Term
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Definition
| Collection of people, equipment, and procedures organized to accomplish the manufacturing operations of a company |
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Term
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Definition
| Include the factory, production machines, tooling, material handling equipment, inspection equipment, and the computer systems that control manufacturing operations. |
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Term
| Classifaction of Production Quantities |
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Definition
Low Production: 1-100 units anually
Medium Production: 100-10,000 units anually
High Production: 10,000-millions of units anually |
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Term
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Definition
-Refers to the different product designs or types that are produced in a plant.
-There is an inverse correlation between product variety and production quantity in terms of factory operations. |
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Term
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Definition
The product differs substantially.
Batch production methods are typically used. |
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Term
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Definition
| There are only small differences between products and product families that share common components. |
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Term
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Definition
-Typically a job shop facility
-Equipment in job shop is general purpose and the labor force is highly skilled
-Fixed Position Layout
-Process Layout |
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Term
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Definition
| -Workers and processing equipments are brought to the product, while the product remains in single location. -Used when product is large and hard to move. |
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Term
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Definition
-The equipment is arranged according to function or type.
-Each part requires a different operation sequence and routed through the departments in batches following the products process plan. |
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Term
| Medium Quantity Production |
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Definition
-Usually batch production
-Production rate of the equipment is greater than the demand rate of single product type so the same equipment is shared for multiple products.
-Setup or changeover time is lost production time which is a disadvantage of batch production.
-Cellular Manufacturing Layout |
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Term
| Cellular Manufacturing Layout |
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Definition
-Designed to support a limited variety of parts configurations.
-A part family is established (consisting of multiple products exhibiting soft product variety) which can flow through a common cellular manufacturing layout. |
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Term
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Definition
Quantity Production: involves mass production of single parts on single pieces of equipment
Flow Line Production: involves multiple workstations and the parts or assemblies are moved through sequence to complete production.
-This is called a Product Layout
--Single Model Production Line
--Mixed Model Production Line |
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Term
| Manufacturing Support Systems |
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Definition
| To operate the production facilities efficiently, a company must organize itself to design the processes and equipment, plan and control the production orders, and satisfy product quality requirements. |
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Term
| Information-Processing Cycle |
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Definition
1. Business Functions
2. Product Design
3. Manufacturing Planning
4. Manufacturing Control
Computer-Integrated Manufacturing(CIM) helps with this.
Also includes CAD/CAM |
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Term
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Definition
These are the principal means of communicating with the customer. This begins with a production order of one of the following:
-An order to manufacture an item to the customer's specification
-A customer order to buy one or more of the manufacturer's proprietary products
-An internal company order based on a forecast of future demand for proprietary product. |
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Term
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Definition
-If the product is to be designed as per customer specifications, the manufacturer's product design department will no be involved
-If the product is proprietary, the manufacturing firm is responsible for development and design |
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Term
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Definition
| This includes process planning, master production scheduling, material requirements planning and capacity planning |
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Term
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Definition
-shop floor control
-inventory control
-quality control |
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Term
| Automation in Production Systems |
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Definition
Automation can be defined as technology concerned with the application of mechanical, electronic, and computer-based systems to operate and control production.
-Automation of manufacturing systems
-computerization of the manufacturing support systems |
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Term
| Automated Manufacturing Systems |
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Definition
Manufacturing systems are called automated because they perform their operations with a reduced level of human participation compared with the corresponding manual process.
It aims to reduce the amount of manual and clerical effort in the Information-Processing Cycle.
