Automated Manufacturing Systems

Characteristics of automated manufacturing systemsIdentify and describe the features of automated manufacturing systems:

Automated manufacturing systems as information systems involved in production, by inventory tracking, record keeping, production scheduling and actual production

o Inventory control and tracking: This includes all items needed for production being counted and stored, and orders placed automatically when minimum numbers of any item are reached.

o Example: Tip Top Bakeries Inventory tracking is very important for Tip Top Bakeries because it allows them to keep track of how much bread they have and how much has gone out to shops. If the number goes below a certain level, it tells the system to produce more bread. Without this inventory tracking, two scenarios could occur. There may be an increase in demand for bread and the company may not produce more bread to keep up with this demand, and run out of bread, which causes production delays and financial losses. Without inventory tracking, the demand for bread could decrease for a few days, and the company would not realise, continue producing bread at the same rate and have an oversupply of bread which can go past its use-by date and be unable to be sold. Inventory tracking allows a company to be accustomed to peak and off-peak seasons and adjust with their stock levels. Inventory tracking also helps the company keep track of each component that goes into bread so they have sufficient levels of each component to actually produce the loaves of bread. If inventory tracking doesn’t occur and they run out of at least one of these components, they will be unable to produce bread, production will come to a stop, and there will be financial losses. For example, ordering not enough wheat means no bread being made. On the other hand, though, ordering too much wheat leaves no room for other products to be stored and also presents a fire hazard. It also ensures that the right level of each component goes into each loaf of bread. It also allows the company to keep track of different kinds of bread.

o Record-keeping: This includes all information about who did what work, when they did it, and how well they did it. It can also cover ordering procedures and all production steps, producing invoices and making delivery arrangements.

o Production scheduling and actual production: Automated manufacturing systems have built-in computerised controls that schedule and perform every part of production automatically e.g. automatic movement of material, precise scheduling and execution of all work steps and automatic monitoring of quality and safety.

The direct users of these systems aso Supervisors overseeing operation

They are in control of the system and ensure that the production does not get behind schedule.

Extraordinary conditions or sudden changes are better handled by the creativity and skills of experienced humans.

Describe how they interact with the information technology in the system: They oversee all the information technology in a certain area and

ensure that it runs smoothly, for example, the assembly department.

o People whose task is dependent on the system for information Information may include:

Number of parts needed for a product Number of employees and skills needed to produce a product Cost of parts Cost of production Sources of component parts Prediction of market need Time required to machine or process parts Number of finished machines in stock

Describe how they interact with the information technology in the system:They have a certain task that relies on the system’s information output. They work with a certain machine, for example, a drill press.

The ability of these systems to collect data from the environment through a wide range of sensors, process this data into information and use this information to complete a physical taskAMS are able to collect data from the environment by using a range of sensors to detect changes in temperature, pressure, position and so on which is then processed in the controller. The controller converts and often amplifies this input data and processes it to give information that is sent as signals to actuators, which complete some physical task as a result.

o Sensors are collection devices used to measure environmental factors. Thermostats sensing temperature in an air conditioner or a motion detector detecting movement and opening a door are examples of sensors. They input data that must then be processed.

A passive infra-red sensor detects movement by sensing temperature (heat radiation) contrast between an intruder moving through the detection pattern and the background environment.

A microwave sensor detects walking, running, or crawling human targets by generating an electromagnetic field between the transmitter and the receiver creating an invisible detection zone. When an intruder enters the zone, the field is changed.

A photoelectric sensor has a photoelectric beam. If this beam is broken, then it means someone disturbed it.

o Processing data into information is done using a microprocessor as a controller. These regulate the operation of the system, allowing computer control of input data from sensors, processing of this data, and signals being sent out to actuators to make changes to the manufacturing process. They receive data from a sensor and

change it into information that can be used by a system. For example, a sensor often collects analog data and this needs to be converted to digital.

o Using this information to complete a physical task tends to require moving the product from one location to another during a series of processing steps. Actuators are output devices and perform functions as a result of signals from the controller, stopping a pump, moving a switch or turning on a light beam. Some common actuators are electric motors, solenoids and stepping motors.

The use of microprocessors in these systems as the controllero Microprocessors are silicon chips that perform processing in computers. In AMS,

they allow computer control of input data from sensors, and process this data before sending out signals to actuators.

Block diagrams as a tool for describing the interactions between information technology items within these systems(Represent the information technology within an AMS)

Examples of automated manufacturing systems Specific examples, including:

o Assembly line production such as the car industry An arrangement of machines, equipment and workers to allow for the

continuous flow of components for mass production. Material movement is designed to be short and simple with no cross-flow or backtracking.

Participants: The warehouse and assembly line workers, IT staff and so on, who use the information technology incorporating the robotic and computer hardware and the CAM software.

