Solution Manual for Automation, Production Systems, and Computer-Integrated Manufacturing, 4th Edition

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Solutions ManualforAutomation,Production Systems, andComputer Integrated ManufacturingFourthEditionMikell P. GrooverProfessor of Industrial and Systems EngineeringLehigh University200 West Packer AvenueBethlehem, Pennsylvania18015

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Ch01 Introduction-4e-A&S09-10, 09-20-20131-1Chapter 1INTRODUCTIONREVIEW QUESTIONS1.1What is a production system?Answer: As defined in the text, aproduction systemis a collection of people, equipment,and procedures organized to perform the manufacturing operations of a company.1.2Production systemsconsist of two major components. Name and briefly define them.Answer: The twomajor componentsgiven in the text are (1) facilities, which consist ofthe factory, the equipment in the factory, and the way the equipment is organized; and (2)manufacturing support systems, whicharethe procedures used by the company to manageproduction and to solve the technical and logistics problems encountered in orderingmaterials, moving the work through the factory, and ensuring that products meet qualitystandards. Product design and certain business functions are included among themanufacturing support systems.1.3What are manufacturing systems, and how are they distinguished from production systems?Answer: A manufacturing system is a logical grouping of equipmentin the factory and theworker(s) who operate(s) it. Examples include worker-machine systems, production lines,and machine cells. A production system is a larger system that includes a collection ofmanufacturing systems and the support systems used to manage them. A manufacturingsystem is a subset of the production system.1.4Manufacturing systems are divided into three categories, according to worker participation.Name the three categories.Answer: The three categories are (1) manual work systems, (2) worker-machine systems,and (3) automated systems.1.5What are the four functions included within the scope of manufacturing support systems?Answer: As identified in the text, the four functions are (1) business functions, (2) productdesign, (3) manufacturingplanning, and (4) manufacturing control.1.6Three basic types of automation are defined in the text. What is fixed automation and whatare some of its features?Answer:Fixed automationis a system in which the sequence of processing (or assembly)operationsis fixed by the equipment configuration. Each operation in the sequence isusually simple, but the integration and coordination of many such operations in one pieceof equipment makes the system complex. Typical features of fixed automation are (1) highinitial investment for custom-engineered equipment, (2) high production rates, and (3)relatively inflexible in accommodating product variety.1.7What is programmable automation and what are some of its features?Answer: Inprogrammable automation, the production equipment is designed with thecapability to change the sequence of operations to accommodate differentpart orproductconfigurations. The operation sequence is controlled by aprogram,which is a set ofinstructions coded so that they can be read andinterpreted by the system. Some of thefeatures of programmable automation are (1) high investment in general purpose

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Ch01 Introduction-4e-A&S09-10, 09-20-20131-2equipment, (2) lost production time due to changeovers of physical setup andreprogramming, (3) lower production rates than fixed automation, (4) flexibility to dealwith variations and changes in product configuration, and (5) most suitable for batchproduction.1.8What is flexible automation and what are some of its features?Answer:Flexible automationis an extension of programmable automation. A flexibleautomated system is capable of producing a variety of parts (or products) with virtually notime lost for changeovers from one part style to the next. There is no lost production timewhile reprogramming the system and altering the physicalsetup. Accordingly, the systemcan produce various mixes and schedules of parts or products instead of requiring that theybe made in batches.Features of flexible automation are (1) high investment for a custom-engineered system, (2) continuous production of variable mixtures of products, (3) mediumproduction rates, and (4) flexibility to deal with product design variations1.9What iscomputer-integrated manufacturing?Answer: As defined in the text,computer-integrated manufacturing(CIM) denotes thepervasive use of computer systems to design the products, plan the production, control theoperations, and perform the various information-processing functions needed in amanufacturing firm. True CIM involves integrating all of these functions in one systemthat operates throughout the enterprise.1.10What are some of the reasons why companies automate their operations?Answer: The reasons give in the text are (1) increase labor productivity, (2) reduce laborcost, (3) mitigate the effects of labor shortages, (4)reduce or eliminate routine manual andclerical tasks, (5)improve worker safety, (6) improve product quality, (7) reducemanufacturing lead time, (8) accomplish processes that cannot be done manually, and (9)avoid the high cost of not automating.1.11Identify three situations in which manual labor is preferred over automation.Answer: The five situations listed in the text are the following: (1) The task istechnologically too difficult to automate. (2) Short product life cycle. (3)Customizedproduct. (4) To cope with ups and downs in demand. (5) To reduce risk of product failure.1.12Human workers will be needed in factory operations, even in the most highly automatedoperations. The text identifies at least four types of work for which humans will be needed.Namethem.Answer: The four types of work identified in the text are (1) equipment maintenance, (2)programming and computer operations, (3) engineering project work, and (4) plantmanagement.1.13What is the USA Principle? What does each of the letters standfor?Answer: The USA Principle is a common sense approach to automation and processimprovement projects. U means “understand the existing process,” S stands for “simplifythe process,” and A stands for “automate the process.”1.14The text lists ten strategies for automation and process improvement. Identify five of thesestrategies.Answer: The ten strategies listed in the text are (1) specialization of operations, (2)