-Fixed automation
-Programmable automation
-Flexible automation
-reconfigurable automation |
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Term
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Definition
-high initial investment for custom-engineered equipment
-high production rates and quantities
-relatively inflexible in accommodating product variety |
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Term
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Definition
-high investment in general purpose equipment
-lower production rates than fixed automation(low and medium volume production)
-flexibility to deal with variations and changes in product configurations
-most suitable for batch production |
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Term
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Definition
-high investment for custom-engineered system
-continuous production of variable mixtures of products
-medium production rates
-flexibility to deal with product design variations
-virtually no lost time for changeovers
-differences between parts processed by system are not significant(soft product variety) |
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Term
| Reconfigurable Automation |
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Definition
-high investment for common reusable system components
-rapid system implementation and decommissioning of the automated system
-low to medium production rates and product lives
-reconfigurable to support an evolving and dynamic mix of products
-advocates the used of modular and reusable system building blocks |
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Term
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Definition
-to increase labor productivity
-to reduce labor cost
-to mitigate the effects of labor shortages
-to reduce or eliminate routine manual and clerical tasks
-to improve worker safety
-to improve product quality
-to reduce manufacturing lead time
-to accomplish processes that cannot be done manually
-to avoid the high cost of not automating |
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Term
| Reasons for Manual Labor in Production Systems |
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Definition
-hourly wages are too low to justify automation
-task is to technologically difficult to automate
-short product life cycle
-customized product
-to cope with ups and downs in demands
-to reduce risk of product failure
-equipment maintenance
-programming and computer operation
-engineering project work
-plant management |
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Term
| Automation Principles and Strategies |
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Definition
-USA Principle
-The ten strategies for automation and production systems
-an automation migration strategy |
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Term
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Definition
-Understand the existing process
-Simplify the process
-Automate the process |
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Term
| The Ten Strategies for Automation and Production Systems |
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Definition
-specialization of operations
-combined operations
-simultaneous operations
-integration of operations
-increased flexibility
-eliminate material handling and storage
-in process inspection
-process control and optimization
-plant operations control
-computer integrated manufacturing |
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Term
| An Automation Migration Strategy |
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Definition
A formalized plan for evolving the manufacturing systems used to produce new product as demand grows.
phase1: Manual Production
phase2: Automated Production
phase3: Automated Integration Production
-Allows introduction of new product in shortest possible time
-Allows automation to be introduced in planned phases
-Avoids the commitment to a high level of automation from the start |
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Term
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Definition
defined as the application of physical and chemical processes to alter the geometry, properties and/or appearance of given starting material to make parts or products.
-includes joining of multiple parts to make assembled products
-transformation of materials into items of greater value by means of process and/or assembly operations |
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Term
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Definition
-man's discovery and invention of materials and processes to make things
-the development of systems of production
-Bronze Age (circa 3500 - 1500 BC)
-Iron Age (starting around 1000 BC)
-Industrial Revolution (circa 1760-1830)
--Marked the beginning of the change from economy based on agriculture and handicraft to one based on industry and manufacturing |
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Term
| Contributions of Industrial Revolution to development of Manufacturing |
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Definition
-Watt's steam engine, a new power generating technology
-Development of machine tools
-Invention of spinning jenny, power loom, and other machinery for textile
-Factory system, a new way of organizing large labor
-Wilkinson's boring machine is generally recognized as beginning of machine tool technology
-Maudsley's screw cutting lathe(1800)
-Interchangeable parts manufactured in the US
-Eli Whitney, 1797, negotiated contract to produce 10,000 muskets for the US gov't using a collection of special machines, fixtures, and gauges that he developed in his factory |
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Term
| Second Industrial Revolution |
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Definition
developments during the mid-late 1800s
-mass production
--primarily American phenomenon created for large population and demand for large quantities of products
-assembly lines
--Henry Ford, 1913
-scientific management movement
--motion study, time study, standards, data collection, record keeping
-electrification of factories
--1881, began with first electric power generation and in 1920 it replaced steam power |
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Term
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Definition
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Term
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Definition
Consists of enterprises and organizations that produce and/or supply goods and/or services.
Primary industries-cultivate and exploit natural resources such as agriculture and mining
Secondary industries-convert the outputs of the primary industries into products
Tertiary industries-constitute the service sector of the economy |
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Term
| Process and Discrete Product Industries |
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Definition
Process industries(ISIC 31-37) include chemicals, pharmaceuticals, petroleum, basic metals, food, beverages, and electric power generation.
Discrete product industries(ISIC 38&39) include automobiles, aircraft, appliances, computers, machinery, and the components parts that the products are assembled from.
-ISIC(International Standard Industrial Classification)
-Either continuous production or batch production |
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Term
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Definition
Consumer goods are products purchased directly by consumers such as cars, personal computers, etc.