Data/Information: Raw materials enter at one end, proceed through each workstation, and emerge at the other end as a completed product. Information needs to be kept about production times, machine maintenance, faults in production and total number of products produced over a set period. Cars, for example, need to be labelled and packed for various destinations both interstate and internationally

Information Technology: Conveyor, robots, self-regulating equipment, Separate parts that need to be assembled together

Relationship between Participants, Data/Information and Information Technology: The warehouse and assembly line workers produce the completed product from the raw materials at the beginning and log information on production times and total number of products produced over a set period. Machine repairmen record machine maintenance, faults in production. IT staff maintain the online copy of all this information and ensure a backup is regularly made so little data is lost.

Reasons for automation: Safety levels Maintaining good quality control Reducing the cost of production Removal of repetitive tasks for human workers

Diagrammatical representation of the processing steps:

o Materials and production line scheduling Production line attributes such as start and stop times, line speed, line

capacity and lead time. This lets you specify the production line where you build each assembly and the line speed determines the production run rate to schedule that assembly on the line.

Participants: Workers on the production line, IT staff who work information technology, supervisor who sets production schedules.

Data/Information: Production line, line speed, production run rate, start and stop times, line capacity, lead time.

Information Technology: Software to record and organise the scheduling Relationship between Participants, Data/Information and Information

Technology Reasons for automation:

Cost reduction Precision control Greater efficiency

Diagrammatical representation of the processing steps: o Automated warehouses

These use robotic devices to receive, count, move, barcode, store and collect components in a warehouse situation. Each storage location must be programmed, as well as each discrete item type, either by a barcode or similar identification method. The program must also avoid collisions of robotic devices by selecting pathways that do not put two devices at the same crossing at the same time. The tracking of warehouse items is also important for:

Knowing when to reorder a part Monitoring the daily or weekly use of a part Knowing which products are selling or not Calculating capital tied up in warehouse stock Being able to assemble customer orders from warehouse stock

Knowing what space is available for new product storage. Participants: Include warehouses workers and IT staff who use the

information technology incorporating the robotic and computer hardware and software programs.

Data/Information: Barcodes that identify a product’s location, item type, everything about it which is stored in a database

Information Technology: Robots, computers to program movement of devices

Relationship between Participants, Data/Information and Information Technology

Reasons for automation: Better utilisation of warehouse space Safety Productivity gains Resultant cost reductions

Diagrammatical representation of the processing steps:

o CAD/CAM such as: computing numerical control (CNC) systems CAD is the use of information technology to design and analyse a product or

object. Designers working with a CAD system, rather than on a traditional drafting board, create the lines and surfaces that form the object and store this model in the database. It allows the designer to perform various analyses such as heat transfer calculations. The design is refined by adjustment made on the basis of these analyses. The CAD system then generates the detailed drawings required to make the product.

CAM is the specialised information technology tools that automate the entire manufacturing system. It controls the actions of the plant equipment and monitors the collection of data from the factory, the analysis of the data and the communication of the results to management.

A CAD/CAM system involves automation of manufacturing operations and elements in the entire design and manufacturing procedure. It has been applied in machined components, electronics and equipment design.

Numerical control is a form of programmable automation in which numbers control a machine. It allows complex parts to be fabricated quickly and accurately by automated machine tools that directly grind, mill etc. the raw material to the finished product. CNC is where a microprocessor is programmed to control some or all of these functions.

Participants: Supervisors, managers, office staff Data/Information: Coordinates in three dimensions defining the exact

position of tools, analysis, data from the factory, feedback ensuring the program has been correctly performed.

Information Technology: Numerical control machines, Database, Tools to perform analyses and generate detailed drawings

Relationship between Participants, Data/Information and Information Technology: Supervisors at the planning, design or manufacturing stages can access all details through the computerised system. The users of the system include managers, office staff and so on.

Reasons for automation: One person can operate more than two machine tools Greater accuracy with better repeatability The ability to process products that have complex shapes Shorter processing time

Diagrammatical representation of the processing steps: o Rapid prototyping

Techniques to quickly fabricate a scale model of a part or assembly using three-dimensional computer aided design (CAD) data. It can be used for visualisation, testing and models.

Basic methodology is: A CAD model is constructed then converted to STL format. The

resolution can be set to minimise stair stepping The RP machine processes the .STL file by creating slice layers of the

model The first layer of the physical model is created. The model is then

lowered by the thickness of the next layer, and the process is repeated until completion of the model.

The model and any supports are moved. The surface of the model is then finished and cleaned.

Participants: IT staff who maintain the information technology, designers and workers who use the rapid prototyping system

Data/Information: Size and other aspects of a model are fed into rapid prototyping which produce a scaled model

Information Technology: Rapid prototyping machine, lasers, CAD Relationship between Participants, Data/Information and Information

Technology

Reasons for automation: Increase effective communication Decrease development time by allowing corrections to a product to

be made early in the process. Decrease costly mistakes Extend product life by adding necessary features and eliminating

redundant features early in the design Diagrammatical representation of the processing steps:

o Mail sorting The collection, sorting and delivery of mail to various homes and businesses,

now generally performed by scanning devices using barcode readers or OCR software to automatically ‘read’ the postcodes, thus sorting the letters into areas and suburbs. Those without postcodes or illegible ones require human inspection and handling.