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Ch01 Introduction-4e-A&S09-10, 09-20-20131-3combined operations, (3) simultaneous operations, (4) integration of operations, (5)increased flexibility, (6) improved material handling and storage, (7) on-line inspection,(8) process control and optimization, (9) plant operations control, and (10) computer-integrated manufacturing (CIM).1.15What is an automation migration strategy?Answer: Asdefined in the text, anautomation migration strategyis a formalized plan forevolving the manufacturing systems used to produce new products as demand grows.1.16What are the three phases of a typical automation migration strategy?Answer: As defined in the text, the three typical phases are the following: Phase 1: Manualproduction using single-station manned cells operating independently. Phase 2: Automatedproduction using single-station automated cells operating independently. Phase 3:Automated integrated production using a multi-station automated system with serialoperations and automated transfer of work units between stations.

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Mfg Ops-4e-A&S10-17, 10-19-20122-1Chapter 2MANUFACTURING OPERATIONSREVIEW QUESTIONS2.1What is manufacturing?Answer: Two definitions are given in the text. The technological definition is thefollowing:Manufacturingis the application of physical and chemical processes to alter thegeometry, properties, and/or appearance of a given starting material to make parts orproducts.Manufacturing also includes the joining of multiple parts to make assembledproducts. The economic definition is the following: Manufacturing is the transformation ofmaterials into items of greater value by means of one or more processing and/or assemblyoperations.2.2What are the three basic industry categories?Answer: The three basic industry categories are (1)primary industries, whichare those thatcultivate and exploit natural resources, such as agriculture and mining; (2)secondaryindustries, whichconvert the outputs of the primary industries into products; they includemanufacturing, construction, and power generation; and (3) tertiary industries, whichconstitute the service sector of the economy; examplesinclude banking, retail,transportation, education, government.2.3What is the difference between consumer goods and capital goods?Answer:Consumer goodsare products that are purchased directly by consumers,such ascars, personal computers, TVs, tires, toys, and tennis rackets.Capital goodsare productspurchased by other companies to produce goods and supply services. Examples includecommercial aircraft, mainframe computers, machine tools, railroad equipment, andconstruction machinery.2.4What is the difference between a processing operation and an assembly operation?Answer:Aprocessing operationtransforms a work material from one state of completionto a more advanced state that is closer to the final desired part or product. It adds value bychanging the geometry, properties, or appearance of the starting material. Anassemblyoperationjoins two or more components to create a new entity, called an assembly,subassembly, or some other term that refers tothe joining process.2.5Name the four categories of part-shaping operations, based on the state of the starting workmaterial.Answer: The four categories are (1) solidification processes, (2) particulate processing, (3)deformation processes, and (4) material removal processes.2.6Assembly operations can be classified as permanent joining methods and mechanicalassembly. What are the four types of permanent joining methods?Answer: The joining processes are (1) welding, (2) brazing, (3) soldering, and (4) adhesivebonding.2.7What is the difference between hard product variety and soft product variety?Answer:Hard product varietyis when the products differ substantially. In an assembledproduct, hard variety is characterized by a low proportion of common parts among