Capital goods are products purchased by other companies to produce goods and supply services such as commercial aircraft, mainframe computers, and machine tools.
-Some companies are the industry that primarily produce materials, components, and supplies for companies that make final products(The final customer never deals with these suppliers. |
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Term
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Definition
-Processing and Assembly operations
-material handling
-inspection and testing
-coordination and control(represents the major point of intersection between the physical operations and information processing activities that occur in production. |
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Term
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Definition
transforms a work material from one state of completion to a more advanced state that is closer to the final desired part of product.
Shaping operations-solidification processes, particulate processing, deformation processing, and material removal processing
Property enhancing operations-sintering
Surface processing operations-cleaning, surface treatments, coating, and thin film deposition processes |
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Term
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Definition
joins two or more components to create a new entity.
-Machine assembly methods are available to fasten two or more parts together. |
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Term
| Key Parameters that Influence in Determining How the Products are Manufactured |
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Definition
-Production Quantity
-Product Variety
-Complexity of assembled products
-Complexity of individual parts |
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Term
Totality of product models equation
(Production Quantity and Product Variety) |
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Definition
Let P1(hard product variety)=number of distinct product lines produced by factory
Let P2(soft product variety)=number of models in product line
P= P1 SUMMATION j=1 P2*j |
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Term
Product and Part Complexity
(type of plant) |
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Definition
-The more parts the more complex a product
-A possible measure of part complexity is the number of processing steps required to produce it
np=number of parts per product
no=number of operation to make a part
type of plant parameter values
parts producer Np=1 No>1
assembly plant Np>1 No=1
vertically integrated plant Np>1 No>1 |
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Term
| Total number of parts manufactured by the plant per year equation |
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Definition
Npf=total number of parts made in the factory (pc/yr)
Qj=annual quantity of product style j (products/yr)
Npj=number of parts in product j (pc/product)
Npf= P SUMMATION j=1 Qj*Npj |
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Term
| Total number of processing operation performed by the plant equation |
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Definition
Nof=total number of operation performed in the factory (ops/yr)
Nojk=number of processing operation for each part k, summed over the number of parts in product j, Npj
Npj=numerical value for the totals activity level in the factory
Nof= P SUMMATION j=1 Qj*Npj * Npj SUMMATTION k=1 Nojk |
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Term
| Product/Production Relationships |
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Definition
if all products and equal Np and equal No
-total number of product units
Qf=P*Q
-total number of parts
Npf=P*Qnp
-total number of manufacturing operation cycles performed
Nof=P*Q*Np*No |
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Term
| Limitations and Capabilities of a Manufacturing Plant(Focused Factory) |
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Definition
focused factory is a plant which concentrates "on a limited, concise, manageable set of products, technologies, volumes, and markets" and typically limited to 500 workers
-Technological processing capability
-physical size and weight of product
-production capacity |
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Term
| Technological processing capability |
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Definition
-available set of manufacturing processes
-closely related to the material being processed
-by specializing in a certain process, the plant is simultaneously specializing in a certain range of materials
-includes not only the physical processes, but also the expertise processed by plant personnel in the processing technologies. |
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Term
| Physical Product Limitations |
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Definition
-Given a plant with a certain set of processes, there are size and weight limitations on the products that can be accommodated.