Participants: Sorting and loading workers, IT staff who use the information technology incorporating the robotic hardware and the scanning software

Data/Information: City/town of delivery, changed addresses, accounting information

Information Technology: Scanning devices using barcode readers or OCR software

Relationship between Participants, Data/Information and Information Technology: The sorting and loading workers send the mail to houses and businesses. Postcodes that the system cannot read are read by the sorting workers who handle it themselves. IT staff maintain the technology.

Reasons for automation: Faster decision making Productivity gains Cost reduction

Diagrammatical representation of the processing steps:

Reasons for automation, including:

o Repetitive tasks Repetitive work, when performed continuously by human labour, can be

very boring. Automated manufacturing systems can perform these tasks continuously and at high speed. Bored workers easily lose concentration and will make mistakes more easily. For example, in the automobile industry, automation allows uniformity and quality on all cars, especially as the machines can be run for long hours at little cost i.e. productivity gains. Humans continuously putting bottle caps on bottles in a factory will get bored and make mistakes.

o Faster decision-making The software used in CAD, for example, allows the user to make a virtual

model which can simulate things a product may need in certain situations. A computer tends to make decisions faster. For example, in a Coke factory

where the level of Coke in the bottle is measured. It is a lot faster to use automation with light sensors etc. as opposed to a person manually doing this. There are also fewer delays.

o Safety Reduced safety hazards for humans because machines now perform the

dangerous tasks. For example, spray painting a car. Hazardous due to noxious fumes.

o Cost reduction Machines are cheaper to run over a period of time, because it is possible to

run them for many hours at little cost. They are also more predictable in their operations and have more consistent operating costs, as well as providing far better control over the consumption and waste of materials.

o Customisation Customers can customise their products, for example, with some cars. They

can choose the seat colour, steering wheel colour etc. This is easily done using simulation and modelling, as CAD allows faster and more accurate designing of products, often increasing the efficient use of raw materials.

o Quality control Self-sensing machines maintain consistency and accuracy. For example, in

cars, using machines that do not tire on the production line allows uniform quality. Humans are different.

However, with machines, a small mistake in the design in the first place means that every single product will have that mistake and need to be recalled.

o Precision and acceptable tolerance range Sensing, self-regulating machinery keep themselves working accurately. Humans have a wider margin for error. Machines have a much small margin

for error, so are capable of controlling very precise movements and actions that can be repeated endlessly.

o Productivity gains

Machines produce products more quickly and can have much longer working hours. They do not need rest, meal breaks, annual holidays or (ignoring system maintenance time) sick leave.

o Gains through simulating and modelling, such as: Automated structural calculations

Where the models are built into the software allow for component strengths and ratios to be calculated automatically and for a range of materials. Engineers often use it to determine how to best construct something with the minimum cost.

Automated ordering of components Where lower limits are set on component numbers and when these

are exceeded, that component is ordered automatically to restore the minimum number.

Collecting in automated manufacturing systems Systems that collect data and information from participants via computer aided design

(CAD) software and directly link this to the rest of the system through computer aided manufacture (CAM)(Discuss the relationship between CAD and CAM in manufacturing systems)

o Computer Aided Design (CAD) involves the use of computer hardware and graphics software to generate design drawings. Modern CAD equipment enables the designer to quickly produce very accurate and realistic images of products to be manufactured. Computer Aided Manufacturing (CAM) is a system of automatically producing finished products by using computer controlled production machines. CAD and CAM work together in that the digital model generated in CAD is inputted to the CAM software package. The CAM software needs to know the physical shape of the product (CAD model) before it can compose a proper set of fabrication instructions to a production machine. This relationship can enable the automation of the entire manufacturing process.

Identification of the data to be collected and the most appropriate input device(identify data required by a manufacturing system and recommend the most appropriate device to collect data for a given scenario)

o Identifying the types and forms of data to be collected is a critical element when planning the most appropriate input device for an automated system. If the automated system is to replace a manual or only partly automated one, then the human workers and their supervisors are often the best source of useful information about the strengths and weaknesses of existing systems and the requirements of the proposed one.

o Text and numbers form the most common data inputs for the information systems used in manufacturing. A wide range of input devices supply numerical data to an information system. Text-based data will usually be entered by the system operators and other participants, for example, manually programming a CNC lathe. Audio, image and video can also be supplied as data inputs but usually require a great deal of processing to be useful.

For example, if you were making mail sorting at a post office automated: The data that is collected includes the postcodes, names etc. Therefore, the most appropriate input device for mail sorting would be generally scanning devices, such as barcode readers or OCR software to automatically ‘read’ the postcodes.

