2 Process design Direct Operations management Design Develop Deliver Supply network designLayoutand flowProcess technologyPeople, jobs and organizationProduct/service designFigure 4.1 The design activities in operations management
3 Key operations questions In Chapter 4 – Process design – Slack et al. identify the following key questions…What is process design?What objectives should process design have?How does volume and variety affect process design?How are processes designed in detail?What are the effects of process variability?
4 Nature and purpose of the design activity Products, services and the processes which produce them all have to be designed.Decisions taken during the design of a product or service will have an impact on the decisions taken during the design of the process which produces those products or services and vice versa.
5 Designing the product or service The design of products/services and processes are interrelated and should be treated togetherProducts and services should be designed in such a way that they can be created effectivelyDesigning the product or serviceProcesses should be designed so they can create all products and services which the operation is likely to introduceDesigning the processProduct/service design has an impact on the process design and vice versaFigure 4.2 The design of products/services and processes are interrelated and should be treated together
6 The overlap of activities is greater in service design Design of the productDesign of the processDesign of the serviceDesign of the processIn most service operations, the overlap between service and process design is implicit in the nature of serviceIn manufacturing operations overlapping the activities of product and process design is beneficial
7 Operations performance objective Typical process design objectives The impact of performance objectives on designOperations performance objectiveTypical process design objectivesQualityProvide appropriate resources, capable of achieving the specification of product of servicesError-free processingSpeedMinimum throughput timeOutput rate appropriate for demandDependabilityProvide dependable process resourcesReliable process output timing and volumeFlexibilityProvide resources with an appropriate range of capabilitiesChange easily between processing states (what, how or how much is being processed?)CostAppropriate capacity to meet demandEliminate process waste in terms of,excess capacityexcess process capabilityin-process delaysin-process errorsinappropriate process inputsTable 4.1 The impact of strategic performance objectives on process design objectives and performance
8 Operations performance objective Some benefits of good process design The impact of performance objectives on design (Continued)Operations performance objectiveSome benefits of good process designQualityProducts and service produced ‘on-specification’Less recycling and wasted effort within the processSpeedShort customer waiting timeLow in-process inventoryDependabilityOn-time deliveries of products and servicesLess disruption, confusion and rescheduling within the processFlexibilityAbility to process a wide range of products and servicesLow cost/fast product and service changeLow cost/fast volume and timing changesAbility to cope with unexpected events (e.g. supply or a processing failure)CostLow processing costsLow resource costs (capital costs)Low delay/inventory costs (working capital costs)Table 4.1 The impact of strategic performance objectives on process design objectives and performance (Continued)
9 Environmentally sensitive process design Some fundamental issues:The sources of inputs to a product or service. (Will they damage rainforests? use up scarce minerals? exploit the poor or use child labour?)Quantities and sources of energy consumed in the process. (Do plastic beverage bottles use more energy than glass ones? Should waste heat be recovered and used in fish farming?)The amounts and type of waste material that are created in the manufacturing processes. (Can this waste be recycled efficiently, or must it be burnt or buried in landfill sites?)The life of the product itself. If a product has a long useful life will it consume fewer resources than a short-life product?The end-of-life of the product. (Will the redundant product be difficult to dispose of in an environmentally friendly way?)
10 Designing processesThere are different ‘process types’.Process types are defined by the volume and variety of ‘items’ they process.Process types go by different names depending on whether they produce products or services.
11 Manufacturing process types ProjectDiverse/complexRepeated/dividedIntermittentContinuousProcess tasksProcess flowHighJobbingBatchVarietyMassContin-uousLowLowVolumeHighFigure 4.3 Different process types imply different volume–variety characteristics for the process
12 Service process types Process tasks Process flow High Diverse/ complexRepeated/ dividedIntermittentContinuousProcess tasksProcess flowHighProfessional serviceService shopVarietyMass serviceLowLowVolumeHighFigure 4.3 Different process types imply different volume–variety characteristics for the process (Continued)
13 Project processesOne-off, complex, large scale, high work content ‘products’.Specially made, ‘every one customized’.Defined start and finish: time, quality and cost objectives.Many different skills have to be coordinated.
14 Jobbing processesVery small quantities: ‘one-offs’, or only a few required.Specially made. High variety, low repetition. ‘Strangers every one customized’.Skill requirements are usually very broad.Skilled jobber, or team, complete whole product.