-also includes limitations of the manufacturing equipment
-material handling, storage capability, and plant size all must be planned for products that lie within a certain size and weight |
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Term
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Definition
-maximum rate of production per period that a plant can achieve under assumed operating conditions
-plant capacity is measured in terms of output units
-output units like annual tons of steel or number of cards produced are homogeneous
-not homogeneous in cases like available labor hours or productive capacity of a machine shop |
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Term
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Definition
-fixed cost(FC) is one that remains constant for any level of production output(Q)
-variable cost(VC) is one that varies in proportion to the level of production output(Q)
Total Cost=FC+(VC*Q)
FC of automated method is high relative to manual method
VC of automation is low relative to manual method. |
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Term
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Definition
the sum of wages and benefits paid to the workers who operate the production equipment and perform the processing and assembly tasks
DLC=annual direct labor costs($/yr) |
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Term
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Definition
| the cost of all raw materials used to make the product |
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Term
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Definition
All of the other expenses associated with running the manufacturing firm
-Factory overhead
FOHR=FOHC/DLC
-Corporate overhead
COHR=COHC/DLC |
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Term
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Definition
consists of direct labor and machine costs
Uniform Annual Cost
IC=initial cost of machine($)
A/P,i,n=capital recovery factor
UAC=IC(A/P,i,n) |
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Term
| Total Cost rate for the work center |
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Definition
CL=direct labor wage rage($/hr)
FOHRL=factory overhead rate for labor
CM=machine hourly rate($/hr)
FOHRM=factory overhead rate applicable to machines
Co=CL(1+FOHRL)+CM(1+FOHRM) |
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Term
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Definition
Technology by which a process or procedure is accomplished without human assistance.
It is implemented using a program of instructions combined with a control system that executes the instructions. |
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Term
| Three Basic Elements of an Automated System |
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Definition
-power source, controls, programmable machines
-Power and the capacity to generate it and transmit it to operate a process
-The flying-ball governor was one of the first examples in engineering of feedback control
-the actions of the system or machine to be directed by a program of instructions
-Jacquard loom was one of the first examples of machine programming |
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Term
| Early 1800's Inventions in Automation |
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Definition
-Interchangeable parts
-Electrification
-Moving assembly line
-mechanized transfer lines for mass production
-mathematical theory of control systems
-MARK I electromechanical computer |
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Term
| Coining of the word Automation |
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Definition
-Del Harder around 1946 referenced it to the many automatic machines found at the Ford Motor Company
-First commercial robot was installed to unload parts in die casting operation in 1961 |
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Term
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Definition
-principle source of power is electricity
used for:
-required for loading and unloading
-material transport between operations
-controller unit
-power to actuate the control signals |
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Term
| Program of Instructions(Basic Elements) |
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Definition
Work Cycle Program-the particular processing steps for the work cycle are specified here(Called part programs in numerical control)
Process Parameters-inputs to the process, such as temp setting of furnace, coordinate axis value in a positioning system, valve opened or closed in a fluid flow system, and motor on or off.
-process variables are outputs from the process such as the actual temp of the furnace, the actual position of the axis, the actual flow rate of the fluid in pipe and the rotational speed of motor
-in earlier versions of these operations, the work cycles were controlled by hardware components such as limit switches, timers, cams, and electro-mechanical relays.
-the hardware components directed the sequence of steps in processing cycle |
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Term
| Disadvantages of Using Hardware Components |
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Definition
-they often required considerable time to design and fabricate thus forcing the production equipment to be used for batch production only
-making even minor changes in the program was difficult and time consuming
-the program was in a physical form that is not readily compatible with computer data processing and communication
HOWEVER
-the use of digital computers as the process controller allows improvements and upgrades to be made in the control programs, such as the addition of control functions not forseen during initial equipment design |
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Term
| Decision-Making in the Programming |
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Definition
Decisions have to cope with variations that occur in the cycle.
These decisions are already incorporated into the regular program.