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Mfg Ops-4e-A&S10-17, 10-19-20122-2products; in many cases, there are no common parts.Soft product varietyis when there areonly small differences between products. There is a high proportion of common partsamong assembled products whose variety is soft.2.8What type of production does a job shop perform?Answer: Low productionof specialized and customized products. The products aretypically complex, such asexperimentalaircraft and special machinery.2.9Flow line production is associated with which one of the following layout types:(a) cellularlayout, (b) fixed-position layout, (c) process layout, or (d) product layout?Answer: (d) Product layout.2.10What is the difference between a single-model production line and a mixed-modelproduction line?Answer: A single-model production linemakes products that are all identical. A mixed-model production line makes products that have model variations characterized as softproduct variety.2.11What is meant by the termtechnological processing capability?Answer:Technological processing capabilityof a plant (or company) is its available set ofmanufacturing processes. It includes not only the physical processes, but also the expertisepossessed by plant personnel in these processing technologies.PROBLEMSAnswers to problems labeled(A)are listedin the Appendix at the back of the book.2.1(A)Amanufacturingplant produces three product linesin one of its plants: A, B, and C.Each product line has multiple models:3models within product line A,5models within B,and7within C. Average annual production quantities ofmodelA is400 units,800 units formodelB, and500 units formodelC. Determine thenumberof (a)different product modelsand (b)total quantity of productsproducedannually inthis plant.Solution: (a) The total number of different product models producedisP=3+5+7=15different models(b)The total production quantity of all products made in the factoryisQf=3(400) +5(800) +7(500) =1200 +4000 +3500 =8700 unitsannually2.2Consider product line A inpreceding Problem 2.1. Its three models have an averageof46components each, and the average number of operations needed to produce each componentis 3.5. All components are made in the same plant. Determine the total number of (a)componentsproducedand (b) operationsperformed in the plant annually.Solution: (a) The total number ofcomponentsproducedis given by Eq. (2.7).npf=PQnp= 3(400)(46) =55,200 components(b) The total number of operations performed annually in the plant is given by Eq. (2.9).nof=PQnpno= 3(400)(46)(3.5) =193,200 operations2.3A company produces two products in one of its plants: A and B. Annual production ofProduct Ais 3600 units and of Product B is 2500 units. Product A has 47 components andProduct B has 52 components. For ProductA, 40% of the components are made in the plant,while 60% are purchased parts. For Product B,30% of the components are made in the plant,

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Mfg Ops-4e-A&S10-17, 10-19-20122-3while70% are purchased. For these two products taken together, what is the total number of(a)componentsmade in the plant and (b)componentspurchased?Solution: (a) The total number ofcomponentsproducedin the plantcan be determined usingEq. (2.3),adjusting it for the proportionsof each partmadein the factory:npf=3600(47)(0.40) + 2500(52)(0.30) = 67,680 +39,000 =106,680 partsmade in plant(b) Letnpp= the total number of parts purchased:npp= 3600(47)(0.60) + 2500(52)(0.70) =101,520 + 91,000 =192,520purchasedparts2.4(A)A product line has two models: X and Y. ModelXconsists of 4 components: a, b,c, andd. The number of processing operations required to produce these four components are 2, 3,4, and 5, respectively. Model Y consists of 3 components: e, f, and g. The number ofprocessing operations required to produce these three components are, 6,7, and 8respectively. The annual quantity of Model X is 1000 units and of Model Y is 1500 units.Determine the total number of (a) components and (b) processing operations associated withthese two models.Solution: (a) The total number ofcomponentscanbe determined using Eq. (2.3):npf=1000(4) + 1500(3) = 4000 + 4500 =8500 componentsAlternatively,Eq. (2.7) can be used, first computing the average values forQandnpusingEqs. (2.6) and (2.8).Q= (1000 + 1500)/2 = 1250 unitsnp= (1000(4) + 1500(3))/(2×1250) = 3.4 components per unit productnpf=2(1250)(3.4) = 8500 components(b)The total number of processing operations can be determined using Eq. (2.4):nof=1000(2 + 3 + 4 + 5) + 1500(6 + 7 + 8) = 1000(14) + 1500(21) =45,500 operationsAlternatively,Eq. (2.9) can be used, first computing the average values fornpandnousingEqs. (2.8) and (2.10).The value ofnpwas calculated above:np= 3.4 components per unit productno= (1000(2 + 3 + 4 + 5) + 1500(6 + 7 + 8))/3.4 = 5.353 operationsper componentnof= 2(1250)(3.4)(5.353) = 45,500 operations2.5The ABC Company is planning a new product line and a new plant toproducethe parts fortheline. The product line will include8different models. Annual production of each modelis expected tobe900 units. Each product will be assembled of180components. Allprocessing of parts will be accomplished inthe new plant.Onaverage,6processingoperationsarerequired to produce each component, and eachoperationtakesan average of1.0min(includingan allowance for setup time and part handling). All processing operationsare performed at workstations, each of which includes a production machine and a humanworker.Theplant operates one shift.Determinethe number of(a)components, (b)processing operations, and (c) workersthatwill beneededto accomplish the processingoperationsif each worker works 2000 hr/yr.Solution:(a)Number of componentsproduced in the plant:npf=PQnp=8(900)(180) =1,296,000 components(b)Number of operationsperformed in the plant:nof=PQnpno=8(900)(180)(6) =7,776,000 operationsin theplantper year(c) Total operation timeTT=nofTp, whereTp= time for one processing operation.TT= 7,776,000(1.0) = 7,776,000 min = 129,600 hr of processing time