15 Batch processes Higher volumes and lower variety than for jobbing. Standard products, repeating demand. But can make specials.Specialized, narrower skills.Set-ups (changeovers) at each stage of production.
16 Mass (Line) processes Higher volumes than batch. Standard, repeat products (‘runners’).Low and/or narrow skills.No set-ups or almost instantaneous ones.
17 Continuous processesExtremely high volumes and low variety: often single product.Standard, repeat products (‘runners’).Highly capital-intensive and automated.Few changeovers required.Difficult and expensive to start and stop the process.
18 Professional service High levels of customer (client) contact. Clients spend a considerable time in the service process.High levels of customization with service processes being highly adaptable.Contact staff are given high levels of discretion in servicing customers.People-based rather than equipment-based.
19 Service shops Medium levels of volumes of customers. Medium, or mixed, levels of customer contact.Medium, or mixed, levels of customization.Medium, or mixed, levels of staff discretion.
20 Mass service High levels of volumes of customers. Low to medium levels of customer contact.Low, or mixed, levels of customization.Low, or mixed, levels of staff discretion.
21 Deviating from the ‘natural’ diagonal on the product-process matrix has consequences for cost and flexibilityManufacturing operations process typesService operations process typesHigh varietyLow volumeLow varietyHigh volumeProduct/service characteristicsProjectJobbingBatchMassContinuousProfessionalserviceServiceshopMore process flexibility than is needed, so high costLess process flexibility than is needed, so high costThe ‘natural’ line of fit of process to volume/variety characteristicsFigure 4.4 Deviating from the ‘natural’ diagonal on the product–process matrix has consequences for cost and flexibility Source: Based on Hayes and Wheelwright9
22 Product-process matrix – water meter example High varietyLow volumeLow varietyHigh volumeProduct/service characteristicsOriginal service with appropriate process characteristicsNew service, old process, so excess process flexibility and high costABProcess characteristicsNew service with new process having appropriate process characteristicsCThe ‘natural’ diagonal or ‘line of fit’Figure 4.5 A product–process matrix with process positions from the water meter example
23 Process mapping symbols Delay (a wait, e.g. for materials)Operation (an activity that directly adds value)Inspection (a check of some sort)Transport (a movement of some thing)Storage (deliberate storage, as opposed to a delay)Process mapping symbols derived from scientific managementDecision (exercising discretion)Process mapping symbols derived from systems analysisDirection of flowInput or output from the processActivityBeginning or end of process
24 Process map – ‘enquire to delivery’ at stage lighting firm Customer requestCheck availability fileSupply from stock ?Customer wants search ?SearchFind supplier ?Call customerReserve on availability fileKit wagon to storeAssemble kitCheck equipmentNeeds attention ?RepairPack for deliveryDeliver to customerSend customer guideConfirm to supplierStored equip.YNKit to workshopSupplier’s equipment to storeSupplierFigure 4.7 Process map for ‘enquire to delivery’ process at stage lighting operation
25 ‘Supply and install’ process mapped at three levels The operation of supplying and installing lighting equipmentThe outline process of supplying and installing lighting equipment‘Enquire to delivery’‘Collect and check’‘Install and test’File failure noteInform customerNRectify in time ?YRectifyNTo customer siteRoutine control checkSafety checkYPass check ?YJob sign-offReturn to baseCompliant ?InstallNThe detailed process of ‘Install and test’ activityYRectify in time ?NCall for helpRectifyFigure 4.8 The ‘supply and install’ operations process mapped at three levels
26 ‘Collect and check’ process – levels of process visibility Very high visibilityCheck it worked okCall customer to agree termsWorked ok ?Agree reportNYLine of interactionTake out equipmentHigh visibilityMedium visibilityTo siteTo baseLine of visibilityAmend usage recordsBack office – low visibilityPrepare reportNCheck and clean equipmentDid it work ok ?Equipment to storeYFigure 4.9 The ‘collect and check’ process mapped to show different levels of process visibility
27 Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT) Little’s law (a really quite useful law)Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT)Cycle time = 2 minsWIP = 10Throughput time = ?Throughput time = 10 × 2 minsThroughput time = 20 mins