Another example would be a conveyor belt. Data identifying the items passing along a conveyor belt could be collected by a video camera and

entered as video data. The system would then have to analyse the video images to identify each item. This would require the use of shape or pattern recognition software to identify the items. The cost of such a system, especially with reliable and quick processing, would be quite high. Alternatively, barcodes could be attached to each item before it is placed onto the conveyor belt. Inexpensive barcode readers could be used to scan each item as it passes along the belt. The numerical data from the scanners could be sent directly to the information system without the need for any additional processing. The table below is a summary of the types of data that would be needed by an automated manufacturing system:

Describe the physical operation and scientific principle(s) underlying sensors used to collect data, including:

o Temperature Thermostats are switches that respond and remain open until a certain

adjustable temperature threshold, upon which the switches close. It can be used to turn mains electrical power on and off when the temperature moves beyond the set level. Refrigerators and stoves are examples.

Thermistors are resistors that use the change in resistance of a semiconductor to measure temperature with a metallic conductor such as copper, nickel or platinum that has a changing resistance in response to temperature change, with the resistance dropping lower as the temperature increases. They need to be connected to electronic circuitry to enable devices to be turned on and off, in response to temperature changes. Advantages include:

Operates over a wide range of temperatures Very accurate High sensitivity Fast response

Disadvantages of a thermistor include: Needs a microprocessor to convert the current to a temperature

value Needs electric power

Thermocouples measure temperature using two different metals in electrical contact which, when subjected to heat, generate a small electric voltage in proportion to the heat increase. The size of the current depends on the amount of heat received. Advantages include:

Does not need electric power Disadvantages of a thermocouple include:

Very weak signal which must be amplified Low sensitivity and slow response (Most will not detect changes of

less than 10 degrees Celsius)

Semiconductors are silicon chips that improve their electrical conductivity as the temperature increases. They are used in devices such as DVD players.

Resistive temperature detectors use the change in resistance of a metal caused by a temperature change. A small change in the temperature of the wire will produce a small change in the current flowing through it. Advantages include:

Operates over a wide range of temperatures Current can be easily converted to a temperature value

Disadvantages of resistive temperature detectors include: Not as sensitive as thermistor Needs electric power

A fibre optic thermometer collects the infrared and light energy radiated by an object and sends it down an optical fibre to a detector. They use an optical concentrator to collect and concentrate the energy. The detector measures the energy level and converts it to a temperature value. This type of sensor is ideal for environments where electric current cannot be used, for example in flammable environments. Advantages include:

Operates over a wide range of temperatures Optical fibre collector does not need electric power Fast response

Disadvantages of fibre optic thermometers include: Needs a microprocessor to convert the energy reading to a

temperature value Expensive

Temperature sensors are used in air-conditioners, cars, industrial ovens and refrigerators.

o Pressure Pressure sensors measure the exertion of a force in gases, liquids or solids.

A manometer uses a U-shaped tube to detect gas pressure differences between points 1 and 2, indicated by the movement of the level in tube 2 being registered as a small current the ends of the wires.

Diaphragms are based on an elastic component which alters its shape as the pressure pushing on it alters. As the pressure increases the diaphragm is deformed more and the electric signal increases.

Piezoelectric crystals use a crystal of quartz or another mineral positioned between two plates to produce an electric current when deformed by pressure. The greater the pressure, the larger the current.

Strain gauges operate via a thin metal strip being deformed by pressure and altering its electrical resistance as a result.

o Motion Motion sensors detect changes in position and distances as well as in

velocity and acceleration. They calculate how far an object has moved from its starting position. They use electromagnetic induction to produce a

voltage proportional to the velocity of the conductor moving in a magnetic field. The device consists of an armature with fixed magnets around it like an electric motor. Rotation of the armature produces an induced current in the windings and a voltage proportional to the rate at which the conductor is being rotated.

An accelerometer operates on the effect of inertia of the object to produce a measurable force. This can be achieved by using a strain gauge to detect the change in velocity or acceleration.

o Flow Flow sensors detect the motion of liquids and gases, often the flow of fluids

through pipes and drains. One method of detecting a flow of liquid is to have the liquid turn a small paddle wheel just like an old water wheel. The speed with which the wheel turns gives a measure of the flow of the liquid. The wheel is attached to a tachometer (a resistor curved around into a circle) and the voltage generated by the tachometer is proportional to the flow of liquid.

o Light Light sensors detect the presence of light and changes in the level of light.

They are used in industrial processes to detect imperfections in products. For example, in steel milling, light sensors detect irregularities in the rolled steel as it passes along the rolling mills. Light sensors are also used to control the motion of robots and their interpretation of the environment.

Many light sensors are built around semiconductor materials that will produce electricity when hit by light – the ‘photoelectric effect’. This material is used in solar panels on spacecraft and in other devices to produce electricity directly from sunlight. The quantity of electricity produced depends on the strength or intensity of the light.

