Bài giảng môn Quản trị kinh doanh - Chapter 7: Manufacturing planning and control

Manufacturing Planning and ControlMPC 6th EditionChapter 7Capacity Planning and ManagementCapacity planning and management addresses two managerial problems:Matching capacity to plans–by either providing sufficient capacity to execute the plan or adjusting the plan to meet available capacity.Consider the marketplace implications of faster throughput times–at the expense of reduced capacity utilization.AgendaRole of Capacity Planning in Master Planning & ControlThe primary objective of capacity planning techniques is to estimate capacity requirements early enough to be able to meet those requirementsFlawless execution of the capacity plan allows the firm to avoid unpleasant surprisesInsufficient capacity leads to deteriorating delivery performanceExcess capacity may be a needless expenseResourceplanningSales and operationsplanningDemandmanagementMaster productionschedulingDetailed materialplanningMaterial andcapacity plansShop-floorsystemsSuppliersystemsCapacity Planning in the MPC SystemResource planningRough-cut capacityplanningCapacity requirementplanningFinite LoadingInput/output analysisLong RangeMedium RangeShort RangeLinks to other MPC System ModulesCapacity Planning Using Overall Factors (CPOF)Simplest rough-cut capacity planning approach Data inputs from master production scheduleBased on planning factors from historical data (work center utilization, production standards)Overall labor- or machine-hour capacity requirements are estimated from MPS dataEstimate is allocated to work centers based on historical workloadsInherent inaccuracies may limit usefulnessCPOF ExampleTotal required capacity = (33*0.95)+(17*1.85) = 62.80Work center capacity = Historical percentage*Total required capacityCapacity BillsRough-cut capacity planning method that provides more direct link to individual end productsBill of capacity indicates total standard time to produce one unit of an end product (by work center)Master production schedule data is then used to estimate capacity requirements for each work centerRequires more data than CPOF procedureCapacity Bill ExampleStd. Setup hours are spread over the standard lot sizeTotal hours include both std. run time and std. setup timeCapacity Bill ExampleMPS quantities are multiplied by bill of capacity to determine work center capacity requirements by periodResource ProfilesRough-cut capacity planning technique that includes production lead time informationProvides time-phased projections of capacity requirements for individual work centersMore sophisticated approach but requires tracking of relatively short time periods (< 1 week)Resource Profile ExampleProduction of one unit of product A in period 5 requires production activity in periods 3, 4, and 5 and in work centers 100, 200, and 300Resource Profile ExampleRequirements (by work center and period) for one unit of end product are multiplied by the MPS plan to determine capacity requirementsThese requirements are then summed over all periods to finalize the processCapacity Requirements Planning (CRP)Capacity requirements planning differs from the rough-cut planning proceduresUtilizes time-phased material plan from MRPTakes into account materials in inventoryAccounts for the current status of work-in-processAccounts for service parts and other demands not accounted for in the MPSRequires more inputs and more computational resourcesCapacity Requirements Planning ExampleDetailed MRP DataScheduled/planned quantity multiplied by processing time for work centerThis process is repeated for each work center to complete the planScheduling Capacity and Materials SimultaneouslyCapacity requirements planning doesn’t consider capacity when planning materialsAssumes that capacity can be adjusted, given sufficient warningPlanning capacity and materials at the same time allows construction of a plan that works within current capacity constraintsFinite Capacity SchedulingSimulates job order start and finish times in each work centerEstablishes a detailed schedule for each job in each work centerWhen a work center’s capacity is not sufficient for all planned jobs, prioritization rules determine which jobs will be shifted to later timesFinite Capacity SchedulingProduct A does not consume all available capacityCombination of all products consumes all available capacity in several periodsPlanned orders are shifted to stay within capacity limitationsWork Center SchedulingVertical Loading–each work center is scheduled job by job without consideration of other work centersIncreases capacity utilization but may result in more partial job completionHorizontal Loading–jobs are scheduled through all work centers in order of priorityLower capacity utilization but generally a higher proportion of jobs are completed in a shorter time span (higher customer service levels)Finite Capacity SchedulingThe FCS plan is a simulationRandomness leads to actual times that don’t match scheduled timesShould the work center wait for a job that isn’t available on time (idleness = lost capacity)Over time, the accuracy of the plan deterioratesFrequent rescheduling may be needed to maintain accuracyRescheduling process is computationally expensiveAdvanced Production Scheduling (APS)Expands Finite Capacity Scheduling to the entire product structure (end products and sub-assemblies)Can lead to a significant reduction in lead timesRequires accurate scheduling parameters, flawless execution, and prompt recovery from any problemsCapacity ManagementCapacity Monitoring with Input/Output ControlPlanned inputs are determined by the capacity planning processPlanned outputs depend upon the nature of the work centerCapacity-constrained–planned output is determined by the processing rate of the work centerNon-capacity-constrained–planned outputs match planned inputsDifferences between plan and actual must be addressed (management by exception)Managing Bottleneck Capacity–Theory of ConstraintsCapacity Planning in the MPC SystemShort-term capacity planning problems can be reduced by well-executed production and resource planningEfficient use of sufficient capacity by a good shop-floor system reduces capacity issuesChoosing the Measure of CapacityCapacity can be measured in many waysLabor hours, machine hours, physical units, monetary unitsThe firm’s needs and constraints should determine the capacity measureTrendsShrinking portion of direct laborLess clear distinctions between direct and indirect laborReduced ability to change labor capacityOutsourcingFlexible automation/cellular technologiesUsing the Capacity PlanTwo broad choices are available when actual capacity and plan are mismatchedChange capacity–reduce or increase capacity as indicated (within constraints)Revise material plan–change requirements and/or timing to match available capacityThe amount of material that can be produced is limited by the available capacity, regardless of the material planPrinciplesCapacity plans must be developed concurrently with material plans if the material plans are to be realized.Capacity planning techniques must match the level of detail and actual company circumstances.Capacity planning can be simplified in JIT environments.Better resource and production planning processes lead to less difficult capacity planning processes.Better shop-floor systems reduce the need for short-term capacity planning.PrinciplesMore detailed capacity planning systems demand more data and database maintenance.When capacity does not match the requirements, it isn’t always capacity that should change.Capacity must be planned, but use of capacity must also be monitored and controlled.Capacity planning techniques can be applied to selected key resources.Capacity measures should reflect reasonable levels of output from key resources.Quiz – Chapter 7Which capacity planning activities are considered long-range plans? Short-range plans? Medium-range plans?Resource planning is most closely linked with which MPC element?The capacity planning using overall factors (CPOF) technique is likely to perform poorly in a just-in-time (JIT) environment? (True/False)Capacity requirements planning (CRP) ignores current finished goods and WIP inventory? (True/False)According to the Theory of Constraints, bottleneck and non-bottleneck work centers should be managed similarly? (True/False)