CASES INCLUDE
-operator interaction
-different part or product styles processed by the system
-variations in the starting work units
WHEN the variations are not routine,
-the program must include contingency procedures or modifications in the sequence to cope with conditions that lie outside the normal routine |
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Term
| Features of Work Cycle Programs |
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Definition
-steps in work cycle
-process parameters(inputs) in each step
-manual steps in work cycle
-operator interaction
-different part or product styles
-variations in starting work units |
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Term
| Control System(Basic Elements) |
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Definition
The control system executes the program of instructions
-causes the process to accomplish its defined function which is some manufacturing operation
-either closed or open loop |
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Term
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Definition
Feedback control sytem
-the output variable is compared with the input parameter and any difference is used to drive the output into agreement with input |
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Term
| Open Loop and When its Appropriate |
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Definition
operates without the feedback
-risk is that the actuator will not have the intended effect on the process
-advantage is that its simpler and less expensive than closed loop
APPROPRIATE WHEN
-the actions performed by the control systems are simple
-the actuating function is very reliable
-the reaction forces opposing the actuation are small enough to have no effect on the acuation |
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Term
| Advanced Automated Functions |
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Definition
-safety monitoring
-maintenance and repair diagnostics
-error detection and recovery |
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Term
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Definition
involves the use of sensors to track the systems operation and identify conditions and events that are unsafe or potentially unsafe
REASONS FOR
-to protect human workers in vicinity of system
-to protect the equipment associated with the system |
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Term
| Responses to Safety Monitoring |
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Definition
-complete stoppage of the automated system
-sounding an alarm
-reducing the operating speed of the process
-taking corrective actions to recover from the safety violation |
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Term
| Possible Sensor for Safety Monitoring |
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Definition
-limit switches
-photoelectric sensors
-temperature sensors
-heat or smoke detectors
-pressure sensitive floor-pads
-machine vision systems |
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Term
| Maintenance and Repair Diagnostics |
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Definition
refers to the capabilities of an automated system to assist in the identification of the source of potential or actual malfunctions and failures of the system
-usually difficult for repair crews to determine reason for failure
-the computer is programmed to monitor and record the variables and to draw logical inferences from their values about the reason for malfunction
-another function also tries to detect signs of impending failure so affected components can be replaced before failure.
MODES OF OPERATION
-status monitoring
-failure diagnostics
-recommendation of repair procedure |
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Term
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Definition
POSSIBLE ERRORS
random errors-occur as a result of the normal stochastic nature of the process
systematic errors-result from some assignable cause such as a change in raw material properties or a drift in an equipment setting
aberrations-result from either and equipment failure or a human mistake |
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Term
| Problems in Error Detection |
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Definition
-to anticipate all of the possible errors that can occur in a given process
-to specify the appropriate sensor systems and associated interpretive software so that the system is capable of recognizing each error
-if an error has not been anticipated, then the error can not be identified and corrected |
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Term
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Definition
concerned with applying necessary corrective action to overcome the error and bring the system back to normal operation
STRATEGIES
-make adjustments at the end of the current work cycle
-make adjustments during the current work cycle
-stop the process to invoke corrective action
-stop the process and call for help
error detection and recovery requires and interrupt system |
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Term
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Definition
-device level
-machine level
-cell or system level
-plant level
-enterprise level |
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Term
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Definition
| a collection of integrated equipment designed for some special mission, such as machining a defined part family or assembly of a certain product |
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Term
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Definition
the people, equipment, and procedures that are organized for the combination of materials and processes that comprise a company's manufacturing operation
-support procedures which includes production and inventory control, material requirements planning, shop floor control, and quality control |
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Term
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Definition
The automatic regulation of unit operations and their associated equipment as well as the integration and coordination of the unit operations into the larger production system.
-Unit Operations refers to manufacturing operations and also applies to the operation of material handling and other industrial equipment |
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Term
| Process Industries vs Discrete Manufacturing Industries |
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Definition
-process industries perform their production operations on amounts of materials.(mostly continuous control)
-discrete manufacturing industries perform their operations on quantities of materials.(mostly discrete control)
Graph in NOTES |
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Term
| Continuous Variable(Parameter) |
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Definition
one that is uninterrupted as time proceeds during the operation
-generally considered to be analog, which means it can take on any value within a certain range |
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Term
| Discrete Variable(Parameter) |
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Definition
one than can take on only certain values within a given range
-most common types are binary, meaning it can take on either of two possible values
-some variables can take on more than two values but less than infinite number
-pulse data is a special form of discrete variable
-pulse train might be used to indicate piece counts