A phototransistor uses the photoelectric effect to create a light-sensitive switch. When the phototransistor is exposed to light, it will switch on and allow an electric current to flow through it. The size of the current flowing through the device can be used to measure the strength of the light. Phototransistors are used in floppy disk drives to detect the position of the write-protect switch on the disk. Opening the switch lets light pass through to a phototransistor. This switches on a circuit that prevents the drive from saving or altering data on the disk. Advantages include:

Can be used as a light-sensitive switch Can detect colours and very low light levels High accuracy Fast response

A photoresistor works in a similar way to a thermistor (see above). Its resistance and how much current it will let through depends on the light level. Advantages include:

Inexpensive Fast response

Disadvantages of a photoresistor include:

Not as accurate or as sensitive as phototransistors A charge-coupled device (CCD) is a grid of phototransistors on an integrated

circuit chip where each photoresistor represents an individual pixel. CCDs were originally developed for use in astronomy where they have largely replaced film as the most common method of recording images. CCDs are now widely used in digital still and video cameras. Advantages include:

Can be used as a light-sensitive switch Can detect colours and very low light levels High accuracy Fast response Able to create still images and frames for video

Disadvantages of a CCD include: Expensive

The integration of sensors into manufacturing machinery to automate processing, such as:o Robotic arms

For example, a robot arm with touch sensors in the grippers can pick up and rotate a product.

o Conveyor belts A conveyor belt moves the product down a line (or series of them) and at

certain positions the product is detected by sensors. For example, optical proximity or strain gauge sensors on or around the conveyor belt locate the product. The conveyor belt is stopped and parts are added, filled etc. usually by workers. Between each action the conveyor is restarted and manufacturing continues until the product is completed.

Barcode readers, radio frequency identification tags (RFID) and inventory tracking and production. Describe the operation of barcode readers and RFID tags and how they can assist in inventory tracking and production.

o Barcode readers use a type of photoelectric cell to detect the presence of light or dark lines. As an input device for collecting data, these are much faster and more accurate than a person is at entering a numerical and/or letter code via a keyboard.

o Each product has its own unique identifying number, termed the Universal Product Code, which is scanned by a light reflected from the barcode being detected by the photoelectric cell in the reader. This code identifies the product so that counting in or out can be completed automatically by the computer software.

o Inventory control and tracking is automated with incoming and outgoing products tallied immediately. Predetermined levels allow for automatic restocking and reordering of new supplies whenever required. The locations of all components in a manufacturing process may be tracked by scanning the barcodes as a product passes certain stations in the process. Examples include:

Stock control and pricing of grocery items in supermarkets International courier companies can track and report on the progress of

packages all over the world Marathon runners can be identified as they pass checkpoints

o Advantages include:

Simplicity and ease of use with many modern systems and scanners providing wireless remote data capture

Low cost High accuracy rates at high speeds in comparison to human operators

o Disadvantages include: Requires direct line-of-sight when scanning barcode High error rates Difficult and impractical in many industrial environments because it needs to

be scanned up close Require operators to perform the scan which can lead to human mistakes Only store a small amount of information, typically around 20 characters

o The purpose of a radio frequency identification device is to enable data to be transmitted by a portable tag which can be read by an RFID reader and processed.

o The RFID system consists of a tag, a reader and computer to process the data. RFID readers use a radio frequency to receive radio waves emitted from the tag. A typical RFID tag consists of a microchip attached to an antenna.

o Radio frequency identifier tags (RFID) may be either passive (like the ID chips put in dogs and cats) or active (those with a power source) and work as a transponder. This allows an RFID tag to be attached or incorporated into a product so that the radio waves emitted by the tag can be used to identify them by their unique frequency as they pass a receiver (for up to several metres). They are good for real-time inventory tracking and management within a manufacturing business, though not presently used much once the product leaves the factory (for purposes such as delivery tracking and so on).

o Passive RFIDs are used on pets as ID cards which are read to determine the owner of the cat. They are also used at electronic toll booths, where the systems pick up the E-Tag’s details, which is the RFID.

o Active RFIDs can be used on great white sharks, for example, to keep track of wildlife. They are also used within manufacturing factories for asset tracking.

o Advantages include: Does not require line-of-sight when reading RFID tags Can communicate to tags quickly and scan multiple at once Helps automate the supply chain leading to labour reduction Can keep much information

o Disadvantages: High costs Some users have reported higher error rates than barcodes

The analog nature of the data collected by the sensors and its conversion to digital for use in the system and Describe the process of converting from analog to digital data and demonstrate this with available information technology.

o An ADC takes an analog signal, such as a voltage or electric current, and electronically converts it into digital data. The digital data comprises a number of bits, such as 8, 16, 32 or 64. (The more bits, the more expensive the ADC is)

o For example, a temperature sensor might measure a range of temperatures from 0 to 100 degrees using a voltage range from 0 to 5 volts. An ADC would then change this value into a value range from 0 to 250. For example, a reading of 40 degrees would become 2 volts, which would become converted to a decimal number of 100 or a binary number of 01100100

Damping as the process that modifies the signal to the output device based on the input signal

o Damping is a decrease caused in the amplitude of successive oscillations or waves. Signals are received from a sensor, the controller changes these signals into information, and the actuator carries out the same action.

