some time to reach the new stable output
level
41. Displaying data and AMS
Obviously data is displayed on a monitor or
printout
The final product produced by the AMS can be
consider as displayed data
There are many other devices that display data in
an AMS, such as actuators, electric motors,
stepping motors, relays, hydraulic pumps
42. Actuators
These are mechanical or electro-mechanical devices that are
activated in response to data in the AMS
Solenoids – these are a tightly wound coil of wire surrounding a
magnet
When a current is activated in the coil, the surge of magnetism is
enough to move the inner magnet. This is known as inductance
Switching the current off will create another surge of magnetism
that will reverse the movement of the inner magnet
If this is connected to a valve the valve can be opened or closed
simply by switching the solenoid on or off
43. Electric Motors
Most common control system actuator
Can be used with gears and levers to produce a
variety of movements
Operate in a similar way to solenoids
44. Stepping motors
Electric motors capable of very accurate small
movements
e.g. A hard disk has a stepping motor to
accurately control the position of the read head
over the surface of the disk
45. Relays
Switches that are turned on or off by other electric
currents
Often a very small current is used to turn on a very
large current
Operates using the solenoid principle
A small current in a coil makes enough magnetic force
to move a lever that makes or breaks contact on a
much larger electric current
Transistors are solid state devices that also do the same
thing
46. Hydraulic Pumps
Used to force a liquid (such as oil) into piston
chambers
The pressure created by the pump causes the
piston to move and thus create mechanical
action
Can achieve rapid and precise movements
Often used for robotic arms