-as process parameter, pulse train might be used to drive a stepper motor |
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Term
| Continuous Control Systems |
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Definition
The objective is to maintain the value of an output variable at a desired level, similar to the operation of feedback control system
-regulatory control
-feedforward control
-steady state optimization
-adaptive control |
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Term
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Definition
objective is to maintain process performance at a certain level or within a given tolerance band of that level
-in many applications the performance measure of the process is sometimes called the index of performance
-problem with this control is that compensating action is taken only after a disturbance has affected the process output
-mostly process industries
SEE GRAPH IN NOTES |
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Term
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Definition
strategy is to anticipate the effect of disturbances that will upset the process by sensing them and compensating for them before they can affect the process
-however complete compensation is unlikely b/c of imperfections in the feedback measurements, actuator operations, and control algorithms
-mostly process industries |
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Term
| Steady-State Optimization |
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Definition
refers to a class of optimization techniques that include:
-there is a well defined index of performance, such as product cost, production rate, or process yield
-the relationship between the process variables and the index of performance is known
-the values of the system parameters that optimize the index of performance can be determined mathematically
-this control system is open loop |
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Term
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Definition
-a self-correcting form of optimal control which is used to prevent disturbances
-different from feedback and steady-state b/c of its unique capability to cope with a time-varying environment
-not unusual for a system to operate in an environment that changes over time and for it to have potential effects on the system performance
-designed to compensate for changes in the environment by monitoring performance and altering some aspect of its control mechanism to achieve optimal performance |
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Term
| Adaptive Control Functions |
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Definition
Identification Functions-the current value of the index of performance of the system is determined based on measurements collected from the process
Decision Function-it is implemented by means of the adaptive system's programmed algorithm
Modification Function-it is concerned with physical changes in the system. it involves hardware rather than software. |
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Term
| On-Line Search Strategies and Other Specialized Techniques |
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Definition
-it can be used to address a special class of adaptive control problem in which the decision function cannot be sufficiently defined
-mostly used in continuous process industries
OTHER TECHNIQUES
-learning systems
-expert systems
-neural networks
-other artificial intelligence methods for process control |
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Term
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Definition
the parameters and variables of the system are changed at discrete moments in time.
-changes are defined in advance by means of a program of instructions such as a work cycle program
TYPES OF CHANGES
-event driven changes
-time driven changes
The two types of change correspond to two different types of discrete control called combination logic control and sequential control.
All of these systems operate by following a well defined sequence or start-and-stop actions. |
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Term
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Definition
executed by the controller in response to some event that has caused the state of the system to be altered.
-a robot loads a workpart into the fixture and the part is sensed by a limit switch
-the diminishing level of plastic molding compound in the hopper of an injection molding machine triggers a low-level switch, which in turn triggers a valve to open that starts the flow of new plastic in the hopper
-counting parts moving along a conveyor past an optical sensor |
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Term
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Definition
executed by the control system either at a specific point in time or after a certain time lapse has occurred.
change usually consists of starting something or stopping something, and the time when the change occurs is important
-"shop-clock" being set to sound a bell at specific moments to indicate the start and stop time for the shift and uniform break periods for all workers in factories
-automatic loading and unloading of parts into the furnace for the specified length of time in an automated heat treating cycle |
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Term
| Computer Process Control(Historical Note) |
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Definition
-the process control operated by making adjustments in the set points of analog controllers is call as set point control
-the feature in which the computer suspends current program execution to quickly respond to a process need is known as interrupt feature
-certain analog devices are replaced by the computer in DDC(direct digital control) system
-distributed control is the availability of low-cost microcomputers and PLC's resulted in growing number of installations in which a process was controlled by multiple computer networked together |
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Term
| Control Requirements(Real-Time) |
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Definition
a real-time controller is able to respond to the process within a short enough time period that process performance is not degraded
FACTORS TO DETERMINE IF REAL-TIME IS POSSIBLE
-the speed of the controller's CPU and its interfaces
-the controller's operating system
-the design of the application software
-the number of different input/output events to which the controller is designed to respond |
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Term
| Requirements That Must Be Managed By the Controller for Real-Time Control |
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Definition
-controller must be able to multi-task
-process initiated interrupts
-computer commands to process
-system and program initiated evenets
-operator initiated events |
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Term
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Definition
-scanning sensor values from the process at regular sampling intervals
-turning on and off switches, motors, and other binary devices associated with process at discrete points in time during work cycle
-displaying performance data on the operator's console at regular times during a production run
-re computing optimal process parameter values at specified times |
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Term
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Definition
| involve the communications among computers and peripheral devices linked together in a network |