Types of damping, including:o Underdamping – a quick response to change leading to rapid fluctuations

Occurs if the change is too fast, and the actuator overshoots the desired level. Underdamping causes a return movement that leads the actuator to undershoot the desired level. The actuator continues to fluctuate until stability is reached.

o Overdamping – a slow response to change without fluctuations Occurs if the change is too slow, and the actuator takes longer to reach the

desired level or position. It is a slow reaction to change and return to stability.

o Critical damping – a quick response to change and quick return to stability The preferred rate of change.

o Example situation: A screen door closer can be adjusted to pull the door shut at a certain rate.

Overdamped: The door closes very slowly and flies enter the house. Underdamped: The door closes too quickly and hits the house

owner on the heel every time they enter the house. Critically damped: The door closes at just the right rate to keep out

most flies without hitting people’s heels.

Describe a situation where changes in collected data lead to a requirement for damping.

o Damping is the process of adjusting the stability of the automated system. The controller program is designed to respond to the sensor input and to adapt the output to the actuator quickly. This is known as feedback. Though this is designed to help the system operate at peak efficiency, too rapid feedback can cause the system output to fluctuate wildly if a sudden change occurs. Similarly, if the controller is too slow at making changes to the output, the system takes too long to return to correct operations.

Justify the type of damping for a given situation.o You would usually use critical damping for any given situation, because it has the

preferred rate of change with few fluctuations.

Other processes in manufacturing systems Processing:

o The trend to mass-production while meeting the needs of the individuals Mass production is the manufacture of products in large quantities by

standardised mechanical processes, based on four main principles: Dividing production into relatively simple and highly repetitive

specialised tasks Standardising parts, such as dimensional tolerances, to allow them

to be readily fitted to other parts without adjustment Minimising human effort and maximising output by having

specialised machines, materials and processes Achieving the best balance between human effort and machinery

through the systematic planning of the whole production process Mass production has led to lower costs and major improvements in

uniformity and quality. Large volumes and standardisation have allowed statistical control and inspection techniques to monitor production and control quality.

The major problem is inflexibility. By achieving maximum efficiency in a system through specialised tools and standardised parts, it makes it expensive to redesign a product, as the new design may make old equipment obsolete. By incorporating some flexibility in new systems, organisations reduce the cost of redesigning them later.

o Identify manufacturing systems that quickly adapt to a particular need yet still mass produce, such as a car manufacturing plant that mass produces cars but in the colours required by the customers

A car manufacturing plant mass produces cars but in the colours required by the customer.

A food cannery can produce large quantities of a particular product (e.g. canned fruit), but can be altered to produce new or alternative products.

o The different types of systems, including: Continuous

Features:

o The equipment has to be specially designed for the industry and its product i.e. it is not designed with flexibility in mind. Their highly specialised nature makes them relatively cheap to build and run but expensive and difficult to change.

o Continuous systems are ideal for automated manufacturing because the major production processes are fixed and unlikely to change. The control systems do not require a high degree of intelligence as the inputs and outputs are not expected change, and much of the control software can be built in permanently. Humans do not control much of the system besides turning it on and maintaining it.

Types of tasks they perform: o Chemical manufacturingo Food productiono Oil refining, iron oreo Power generation in power stations and electronic security

systems Scheduling of tasks:

o Operate non-stop for weeks or months, with specific times set aside for maintenance and fine-tuning.

Batch Features:

o Separate production runs, with the system being modified in-between to perform different but similar functions. They are often modular in design for easy reorganisation of components for the following batch. Batch systems need to be much more flexible than continuous systems because they need to be able to be quickly altered to produce new or alternative products. There is a greater degree of human involvement than continuous, as human operators will need to switch the assembly line between production tasks etc.

Types of tasks they perform: o In a car manufacturing plant, sedans may be produced for

one month, then the system is reconfigured and station wagons are produced for the next month

o In a canning or bottling factory, separate production runs are needed for different types of fruit, or drink flavours.

Scheduling of tasks: o There are clear start and end points, with each batch being

produced for a set period of time. Discrete

Features: o Production of a single item from each run

o Suited to small production quantities or producing unique, high-value items

o The highest level of information technology neededo The highest level of human involvement neededo Uses highly skilled human labour

Tasks they perform: o An automated carwash performs a series of operations on

the one car at a time.o When manufacturing the component parts in the custom-

made vehicle industry, all parts need to be made individually.

o Aeroplanes – different configurations for different countries Scheduling of tasks:

o A slower production rate. It produces items to a customer’s exact specification. This is designed for a slower production operation, dedicated to making only one product. If a second product is required, the system is restarted to repeat the operation.

o Be able to categorise and justify the categorisation of systems as either continuous, discrete or batch.