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Mfg Ops-4e-A&S10-17, 10-19-20122-4At 2000 hours/yr per worker,number of workersw=129,600/2000=64.8workersThisshould be rounded up to65 workers.2.6The XYZ Company is planning a new product line and a new factory to produce the partsand assembly the final products. The product line willinclude 10 different models. Annualproduction of each model is expected to be 1000 units. Each product will be assembled of300 components, but 65% of these will be purchased parts (not made in the new factory).There are an average of8processingoperationsrequired to produce each component, andeach processing step takes 30 sec (includingan allowance for setup time and part handling).Each final unit of product takes48minto assemble. All processing operations are performedat work cells that include a production machine and a human worker. Products are assembledatsingle workstations consisting ofoneworkereachplus assembly fixtures and tooling.Each work cell and each workstation require 25m2of floor spaceandan additionalallowance of45%must be added to the total production area for aisles,work-in-processstorage,shipping and receiving,rest rooms,and other utility space. The factorywilloperateone shift (the day shift,2000 hr/yr). Determine (a) how manyprocessing and assemblyoperations, (b)how many workers(direct labor only), and (c)how muchtotalfloorspacewill be required in the plant.Solution: (a)The number of products isQf=PQ= 10(1000) = 10,000 products/yrTherefore, the number of final assembly operations =10,000asby ops/yrTotal number of partsnpf= 10(1000)(300) = 3,000,000 components, but 65% of these arepurchased, so the number made in the plant will be 0.35(3,000,000) = 1,050,000Number of processing operationsnof=1,050,000(8)=8,400,000 proc ops/yr(b) Total processing timeTTp=nofTp, whereTp= time for one processing operation.TTp= 8,400,000(0.50) = 4,200,000 min = 70,000 hr/yrTotal assembly timeTTa=QTa, whereTa= assembly time for each product.TTa= 10,000(48) = 480,000 min/yr =8000 hr/yrNumber of workersw= (70,000 +8000)/2000 =39workers(c) With 1 worker per workstation for processing operationsand 1 worker per assemblyworkstation,n=w=39workstations.Total floor spaceTA=nAw(1 +AL), whereAw= area of each work cell or workstation, andAL= allowance for aisles,storage,etc.TA= 39(25)(1 + 0.45) =1413.75m2(~15,217 ft2)2.7Supposethe company in Problem 2.6were to operatetwoshifts (a day shift and an eveningshift, a total of4000 hr/yr) instead of one shiftto accomplish the processing operations. Theassembly of the product would still be accomplished on the day shift. Determine(a) howmany processing and assembly operations, (b) how many workerson each shift (direct laboronly), and (c) how much total floor spacewill be required in the plant.Solution: (a) Number of final assembly operationsPQ= 10(1000)=10,000 asby ops/yrTotal number of partsnpf= 10(1000)(300) = 3,000,000 components, but 65% of these arepurchased, so the number made in the plant will be 0.35(3,000,000) = 1,050,000Number of processing operationsnof=1,050,000(8)=8,400,000 proc ops/yr(b) Total processing timeTTp=nofTp, whereTp= time for one processing operation.TTp= 8,400,000(0.50 min) = 4,200,000 min = 70,000 hr/yr total for two shiftsTTp= 70,000/2 = 35,000 hr/yr total for each shiftNumber of processing operation workers per shiftwp= 35,000/2000 = 17.5 rounded up to18parts production workers per shift