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Term
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Definition
| when some non-process-related action is called for in the program, such as the printing of display of reports on a printer or monitor |
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Term
| Operator-Initiated Events |
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Definition
-entering new programs
-editing existing programs
-entering customer data, order number, or start-up instructions for next production run
-request for process data
-emergency stop |
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Term
| Capabilities of Computer Control |
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Definition
-polling
-interlocks
-interrupt system
-exception handling |
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Term
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Definition
refers to the periodic sampling of data that includes the status of the process
-also called sampling and scanning
ISSUES
-polling frequency
-polling order
-polling format |
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Term
| Alternatives of Polling Format |
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Definition
-entering all new data from all sensors and other devices every polling cycle
-updating the control system only with data that have changed since the last polling cycle
-using high level and low level scanning or conditional scanning |
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Term
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Definition
A safeguard mechanism for coordinating the activities of two or more devices and preventing one device from interfering with others
-in process control it provides a means by which the controller is able to sequence the activities by making sure one action is done before starting another |
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Term
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Definition
a signal that originates from an external device and is sent to the controller
USED FOR
-to proceed with the execution of the work cycle program
-to interrupt the execution of the work cycle program
An output interlock is a signal sent from the controller to some external device |
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Term
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Definition
A computer control feature that permits the execution of the current program or subroutine in response to an incoming signal indicating a higher priority event.
When interrupt signal is received, the computer system transfers a predetermined subroutine designed to deal with the specific interrupt.
The status of the current program is remembered so that its execution can be resumed when the servicing has completed. |
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Term
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Definition
-internal interrupts are generated by the computer system itself
-external interrupts are external to the computer system; they include process-initiated interrupts and operator inputs
-a single level interrupt system has only two modes of operation; normal and interrupt mode
-a multilevel interrupt system has a normal operating mode plus more than one interrupt level |
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Term
| Levels of Industrial Control |
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Definition
posses a hierarchical structure consisting of multiple levels of functions, similar to our levels of automation
-basic control
-procedural control
-coordination control |
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Term
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Definition
| Includes functions such as feedback control, polling, interlocking, interrupts, and certain exception handling actions |
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Term
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Definition
Functions are concerned with executing the work cycle program in an ordered sequence to accomplish some productive task.
May also involve executing error detection and recovery procedures and making decisions regarding safety hazards that occur during the process. |
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Term
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Definition
Initiates, directs, or alters the execution of programs at the procedural control level.
Its actions and outcomes change over time, as in procedural control, but its control algorithms are not structured for a specific process-oriented task.
Its more reactive and adaptive. |
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Term
| Functions of Coordination Control at Cell Level |
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Definition
-coordinating the actions of groups of equipment or machines
-coordinating material handling activities between machines in a cell or system
-allocating production orders to machines in the cell
-selecting among the alternative work cycle programs |
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Term
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Definition
-In process monitoring, the computer is used to simply collect data from the process, while in process control, the computer regulates the process
-in some process control implementation, certain actions are implemented by the control computer that require no feedback data to be collected from the process. ie. open loop control
-in most cases some form of feedback or interlocking is required to ensure that the control instructions have been properly carried out. ie. closed loop control |
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Term
| Forms of Computer Process Control |
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Definition
-computer process monitoring
-direct digital control
-numerical control and robotics
-programmable logic controllers
-supervisory control
-distributed control systems and personal computers |
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Term
| Computer Process Monitoring |
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Definition
involves the use of computer to observe the process and associated equipment and to collect and record data from the operation
CATEGORIZED INTO
-process data that indicates process performance
-equipment data that indicates the status of the equipment in the work cell
-product data that indicates the production data. Government regulations require certain manufacturing industries to collect and preserve these data |
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Term
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Definition
Certain components in a conventional analog control system are replaced by the digital computer.
New components in the loop include the digital computer, ADC's and DAC's, multiplexers to share data from different control loops with the same computer.
-more control options than traditional analog
-integration and optimization of multiple loops
-ending the control programs
This has motivated the use of distributed control systems.
Has mad the original concept of DDC obsolete.
The use of computer process control is economically justified for much smaller scale processes and equipment |
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Term
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Definition
Involves the use of microcomputer to direct a machine tool through a sequence of processing steps defined by a program of instructions that specifies the details of each step and their sequence.