Continuous systems mass produce a single item continuously. Batch systems are similar but can be changed to produce other products. Discrete systems produce products one at a time.

Displaying:o Actuators – specialised display devices that perform a mechanical action under the

control of the system They perform the actual work of the system. An actuator is anything that

does work i.e. a physical device. Example would be the flashing lights, alarm in alarm system.

4 common features of actuators include: They are specialised display devices The ability to perform mechanical actions They receive an input from the controller/CPU Analog devices

o Types of actuators(be able to recommend a suitable actuator for a given situation and distinguish between situations suitable for the use of each type of actuator), including:

Solenoid A coil of wire around a moveable magnet. When an electric current

passes through a wire, a magnetic field is generated that will move the magnet. Washing machines use a solenoid to control the level of water entering the tub.

Suitable situations: The starter motor solenoid in a car, which engages the driver gear when the ignition key is turned to provide power; the water fill in washing machines is activated by a solenoid.

Motor Used to produce movement. They are the most commonly used

actuator, often combined with gears or lever systems. All electric motors operate via reactions between electric current in wires and magnets positioned around the wires. The result is a spinning of the central shaft due to the forces between the two sets of magnetic fields.

DC

motors are more versatile as their speed can be quickly altered. They also produce full power the instant they are switched on. AC motors run directly off the main power supply but cannot have their speed as easily adjusted. They produce full power only when they reach full speed.

DC motors: DC motors operate on current from batteries or a transformer. They allow easier control of the motor speed and provide a large starting force. They are capable of high precision and reliability.

Fan Air conditioner Washing machine

Dryer DVD player Microwave – little turntable that spins, driven by DC motor Television – fan inside to cool it down Oven – fan inside Vacuum Electrical lawnmowers Electric leaf blowers

No DC motors: Phones Toaster Iron Petrol lawnmowers

AC motors: AC motors are used when a constant motor speed is required. Stepping motor

Special motors that convert digital or pulsed signals into small step rotational movements. Are used in robots when precise open-loop is needed (that the desired position is calculated and then the device is told to go to that position) Very precise rotations, however it has low torque (power). Being controlled by pulsed signals, it makes interfacing with the computer easier, as each pulse is a binary signal which the computer can monitor without requiring a sensor. For example, computer disk drives use stepper motors for the precise control of the movement of the read/write heads, to locate tracks above the spinning floppy disks.

Relay A relay is a switching device. It is primarily used when a small

electric current is used to turn on/off a large electric current. The device is made from a solenoid in which a moveable magnet is connected to a mechanical switch, which is held in default position by a spring. When an electric current passes through the coil, the magnet moves against the spring and causes the switch to either open or close. The switch is usually connected to a more powerful electric source than the activation current for the coil, meaning a small voltage can control a much larger current or voltage switch, also meaning signal currents can be isolated from a much more dangerous current grid.

Suitable situation: To provide the interface between the low voltage circuitry and high voltage actuators such as motors.

Hydraulic pumps Used when great strength is needed. Uses a master piston/cylinder

containing a liquid that can be used in very high-pressure situations. The pressure the fluid exerts against other things creates power transmitted to a hydraulic device. This power is used to allow movement to several locations with little friction.

Suitable situation: The service station hoists that are used to lift cars are hydraulic.

o The conversion from digital to analog to control actuators Displaying data may require converting digital data from a computer system

into analog data for an output device. A digital-to-analog converter (DAC) does this. For example, when a computer is connected to an actuator, and the actuator is designed to accept voltages from 0 to 10 volts:

o Describe the process involved in converting a digital signal to an analog signal.

A DAC can convert the digital signals in the range 0 to 250 into voltage values from 0 to 10 (still using the above example). The mathematics required involves dividing the decimal number by 250 and then multiplying the result by 10. For example, if the computer sends a signal of 11111010, it is converted to 10 volts.

Transmitting and receiving – Identify noise in relation to signals within the system and recommend techniques for reducing it:

o Noise as the interference in a signal A signal is the physical form in which data is transmitted, such as pulses of

electricity or light. Noise is unwanted data or interference that reduces the quality of the

signal.o Causes of noise

A poorly designed system where other electrical equipment gives off unwanted high-frequency pulses.

Lightning strikes Overheating of electrical circuits

o Ways of correcting noise Good design to reduce the risk of noise e.g. keeping sensory cables away

from machinery Use of feedback to average out the signals Signal conditioning is the modification of a signal for normal usage. Shielding surrounding cables, equipment or controller reduces noise. Filters are used to get rid of noise and get a smooth signal.