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Mfg Ops-4e-A&S10-17, 10-19-20122-5Total assembly timeTTa=QTa, whereTa= assembly time for each product.TTa= 10,000(48) = 480,000 min/yr = 8000 hr/yrNumber of assembly workerswa= 8000/2000 =4 assembly workersNumber of workers on day shiftw= 18 + 4 =22 workersNumber of workers on evening shiftw=18 workers(c)The floor space must be based onthe number of day shift operations, which includesprocessingand assembly operations.Total floor spaceTA=nAw(1 +AL), whereAw= area of each work cell or workstation, andAL= allowance for aisles, etc.TA= 22(25)(1 + 0.45) =797.5m2(~8584 ft2)Comment:This is asavings in floor space of ~44% compared to the one-shift operation inthe previous problem.

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Ch03MfgEco-4e-S10-29, 11-26-20123-1Chapter 3MANUFACTURING METRICSREVIEW QUESTIONS3.1What is the cycle time in a manufacturing operation?Answer: As defined in the text,the cycle timeTcis the time that one work unit spendsbeing processed or assembled. It is the time between when one work unit beginsprocessing (or assembly) and when the next unit begins.3.2What is a bottleneck station?Answer: The bottleneck station is the slowest workstation in a production line, and thereforeit limits the pace of the entire line.3.3What is production capacity?Answer:Production capacity is the maximum rate of output that a production facility (orproduction line, work center, or group of work centers) is able to produce under a given setof assumed operating conditions.3.4How can plant capacity be increased or decreased in the short term?Answer: As listed in the text, the two ways that plant capacity can be increased or decreasedin the short term are (1)add workers, (2)change the number of work shifts per weekSw, and(3) change the number of hours worked per shiftHsh.3.5How can plant capacity be increased or decreased in the intermediate or long term?Answer: As listed in the text, the two ways that plant capacity can be increased or decreasedin the intermediate or long term are (1) increase or decrease the number of work centers inthe plant or (2) increase the production rate of the work centers by making methodsimprovements or using more productive processing technologies.3.6What is utilization in a manufacturing plant? Provide a definition.Answer:Utilization is the proportion of time that a productive resource (e.g., a workcenter) is used relative to the time availableunder the definition of capacity. Expressingthis as an equation,iijjUf=∑whereUi= utilization ofmachinei, andfij= the fraction of time during the available hoursthat machineiis processing part stylej. An overall utilization for the plant is determinedby averaging theUivalues over the number of work centers:1nijiijjfUUnn===∑∑∑3.7Whatis availability and how is it defined?

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Ch03MfgEco-4e-S10-29, 11-26-20123-2Answer: Availability is a reliability metric that indicates the proportion of time that a pieceof equipment is up and working properly. It is defined as follows:A= (MTBF–MTTR)/MTBFwhereA= availability,MTBF=mean time between failures, andMTTR= mean time torepair.3.8What is manufacturing lead time?Answer:Manufacturing lead time is the total time required to process a given part orproduct through the plant, including any lost time due to delays, time spent in storage,reliability problems, and so on.3.9What is work-in-process?Answer:Work-in-process (WIP) is the quantity of parts or products currently located inthe factory that are either being processed or are between processing operations. WIP isinventory that is in the state of being transformed from raw material to finished product.3.10How are fixed costs distinguished from variable costs in manufacturing?Answer: Fixed costs remain constant for any level of production output. Examples includethe cost of the factory building and production equipment, insurance, and property taxes.Variable costs vary in proportion to the level of production output. As output increases,variable costs increase. Examples include direct labor, raw materials, and electric power tooperate the production equipment.3.11Name five typical factory overhead expenses?Answer: Table 3.2in the text lists the following examples of factory overhead expenses:plant supervision, applicable taxes, factory depreciation, line foremen, insurance,equipment depreciation, maintenance, heat and air conditioning, fringe benefits, custodialservices, light, material handling, security personnel, power for machinery, shipping andreceiving, tool crib attendant, payroll services, and clerical support.3.12Name five typical corporate overhead expenses?Answer:Table 3.3in the text lists the following examples of corporate overhead expenses:corporate executives, engineering, applicable taxes, sales and marketing, research anddevelopment, cost of office space, accounting department, support personnel, securitypersonnel, finance department, insurance, heat and air conditioning, legal counsel, fringebenefits, and lighting.3.13Why should factory overhead expenses be separated from corporate overhead expenses?Answer:A manufacturing company may operate more than one factory, and each factoryhasits own overhead expenses that are different from the expenses at other factories. Onthe other hand corporate overhead expenses are applied to all factories operatedby thecompany. Also, in matters of analyzing costs, corporate overhead would simply inflate theoperating costsso they should not be included in the cost analyses, but at least some of thefactory overhead costs should be included. Inpricing decisions,both factory and corporateexpenses must be included.3.14What is the capital recovery factor in cost analysis?

