DDE 3443DDE 3443
CHAPTER 1CHAPTER 1
INTRODUCTION TOINTRODUCTION TO
AUTOMATIONAUTOMATION
1
1.11.1 INTRODUCTIONINTRODUCTION
• The technology by which a process or procedure isThe technology by which a process or pr...
• To automate a process, power is required, both toTo automate a process, power is required, both to
drive the process its...
BASIC ELEMENT OF ANBASIC ELEMENT OF AN
AUTOMATED SYSTEMAUTOMATED SYSTEM
• Consists of 3 basic elements:Consists of 3 basic...
2)2) The controller (which ‘tells’ the actuator to doThe controller (which ‘tells’ the actuator to do
work)work)
• A contr...
3)3) The sensor (which provides feedback to theThe sensor (which provides feedback to the
controller so that it knows the ...
• Switches can detect when a measured condition exceeds aSwitches can detect when a measured condition exceeds a
pre-set l...
1.21.2 TYPE OFTYPE OF
AUTOMATIONAUTOMATION
• Hard AutomationHard Automation
• Controllers were built for specific purposes...
• Soft AutomationSoft Automation
• Modern digital computers are re-programmable.Modern digital computers are re-programmab...
• In other books/references, automation can beIn other books/references, automation can be
classified into three basic typ...
• The features of fixed automation;The features of fixed automation;
• High initial investment for custom-engineered equip...
• Programmable AutomationProgrammable Automation
• The production equipment is designed with theThe production equipment i...
• This changeover procedures takes time.This changeover procedures takes time.
• Examples: numerical control (NC) machine ...
• Flexible AutomationFlexible Automation
• An extension of programmable automation.An extension of programmable automation...
• Examples, flexible manufacturing systems forExamples, flexible manufacturing systems for
performing machining operations...
1.31.3 REASON FORREASON FOR
AUTOMATINGAUTOMATING
• To increase labor productivityTo increase labor productivity
• To reduc...
AUTOMATION CONTROLAUTOMATION CONTROL
• Usually implies a sequence of mechanical steps.Usually implies a sequence of mechan...
PROCESS CONTROLPROCESS CONTROL
• Usually implies that the product is produced in aUsually implies that the product is prod...
Production Quantity and ProductProduction Quantity and Product
VarietyVariety
• First, letFirst, let
• Q= production quant...
where P = total number of different part or product styles, and jwhere P = total number of different part or product style...
• P refers to the different product designs or types that areP refers to the different product designs or types that are
p...
Product and Part ComplexityProduct and Part Complexity
• Let nLet npp = the number of parts per product.= the number of pa...
• The total number of parts produced by the factory is given by :The total number of parts produced by the factory is give...
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Chapter1

  1. 1. DDE 3443DDE 3443 CHAPTER 1CHAPTER 1 INTRODUCTION TOINTRODUCTION TO AUTOMATIONAUTOMATION 1
  2. 2. 1.11.1 INTRODUCTIONINTRODUCTION • The technology by which a process or procedure isThe technology by which a process or procedure is accomplished without human assistance.accomplished without human assistance. • A technique that can be used to reduce costs and/or toA technique that can be used to reduce costs and/or to improve quality.improve quality. • Can increase manufacturing speed, while reducing cost.Can increase manufacturing speed, while reducing cost. • Can lead to products having consistent quality, perhapsCan lead to products having consistent quality, perhaps even consistently good qualityeven consistently good quality • It is implemented using a program of instructionsIt is implemented using a program of instructions combined with a control system that executes thecombined with a control system that executes the instructions.instructions. 2
  3. 3. • To automate a process, power is required, both toTo automate a process, power is required, both to drive the process itself and to operate the programdrive the process itself and to operate the program and control system.and control system. • Automated processes can be controlled by humanAutomated processes can be controlled by human operators, by computers, or by a combination of theoperators, by computers, or by a combination of the two.two. • If a human operator is available to monitor and controlIf a human operator is available to monitor and control a manufacturing process,a manufacturing process, open loop controlopen loop control maymay be acceptable.be acceptable. • If a manufacturing process is automated, then itIf a manufacturing process is automated, then it requiresrequires closed loop controlclosed loop control, also known as, also known as feedback controlfeedback control.. • Figure 1.1 shows example of open loop control andFigure 1.1 shows example of open loop control and closed loop control.closed loop control. 3
  4. 4. BASIC ELEMENT OF ANBASIC ELEMENT OF AN AUTOMATED SYSTEMAUTOMATED SYSTEM • Consists of 3 basic elements:Consists of 3 basic elements: 1)1) The actuator (which does the work)The actuator (which does the work) • Controlled by the controller.Controlled by the controller. • The actuator in an automated process may in fact be severalThe actuator in an automated process may in fact be several actuators, each of which provides an output that drivesactuators, each of which provides an output that drives another in the series of actuator.another in the series of actuator. • Some actuators can only be on and off. Other actuatorsSome actuators can only be on and off. Other actuators respond proportionally with the signal they receive from arespond proportionally with the signal they receive from a controllercontroller • Actuators can be selected for the types of inputs they require,Actuators can be selected for the types of inputs they require, either DC or AC.either DC or AC. 4
  5. 5. 2)2) The controller (which ‘tells’ the actuator to doThe controller (which ‘tells’ the actuator to do work)work) • A controlled system either may be a simple digital system orA controlled system either may be a simple digital system or an analog system.an analog system. • Digital and analog controllers are available ‘off the shelf’ soDigital and analog controllers are available ‘off the shelf’ so that systems can be constructed inexpensive and with littlethat systems can be constructed inexpensive and with little specialized knowledge required.specialized knowledge required. 5
