Bài giảng Quản trị kinh doanh - Chapter 5: Manufacturing planning and control

Manufacturing Planning and ControlMPC 6th EditionChapter 5Master Production SchedulingAn effective Master Production Schedule (MPS) provides the basis for making good use of manufacturing resources, making customer delivery promises, resolving trade-offs between sales and manufacturing, and attaining the firm’s strategic objectives, as reflected in the Sales and Operations Plan.AgendaWhat is Master Production Scheduling?MPS and the Business EnvironmentMPS TechniquesAvailable-To-PromiseMPS in Assemble-To-Order EnvironmentsMPS StabilityManaging the MPSMaster Production Scheduling and the Manufacturing Planning and Control SystemThe MPS is a statement of the specific products that make up manufacturing outputThe MPS is a translation of the sales and operations plan into producible products with their timing and quantities determinedThe MPS shows when products will be available in the futureAttributes of the Master Production ScheduleThe MPS is a statement of production, not of demandThe MPS is not a forecastThe MPS considers factors such as capacity constraints, costs of production, resource limitations, and the sales and operations planThe MPS is stated in terms of product specifications–usually part numbers which have specific bills of materials (BOM)In assemble-to-order environments, the MPS may be stated in terms of an “average” final productMPS and the Business EnvironmentIn a make-to-stock company, the MPS is a statement of how much of each end item to be produced and when it will be availableIn a make-to-order (or engineer-to-order) firm, the MPS is usually defined as the specific end item(s) that make up an actual customer orderIn an assemble-to-order firm, the large number of possible product combinations is represented with a planning bill of materialsMPS in the MPC SystemResourceplanningSales and operationsplanningDemandmanagementMaster productionschedulingDetailed materialplanningEnterprise Resource Planning (ERP) SystemFront EndEngineRough-cut capacityplanningMaster Production Scheduling LinkagesThe MPS is the driver of all detailed manufacturing activities need to meet output objectivesThe MPS is the basis for key inter-functional trade-offsProduction and salesFinancial budgets should be integrated with MPS activitiesMaster Production Scheduling Process and TechniquesDetermine supply and demand relationships over time (time-phased record)Prepare production schedule according to strategy (chase, level, mixed)Calculate projected available balance (for available-to-promise activities)Revise plans as time passes (rolling through time)Time-Phased RecordA means of gathering and displaying critical scheduling information (Forecast, available stock, production schedule)On handPeriod12345Forecast5581015Projected available balance202530323227Master production schedule1010101010MPS Process–with Lot SizingPeriod 1 – 5 planPeriodOn hand12345Forecast5581015Projected available balance20151032227Master production schedule30Lot size = 30 Safety stock = 5Period 2 – 6 planPeriodOn hand23456Forecast2020201520Projected available balance10-100-20-35-55Master production schedule30Lot size = 30 Safety stock = 5Order size driven by lot sizing constraint, order timing/quantity driven by safety stock constraintAs time progresses, new information becomes availableOn hand stock = On hand – actual demand + production= (20 + 0 – 10)Updated forecast for periods 2 – 6 changes projected available balancing, prompting reschedulingRevising the MPSPeriod 2 – 6 planPeriodOn hand23456Forecast2020201520Projected available balance10203010255Master production schedule303030Lot size = 30 Safety stock = 5Additional production orders in periods 2 and 5 to meet safety stock requirementsAvailable-to-PromiseWhen immediate delivery is not expected (or is not possible due to stockouts), a promised delivery date must be establishedThe order promising task is to determine when the shipment can be madeAvailable-to-promise (ATP) procedures coordinate order promising with production schedulesAvailable-to-Promise Logic–DiscreteDiscrete ATP treats each period independentlyPeriodOn hand12345Forecast5581015Orders53200Projected available balance20151032227Available-to-promise1228Master production schedule30Lot size = 30 Safety stock = 5Period 1: Total customer demand before next production = 8 unitsPeriod 1: ATP = available balance – customer orders = 20 -8Period 1: Projected available = Previous available + MPS – MAX(Forecast, Orders)Period 3: ATP = MPS – customer orders = 30 -2Period 3: Total customer demand before next production = 2 unitsAvailable-to-Promise Logic–CumulativeCumulative ATP