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Ch03MfgEco-4e-S10-29, 11-26-20123-3Answer:The capitalrecovery factor (A/P,i,N) converts an initial cost of an investment atyear 0 into a series of equivalent uniform annual year-end values, wherei=annualinterestrate andN= number of years in the service life of the equipment.PROBLEMSAnswers to problems labeled(A)are listed in the Appendix at the back of the book.Cycle Time and Production Rate3.1(A)A batch of parts is produced on a semi-automated production machine. Batch size is 200units.Setup requires 55 min. A worker loads and unloads the machine each cycle, whichtakes 0.44 min.Machine processing time is 2.86 min/cycle, and tool handling time isnegligible. One part is produced each cycle. Determine (a) average cycle time, (b) time tocomplete the batch, and (c) average production rate.Solution: (a)Th=0.44 min,To= 2.86 min,andTt= 0Cycle timeTc= 0.44+2.86=3.30min(b) Batch timeTb= 55 + 200(3.30) =715min=11.92 hr(c) Average production timeTp= 715/200 = 3.575 min/pcProduction rateRp= 60/3.575 =16.78 pc/hr3.2In a batch machining operation, setup time is 1.5hoursand batch size is 80 units. The cycletime consists of part handling time of 30 sec and processing time of 1.37 min.One part isproduced each cycle.Tool changes must be performed every 10 parts and this takes 2.0 min.Determine (a) average cycle time, (b) time to complete the batch, and (c) average productionrate.Solution: (a)Th=0.50 min,To= 1.37 min, andTt= 2.0/10 = 0.20 minCycle timeTc= 0.50 + 1.37 + 0.20 =2.07 min(b) Batch timeTb= 1.5(60) + 80(2.07) =255.6 min= 4.26 hr(c) Average production timeTp= 255.6/80 = 3.195 min/pcProduction rateRp= 60/3.195 =18.78 pc/hr3.3A batch production operation hasamachine setup time of 3.0hoursanda processing time of1.60 min per cycle. Two parts are produced each cycle. No tool handlingtime is included inthe cycle. Part handling time each cycle is 45sec. It consists of the workerobtaining twostarting work units from a parts tray, loading them into the machine, and then afterprocessing,unloading thecompleted unitsandplacing themintothe sametray. Each trayholds24work units.When all of the starting work units have been replaced with completedunits, the tray of completed parts is moved aside and a new tray of starting parts is movedinto position at the machine. This irregular work element takes 3.0 min. Batch quantity is2400 units. Determine (a) average cycle time, (b) time to complete the batch, and (c) averageproduction rate.Solution: (a)Th=0.75min/cycle,To= 1.60min, andTt=0.The irregular work element isan additional component of work handling time:Th2= 3.0/(24/2) = 0.25 minCycle timeTc= 0.75+ 1.60+ 0.25=2.60min(b)Batch timeTb= 3.0(60) + (2400/2)(2.60) = 180 + 3120 =3300 min= 55 hr(c) Average production timeTp= 3300/1200 = 2.75 min/cycle =1.375 min/pc