28 Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT) Little’s law (a really quite useful law) (Continued)Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT)Need to mark 500 exam scripts in 5 days (working 7 hours a day). Takes 1 hour to mark a script. How many markers are needed?Throughput time = 5 days × 7 hours = 35 hours35 hours = 500 scripts × Cycle timesCycle time = hours500 scripts= 0.07 hoursNumber of markers = Work content = 1 hour =Cycle time0.07
29 Throughput efficiency Throughput efficiency is the work content of whatever is being processed as a percentage of its throughput time.Throughput efficiency =Work contentThroughput time× 100
30 X X X X X X X High utilization but long throughput times 5-15 minsArrival frequency (demand)Processing timeUtilization = <100% % Q = >0Arrival frequency (demand)XUtilization = 100 % Q = infinity9 minsXUtilization = 50 % Q = 020 minsX10 minsUtilization = 100 % Q = 030 mins10 minsProcessing timeUtilization = % Q = 0HighHigh utilization but long throughput timesLow utilization but short throughput timesReduce process variabilityProcess throughput time(or inventory)Average length of queueXXLowX20%40%60%80%100%Capacity utilizationFigure The relationship between process utilization and number of items waiting to be processed for constant, and variable, arrival and process times
31 Process utilization, waiting time and variability High utilization but long waiting timeAverage number of units waiting to be processedDecreasing variabilityAverage number of units waiting to be processedReduction in process variabilityXShort waiting time but low utilizationZY102030405060708090100102030405060708090100UtilizationUtilization(a) Decreasing variability allows higher utilization without long waiting times(b) Managing process capacity and/or variabilityFigure The relationship between process utilization and number of items waiting to be processed for variable arrival and activity times
32 Chapter 4 ‘end-of-chapter’ case Slide deck for Action Response CaseSource: Shutterstock/ Yuri Acurs
33 Cycle time = time between unit outputs Some process metricsActivity AActivity CActivity BActivity DActivity EActivity FActivity GThe individual activities that make up the process.The sequence of the activities and the flow between them.Unit time AUnit time BUnit time CUnit time EUnit time DUnit time GUnit time FThe time required for each activity (Unit time A, B, C, etc.).The ‘work in progress’ (wip) within the process.Cycle time = time between unit outputsThroughput timeThe ‘work content’ of the whole job (Unit time A + Unit time B + Unit time C, etc.).The number of staff allocated to the process.
34 Action response TASK Read the Action Response case and… Map the application processesIdentify the strengths and weaknesses of their processesHelp to suggest possible improvements
35 ARAPU process map 300/week Receipt clerks (4) (10 mins) 100/week Coding clerks(5)(20 mins)Secretaries(3)Assessors(7)(100 take 10 mins)(300 take 60 mins)CommitteePayment clerksDecline clerks(4)(3)(50 mins)(30 mins)Dispatch(2)(10 mins)
37 Cycle time, throughput time and work-in-progress Calculating the required cycle timeForecast demands during the period (A)Availability of productive time (B)Cycle time (C = B/A)Deciding how many staff are neededWork content of the task (D)Cycle time required (C)Number of staff (D/C)100480 mins4.8 mins55 mins4.8 mins11.46 (12)
38 For action response… 300 2,100 mins 7 mins 127.5 mins 7 mins Actual=25 Calculating the required cycle timeForecast demands during the period (A)Availability of productive time (B)Cycle time (C = B/A)Deciding how many staff are neededWork content of the task (D)Cycle time required (C)Number of staff (D/C)3002,100 mins7 mins127.5 mins7 minsActual=2518.21 (19)
39 Cycle time, throughput time and work-in-progress Little’s law (a really quite useful law)Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT)Cycle time = 2 minsWIP = 10Throughput time = ?Throughput time = 10 × 2 minsThroughput time = 20 mins
40 Throughput (TH) = Work-in-progress (WIP) × Cycle time (CT) For action response...Little’s lawThroughput (TH) = Work-in-progress (WIP) × Cycle time (CT)Cycle time = 7 minsCycle time = ?WIP = ?WIP = 2,000Throughput time = ?Throughput time = 2,000 × 7 minsThroughput time = 14,000 minsThroughput time = days
41 BalancingAn ideal balance where activities are allocated equally between stagesCycle time = 12 minsCycle time = minsStage 2Stage 1Stage 1Stage 2Stage 3Stage 4Stage 3Stage 4Balancing waste = 5 mins per unitBalancing waste =