Issues related to automated manufacturing systemsDiscuss the arguments for and against automation from society’s perspective:

The changing nature of work resulting from automation in manufacturing technologyo Replacement of people by an automated system. People have lost jobs, but

population increases and consumer demands for the products have minimised the loss. Workers who lose their job may be emotionally distressed, but automated systems do provide job opportunities for people with information technology skills.

o Automation places a greater emphasis on knowledge and technical skill than physical work. Examples of jobs related to these systems include machine operation and maintenance, operators, systems analysis and computer programming.

o Organisations are putting greater effort into job design, recognising that people have different preferences in the how their job is performed. They are providing opportunities for diversifying employee’s experiences and acquainting them with the manufacturing task.

Investigate the effect of de-skilling on participants in the information systemThe effects of de-skilling may include loss of a job due to automation, loss of pride in losing a skilled job, damage to self-esteem and sense or worth or value and problems related to retraining and reskilling.

The advantages of semi-automation by utilising skills of people which leads to job satisfaction, including:

o Flexibility Humans can adapt to extraordinary situations and sudden changes. The one worker can perform an extremely wide range of tasks under a

variety of different conditions. Many factories are multi-skilling their workers by giving them experience in a wide range of jobs. This increases their involvement and sense of participation in the production process. The workers regain pride in their work and show a greater interest in quality control.

o Common sense Humans are better at visualising and understanding old and new ideas.

A feature that computers do not have and may never possess. Workers can foresee problems and take appropriate actions.

o Ingenuity Humans are better at thinking of new ideas than machines. Humans have always been good problem solvers, a characteristic that

computers have not yet been able to match. In many factories, the workers play an important role in management decisions. Their views are sought on issues such as production planning, design changes and job scheduling. A worker with twenty years’ experience on the factory can sometimes see solutions to problems that sophisticated simulation software or an engineer with a university degree cannot.

Describe the positive and negative impacts of working in an automated industry.Working in an automated industry can be bad because it may cause de-skilling, resulting in the loss of jobs. Furthermore, many systems used are machine-centred, and simplify what the machines must do at the expense of the participants, which leads to a decline in job satisfaction. However, there are also positive impacts. As manufacturing becomes more automated, the role or position of the participants has altered, from large numbers of manual jobs to mainly supervisory and IT type positions, which is called re-skilling. Furthermore, current society has introduced human-centred systems, which aim to increase job satisfaction, combining human flexibility and ingenuity with machines’ ability to perform dull, repetitive tasks.

The need to develop systems that are human-centred and assist participants to complete tasks, as opposed to machine-centred system where humans assist machines

o Machine-centred systems simplify what machines do at the expense of humans. Participants are forced to follow complex and confusing procedures while still being expected to work at the same efficiency. Errors tend to be blamed on the participants. Human-centred systems are designed to make participants’ work as effective and satisfying as possible. Attention is given to the work environment and this has led to improved design of tools, machines and participants’ work positions.

Classify systems as either machine-centred or human-centred and justify the classification. Propose (and develop) human-centred information systems Describe situations where participants and automatic functions would work well together.

o Food industry – a person inspects the food as it passes along a conveyor belt, and machines move the poor-quality items away.

o Machinery used to pack and wrap heavy boxes while people move them using a fork-lift.

o Conveyor belts – People control the moving conveyor belts and fix any breakdowns, while machines inspect products for defections and remove faulty products.

The reliability and quality of performing repetitive tasks such as: automatic painting, spot welding, newspaper production and computer embroidery

o Automatic painting, where a program directs one or more robot spray guns through a series of rotations and other movements to completely coat selected items with paint. These guns are much more reliable and accurate in performing repetitive tasks.

o Spot welding, where thousands of metal parts on a production line need to be welded. The large number of products means that production quality will always be higher with automated tools.

o Newspaper production, where huge rolls of paper are drawn through large printing presses and then cut and positioned rapidly and automatically so that various editions are possible, something humans could not do as rapidly or accurately.

o Computer embroidery, where a program will automatically and accurately produce the required letters or images, which would take much longer for humans.

The improved safety as a result of automated manufacturingo Machines are doing dangerous jobs such as spot welding. Most systems include

safety-monitoring systems, for example, sensors may detect a hazard to people, and alert maintenance personnel or stop operation altogether. Paint fumes and contact with other chemicals, eye damage from welding, noise and chemicals absorbed in newspaper production and so on, are all avoided when machines perform such tasks.

o On the other hand, unsafe practices and design can cause accidents. For example, loud machines such as grinding machines are also dangerous. Protective gear should be worn e.g. earmuffs, face masks and protective clothing. General safety issues include adequate lighting, ventilation and fire safety measures.

Current and emerging trends in automated manufacturing systems, including:o The use of AMS for quality control

Quality has gone from a human inspection phase of production to an automated one to ensure that products are all meeting a predetermined standard. Automated production lines require continual monitoring of components and accurate measuring devices to maintain the required standards. A variety of sensors (maybe pressure or temperature) need to be incorporated into the process, along with actuators to adjust the components as necessary. Feedback is a very necessary aspect to prevent variation in products and therefore wastage.