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Ch03MfgEco-4e-S10-29, 11-26-20123-4Production rateRp= 60/1.375 =43.64pc/hr3.4A flow line mass production operation consists ofeightmanualworkstations. Work units aremoved synchronouslyand automaticallybetween stations, with a transfer time of 15 sec. Themanualprocessingoperations performed at theeight stations take 40 sec, 52 sec, 43 sec, 48sec, 30 sec, 57 sec, 53 sec, and 49 sec, respectively. Determine (a) cycle time for the line, (b)time toprocessone work unitthrough the eight workstations, (c) average production rate,and (d) time to produce 10,000 units.Solution: (a)The longest processing operation time, MaxTo= 57 sec at station 6. It sets thepace for the rest of the line.Tc= 15 + 57 = 72 sec =1.2 min(b)Time to process one work unit through the eight workstations = 8(1.2) =9.6 min(c)Production rateRp= 60/1.2 =50pc/hr(d) Time to produce 10,000 units = 10,000/50 =200 hr3.5Average setup time on a certain production machine is4.0 hours. Average batch size is48parts, and average operation cycletime is 4.2 min. The reliability of this machine ischaracterized by mean time between failures of 37 hours and a mean time to repair of55min. (a) If availability is ignored, what is the average hourly production rate of the machine.(b) Taking into account the availability of the machine, determine its average hourlyproduction rate. (c) Suppose that availability only applied during the actual run time of themachine and not the setup time. Determine the average hourly production rate of themachine under this scenario.Solution: (a)Batch timeTb= 4(60) + 48(4.2) = 240 + 201.6 = 441.6 minTp= 441.6/48 = 9.2 min and production rateRp= 60/9.2 =6.52 pc/hr(b) AvailabilityA= (37–55/60)/37 = 0.975 = 97.5%Production rate including effect of availability =ARp= 0.975(6.52) =6.36 pc/hr(c) If availability only applies during run time, thenTb= 4(60) + 48(4.2/0.975) = 240 + 206.77 = 446.77 minTp= 446.77/48 = 9.31 min and production rateRp=6.45 pc/hrPlant Capacity and Utilization3.6(A)A mass-production plant hassixmachines andcurrentlyoperates one 8-hourshift perday, 5 daysper week, 50 weeksper year.Thesixmachinesproducethe same parteach at arate of12partsper hour. (a) Determine theannualproduction capacity of this plant. (b)If theplant were to operate three 8-hourshifts per day, 7 daysper week,52 weeksper year,determinetheannualpercentage increase in plant capacity?Solution:(a)From Table 3.1,Hpc= 2000 hrAnnual plant capacity using 50 weeks/yrPCy=2000(6)(12)=144,000 pc/yr(b)Working three 8-hr shifts/day, 7 days/wk,Hpc= 8736 hr.Annual plant capacityPCy=8736(6)(12)=628,992pc/wkThis is an increase of628,992/144,000–1 = 3.368 =336.8%Comment:Thisproblem illustrates the significant effect that hours of operation can haveon plant capacity.

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Solution Manual for Automation, Production Systems, and Computer-Integrated Manufacturing, 4th Edition - Page 15 preview image

Ch03MfgEco-4e-S10-29, 11-26-20123-53.7One million units of a certain product are to be manufactured annually on dedicatedproduction machines that run16hours per day, five days per week, 50 weeks per year. (a)If the cycle time of a machine to produce one part is 1.2minute, how many of thededicated machines will be required to keep up with demand? Assume that availabilityandutilizationare100%, and that setup timecan be neglected. (b) Solve part (a) except thatavailability = 90%.Solution:(a) Total workloadWL= 1,000,000(1.2min/60) =20,000hr/yrFrom Table 3.1, hours available/machine=4000 hrNumber of machinesn=(20,000 hr)/(4000 hr/machine)=5machines(b) AtA= 90%,n=(20,000 hr)/(4000×0.90)=5.55rounded up to6machines3.8A job shop has four machines and operates 40hours per week. During the most recentweek, machine 1 processed part A for 25hoursat a production rate of 10partsper hour,and part B for 12hoursat a rate of 7partsper hour. Machine 2 processed part Cfor 37hoursat a rate of14partsper hour, and was idle 3hours. Machine 3 processed part D for15hoursat a rate of20partsper hour,andpart E for25hoursat a rate of 15partsper hour.Machine 4 processed part F for 13hoursat a rate of 9partsper hour, part G for 12hoursata rate of 18partsper hour, and wasidlethe rest of the week.Determine(a)weeklyproductionoutputofthe shopand (b) average utilization of equipment.Solution:(a)For machine 1,f1A=25/40 =0.625andf1B=12/40 =0.30. For machine 2,f2C=37/40 =0.925. For machine 3,f3D=15/40 =0.375 andf3E=25/40 =0.625.For machine4,f4F=13/40 =0.325 andf4G=12/40 =0.30.Averageweeklyproduction rate isRph= 0.625(10) + 0.3(7) + 0.925(14) + 0.375(20) + 0.625(15)+ 0.325(9) + 0.3(18)Rph=46.5 pc/hrWeekly production rateRpw= 40(46.5) =1860pc/wk(b)0.6250.300.9250.3750.6250.3250.304U++++++==0.869 =86.9%3.9Abatch production plantworks 40 hours per week andhasthreemachines.In a typicalweek,fivebatches of partsareprocessed through thesemachines.Production rates,batchtimes, and operation sequences for the parts are given in the table belowforoneweek.(a)Determine the weekly production rate for the shop.(b)Is this weekly production rate equaltotheplant capacity?If not, determine what theoutputwould be ifallthreemachinescould be operated up to40 hoursper week,giventhe constraintthatno reductions inweekly production rates are allowedforany part.Use of a spreadsheet calculator isrecommendedforthis problem.Machine 1Machine 2Machine 3PartRp1(pc/hr)Tb1(hr)Rp2(pc/hr)Tb2(hr)Rp3(pc/hr)Tb3(hr)A1015151018.758B15141021C821D205254E165108Solution:(a) Current weekly output can be determined by multiplying theRpvalues by theTbvalues in each cell of the table. This is done in the following spreadsheet.