  6. 6. 3)3) The sensor (which provides feedback to theThe sensor (which provides feedback to the controller so that it knows the actuator is doingcontroller so that it knows the actuator is doing work)work) • Obviously, controlled automation requires devices to senseObviously, controlled automation requires devices to sense system output.system output. • Sensors also can be used so that a controller can detect andSensors also can be used so that a controller can detect and respond to changing conditions in its working environment.respond to changing conditions in its working environment. • Switches and transducers are another name for sensors.Switches and transducers are another name for sensors. 6
  7. 7. • Switches can detect when a measured condition exceeds aSwitches can detect when a measured condition exceeds a pre-set level. Examples, closes when a workpiece is closepre-set level. Examples, closes when a workpiece is close enough to work on.enough to work on. • Transducers can describe a measured condition. Examples,Transducers can describe a measured condition. Examples, output increased voltage as a workpiece approaches theoutput increased voltage as a workpiece approaches the working zone.working zone. 7
  8. 8. 1.21.2 TYPE OFTYPE OF AUTOMATIONAUTOMATION • Hard AutomationHard Automation • Controllers were built for specific purposes and couldControllers were built for specific purposes and could not be altered easily.not be altered easily. • Early analog process controllers had to be rewired toEarly analog process controllers had to be rewired to be reprogrammed.be reprogrammed. • This controllers do what they are designed and built toThis controllers do what they are designed and built to do, quickly and precisely perhaps, but with littledo, quickly and precisely perhaps, but with little adaptability for change (beyond minor adjustments).adaptability for change (beyond minor adjustments). • Modification of hard automation is time-consumingModification of hard automation is time-consuming and expensive, since modifications can only beand expensive, since modifications can only be performed while the equipment sits idle.performed while the equipment sits idle. 8
  9. 9. • Soft AutomationSoft Automation • Modern digital computers are re-programmable.Modern digital computers are re-programmable. • It is even possible to reprogram them and test theIt is even possible to reprogram them and test the changes while they work.changes while they work. • Even if hardware changes are required to a softEven if hardware changes are required to a soft automation system, the lost time duringautomation system, the lost time during changeover is less than for hard automationchangeover is less than for hard automation 9
  10. 10. • In other books/references, automation can beIn other books/references, automation can be classified into three basic types:classified into three basic types: • Fixed AutomationFixed Automation • A system which the sequence of processing (orA system which the sequence of processing (or assembly) operations is fixed by the equipmentassembly) operations is fixed by the equipment configurations.configurations. • Each operations in the sequence is usually simple.Each operations in the sequence is usually simple. 10
  11. 11. • The features of fixed automation;The features of fixed automation; • High initial investment for custom-engineered equipmentHigh initial investment for custom-engineered equipment • High production ratesHigh production rates • Relatively inflexible in accommodating product variety.Relatively inflexible in accommodating product variety. • Examples, machining transfer lines and automated assemblyExamples, machining transfer lines and automated assembly machines.machines. 11
  12. 12. • Programmable AutomationProgrammable Automation • The production equipment is designed with theThe production equipment is designed with the capability to change the sequence of operations tocapability to change the sequence of operations to accommodate different product configurations.accommodate different product configurations. • The operation sequence is controlled by aThe operation sequence is controlled by a program, which is a set of instruction coded soprogram, which is a set of instruction coded so that they can be read and interpreted by thethat they can be read and interpreted by the system.system. • New programs can be prepared and entered intoNew programs can be prepared and entered into the equipment to produce new products.the equipment to produce new products. • The physical setup of the machine must beThe physical setup of the machine must be changed for each new products.changed for each new products. 12
  13. 13. • This changeover procedures takes time.This changeover procedures takes time. • Examples: numerical control (NC) machine tools,Examples: numerical control (NC) machine tools, industrial robots and PLC.industrial robots and PLC. • The features of programmable automation;The features of programmable automation; • High investment in general purpose equipment.High investment in general purpose equipment. • Lower production rates than fixed automation.Lower production rates than fixed automation. • Flexibility to deal with variations and changes in productFlexibility to deal with variations and changes in product configuration.configuration. • Most suitable for batch production.Most suitable for batch production. 13
  14. 14. • Flexible AutomationFlexible Automation • An extension of programmable automation.An extension of programmable automation. • Capable of producing a variety of parts/productsCapable of producing a variety of parts/products with virtually no time lost for changeovers from onewith virtually no time lost for changeovers from one part style to the next.part style to the next. • The features of flexible automation;The features of flexible automation; • High investment for custom-engineered system.High investment for custom-engineered system. • Continuous production of variable mixtures of products.Continuous production of variable mixtures of products. • Medium production rates.Medium production rates. • Flexibility to deal with product design variations.Flexibility to deal with product design variations. 14