carries ATP units forwardPeriodOn hand12345Forecast5581015Orders53200Projected available balance20151032227Available-to-promise1240Master production schedule30Lot size = 30 Safety stock = 5Period 1: Total customer demand before next production = 8 unitsPeriod 1: ATP1 = available balance – customer orders = 20 - 8Period 1: Projected available = Previous available + MPS – MAX(Forecast, Orders)Period 3: ATP3 = ATP1 + MPS – customer orders = 12+ 30 - 2Period 3: Total customer demand before next production = 2 unitsATP–Consuming the ForecastIn the ATP calculation, demand is considered to be the maximum of forecast and actual customer ordersThis is a conservative approachAssumes that we will eventually sell at least the forecast quantityAdjusts for periods where demand exceeds the forecastMPS in Assemble-to-Order EnvironmentsIn an assemble-to-order (ATO) environment, the possible combinations of end items can be hugeSpecific end item bills of materials (BOM) are replaced with a planning bill of materials, which represents the potential product combinationsOne type of planning BOM is the super bill, which describes the usage of options and components that make up the average productSuper Bill of MaterialsParts used in all configurations are listed with usage probability of 1.0Mutually exclusive option sets are listed together, with a usage probability for each optionSafety stock absorbs variations in actual mixAvailable-to-Promise Logic with Planning BOMCommon Parts Available?Gear Available?Taylor Available?Book orderTry 1 period laterNoNoNoYesYesYesAre the common parts on the BOM available?Is the requested gear option available?Is the requested Taylor option available?Two-Level Master Production SchedulesWhen a planning BOM is used, a final assembly schedule (FAS) is often usedStates the set of end products to be built over a time periodTwo-level MPS coordinates component production and the FASComponent production is controlled by aggregate production plan in the FASFinal assembly is controlled by the FASEither discrete or cumulative ATP logic can applyDiscrete ATP with a Two-Level Master Production Schedule4-Horsepower Tillers (Aggregate)PeriodOn hand12345Production Plan100100100100100Orders100725400Projected available balance000000Available-to-promise02846100100Master production schedule100100100100100Safety stock = 0Taylor Brand 4-HP Tillers (FAS)PeriodOn hand12345Forecast for model (40% of total)4040404040Orders42372300Projected available balance104888488848Available-to-promise482080Master production schedule808080Lot size = 80 Safety stock = 10Normal ATP logic applies to FAS items For planning BOM items projected available balance is always zero because the item doesn’t actually existPlanning BOM orders are the sum of FAS ordersMaster Production Schedule StabilityA stable MPS translates to stable component schedulesStability allows improved plant performanceExcessive MPS changes can lead to reduced productivityFailure to change the MPS can lead to reduced customer service and increased inventory (failure to react)Freezing the Master Production ScheduleInside the frozen horizon no order changes are allowedDemand Time FencePlanning Time FenceOnly occasional changesMinor changesMost changesManaging the Master Production ScheduleTo be controlled, the MPS must be realisticPeople should only be held accountable for attainable performance levelsStability and buffering are importantThe MPS must not be overstatedSum of the MPS should equal the production planPrinciplesThe MPS unit should reflect the business environment and the company’s chosen approach.If a common ERP database is implemented, the MPS function should use that data.Regardless of the firm’s environment, effective scheduling is facilitated by common systems, time-phased processing, and MPS techniques.Customer order processing should be closely linked to MPS.PrinciplesATP information should be derived from the MPS and provided to the sales department.An FAS should be used to convert the anticipated build schedule into the final build schedule.The master production scheduler should ensure that the sum of the parts (the MPS) is equal to the whole (the operations plan).Quiz – Chapter 5The Master Production Schedule (MPS) shows when products will physically be available to ship? (True or False)In which environment is a planning bill-of-material (BOM) most likely to be used?Available-to-promise (ATP) is likely to be least useful in which environment?A Super Bill represents average usage of components in an assemble-to-order environment? (True or False)When the master production schedule (MPS) is frozen for some period, changes to the plan within that period are typically prohibited?