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Solution Manual for Automation, Production Systems, and Computer-Integrated Manufacturing, 4th Edition - Page 16 preview image

Ch03MfgEco-4e-S10-29, 11-26-20123-6PartRp1Tb1Rp2Tb2Rp3Tb3Batch sizeA150150150150B210210210C168168D100100100E808080Total708Total weekly output of the three machines is708pc/wkAlternative solution: Use Equation (3.13) to find thetime fractions out of 40 hr for eachpart and machine combination.This is done in the following spreadsheet, which alsocalculates thefijRpij/nojtermsin Equation (3.13).Partf1jf2jf3jRp1jRp2jRp3jnojf1jRp1j/nojf2jRp2j/nojf3jRp3j/nojA0.3750.250.2101518.7531.251.251.25B0.350.525151022.6252.625C0.525814.20D0.1250.1202521.251.25E0.1250.2161021.001.00Total0.851.00.9255.1257.704.875Weekly production rate isRppw= (40)(5.125 + 7.7 + 4.875) = 40(17.7) =708 pc/wk(b)Machine 2 is already operating 40 hr/wk, so no increases can be made in its weeklyproduction output. It producesparts A, C, D, and E, so the weekly quantities of these partsremain unchanged. The only part whose output can be increased is therefore part B,produced on machines 1 and 3.Machine 1 operates 34 hr/wk (85% utilization), so the hours devoted to the production ofpart B could be increased from 14 to 20 hr/wk. At a production rate of 15 pc/hr, thequantity produced by Machine 1 could be increased from 210 to 300.Machine 3 operates 37 hr/wk (92.5% utilization), so the hours devoted to the production ofpart B could be increased from 21 to 24 hr/wk. At a production rate of 10 pc/hr, thequantity produced by Machine 3 could be increased from 210 to 240.Machine 3 turns out to be the bottleneck in the operation sequencefor Part B, so thatmeans that Machine 1cannot be used the full 40 hr/wk. Any output beyond 240pc/wkcould not be processedby Machine 3 within the 40-hour week. Thus, 16 hours of time onMachine 1 will be devoted to Part B, thus increasing the hours of operation for Machine 1from 34 to 36(90% utilization). That still leaves 4 hours of unutilized time per week onMachine 1.Perhaps those 4 hours could be used to produce a sixth part (Part F).Plant capacity has been increased by 30 parts per week (output of Part B increases from210 pc/wk to240 pc/wk). Thus,PCw= 150 + 240 + 168 + 100 + 80 =738 pc/wk3.10There aretenmachines in the automatic lathe section of a certain machine shop. The setuptime on an automatic lathe averages5hours.Average batch size for parts processed throughthe section is100.Average operation time =9.0 minutes. Under shop rules, an operator canbe assigned to runone or twomachines. Accordingly, there arefiveoperators in the sectionfor thetenlathes. In addition to the lathe operators, there are two setup workers who performonlymachine setups. These setup workers are busy the full shift. The section runs one 8-hourshift per day,5days per week. Scrap losses are negligibleand availability = 100%. Theproduction control manager claims that the capacity of thesection should be2000partsper

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