  15. 15. • Examples, flexible manufacturing systems forExamples, flexible manufacturing systems for performing machining operations.performing machining operations. The relative positions of the three types ofThe relative positions of the three types of automation for different production volume andautomation for different production volume and product varieties are shown in Figure 1.2.product varieties are shown in Figure 1.2. 15
  16. 16. 1.31.3 REASON FORREASON FOR AUTOMATINGAUTOMATING • To increase labor productivityTo increase labor productivity • To reduce labor costTo reduce labor cost • To improve worker safetyTo improve worker safety • To improve product qualityTo improve product quality 16
  17. 17. AUTOMATION CONTROLAUTOMATION CONTROL • Usually implies a sequence of mechanical steps.Usually implies a sequence of mechanical steps. • A camshaft is an automation controller because itA camshaft is an automation controller because it mechanically sequences the steps in the operationmechanically sequences the steps in the operation of an internal combustion engine.of an internal combustion engine. • Manufacturing processes are often sequenced byManufacturing processes are often sequenced by special digital computers, known as programmablespecial digital computers, known as programmable logic controller (PLC).logic controller (PLC). • PLC can detect and can switch electrical signalsPLC can detect and can switch electrical signals on and off.on and off. 17
  18. 18. PROCESS CONTROLPROCESS CONTROL • Usually implies that the product is produced in aUsually implies that the product is produced in a continuous stream.continuous stream. • Often, it is a liquid that is being processed.Often, it is a liquid that is being processed. • Early process control system consisted of specially-Early process control system consisted of specially- designed analog circuitry that measured a system’sdesigned analog circuitry that measured a system’s output ( e.g., the temperature of liquid leaving a tank),output ( e.g., the temperature of liquid leaving a tank), and changed that input ( e.g., changing the amount ofand changed that input ( e.g., changing the amount of cool liquid mixed in) to force the output to stay at a presetcool liquid mixed in) to force the output to stay at a preset value.value. • Now, process control is accomplished using digitalNow, process control is accomplished using digital computers.computers. 18
  19. 19. Production Quantity and ProductProduction Quantity and Product VarietyVariety • First, letFirst, let • Q= production quantityQ= production quantity • P=product varietyP=product variety • Q refers to the number of units of a given part orQ refers to the number of units of a given part or product that are produced annually by a plant.product that are produced annually by a plant. • Let us identify each part or product style by using theLet us identify each part or product style by using the subscript j, so that Qsubscript j, so that Qjj =annual quantity of product style j=annual quantity of product style j (products/yr).(products/yr). • Then let QThen let Qff =total quantity of all parts or products made=total quantity of all parts or products made in the factory.in the factory. 19
  20. 20. where P = total number of different part or product styles, and jwhere P = total number of different part or product styles, and j is a subscript to identify products, j=1,2,…,Pis a subscript to identify products, j=1,2,…,P 20 ∑ = = P j jf QQ 1 QQjj and Qand Qff are related as follows :are related as follows :
  21. 21. • P refers to the different product designs or types that areP refers to the different product designs or types that are produced in a plant. It is a parameter that can be counted, and yetproduced in a plant. It is a parameter that can be counted, and yet we recognize that the difference between products can be greatwe recognize that the difference between products can be great or small.or small. • Hard product variety is when the products differ substantially.Hard product variety is when the products differ substantially. Refers to the number of distinct product lines produced by theRefers to the number of distinct product lines produced by the factory.factory. • Soft product variety is when there are only small differencesSoft product variety is when there are only small differences between products. Refers to the number of models in a productbetween products. Refers to the number of models in a product line.line. • Let us divide P into two levels, P1 represents hard product varietyLet us divide P into two levels, P1 represents hard product variety and P2 is for soft varietyand P2 is for soft variety 21
  22. 22. Product and Part ComplexityProduct and Part Complexity • Let nLet npp = the number of parts per product.= the number of parts per product. • Let nLet n00 = the number of operations or processing steps to make a= the number of operations or processing steps to make a partpart • Assuming that the number of product designs P are produced inAssuming that the number of product designs P are produced in equal quantities Q, all products have the same number ofequal quantities Q, all products have the same number of component ncomponent npp, and all components require an equal number of, and all components require an equal number of processing step nprocessing step n00. In this case, the total number of product units. In this case, the total number of product units produced by the factory given by :produced by the factory given by : 22 PQQf =
  23. 23. • The total number of parts produced by the factory is given by :The total number of parts produced by the factory is given by : 23 ppf PQnn =  And the total number of manufacturing operation cyclesAnd the total number of manufacturing operation cycles performed by the factory is given by :performed by the factory is given by : opof nPQnn =

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