NC requires the controller to execute not only the sequence control but geometric calculations as well |
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Term
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Definition
The joints of the manipulator are controlled to move the end-of-arm through a sequence of positions during the work cycle.
The controller must perform calculations during the work cycle to implement motion interpolation, feedback control, and other functions.
A robotic work cell usually includes the other equipment besides the robot, and the activities of the other equipment in the work cell must be coordinated with those of the robot. This is achieved using interlocks. |
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Term
| Programmable Logic Controllers(PLC) |
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Definition
Introduced around 1970 as an improvement on the electromechanical relay controllers used at the time to implement discrete control in the discrete manufacturing industries.
Modern PLC can be defined as a micro-processor based controller that uses stored instructions in programmable memory to implement logic, sequencing, timing, counting, and arithmetic control functions for controlling machines and processors. |
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Term
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Definition
Represent a higher level of control than the other forms of process control.
This type of control is interfaced directly to the process.
Is often superimposed on the process level control systems and directs their operations.
In discrete manufacturing, it can be defined as the control system that directs and coordinates the activities of several interacting pieces of equipment in a manufacturing cell or a system, such as a group of machines interconnected by a material handling system.
In virtually all cases, it is designed to allow for interaction with human operators, and the responsibility for control is shared between the controller and human. |
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Term
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Definition
An integrated circuit chip containing the digital logic elements needed to perform arithmetic calculations, execute instructions stored in memory and carry out other data processing tasks.
IMPACTS
Distributed control Systems
The use of personal computers in control systems
The basic functions performed by the microcomputer consist of data manipulation and computation, carried out according to software stored in memory to accomplish user applications |
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Term
| Important Distinction between a PC and a Controller is that a Controller must: |
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Definition
-capable of interacting with the process being controlled
-able to accept data from sensors connected to the process
-able to send command signals to actuators attached to the process
These transactions are made possible with an I/O capability |
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Term
| Distributes Control Systems(DCS) |
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Definition
With the development of the microprocessor, it became feasible to connect multiple microcomputers together to share and distribute the process control workload.
CONSISTS OF THE FOLLOW FEATURES
-process stations
-central control room
-local operator stations
-communications network or data highway |
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Term
| PC's in Process Control(definition) |
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Definition
Two basic categories of PC application in process control are
-Operator interface
-Direct control
The PC is interfaced to one or more PLC's or other devices that directly control the process. The computer performs certain monitoring and supervisory control functions, but does not directly control the process |
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Term
| Advantages of using a PC as the only operator interface: |
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Definition
-PC provides user friendly interface for he operator
-PC can be used for all of the conventional computing and data processing functions that PC's traditionally perform
-PC failure will not disrupt control of the process as the PLC or other device that directly controls the process is isolated from the PC
-the computer can be easily upgraded as PC technology advances and capabilities improve |
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Term
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Definition
-Direct control means that the PC is interfaced directly to the process and control its operations in real time
-if the computer might fail, the uncontrolled operations might stop working
-conventional PC's equipped with the usual business-oriented operating system and applications software are designed for computing and data-processing functions and not for process control
-most PC's are designed to be used in an office environment, not in the harsh factory atmosphere |
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Term
| Factors that Enable the us of PC's for Direct Control of Industrial Processes: |
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Definition
-familiarity with PC's
-high performance of PC's
-open architecture philosophy in control systems design
-Microsoft's Windows NT as the operating system of choice |
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Term
| PC's in Process Control(Trends) |
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Definition
-For the last 20 years, it has been observed that processor speed doubles every 12-18 months. This trend called Moore's Law is expected to continue for at least another 15 years.
-At the same time, processor costs have decreased by several orders of magnitude, and this trend is expected to continue as well.
-New generations of PC's are currently being introduced more rapidly than PLC's are, allowing cycle speeds of PC's to exceed those latest PLC's. |
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Term
| PC's in Process Control(architecture) |
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Definition
-open architecture philosophy means that components from different vendors can be interconnected in the same control system
-open architecture allows the user a wider choice of products in the design of a given process control system |
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