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Planificación Agregada MPS y MRP en manufactura Dr. Walter López Moreno. Aggregate Planning. Determine the quantity and timing of production for the immediate future. Objective is to minimize cost over the planning period by adjusting Production rates Labor levels Inventory levels
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PlanificaciónAgregadaMPSy MRPen manufacturaDr. Walter López Moreno
Aggregate Planning Determine the quantity and timing of production for the immediate future • Objective is to minimize cost over the planning period by adjusting • Production rates • Labor levels • Inventory levels • Overtime work • Subcontracting • Other controllable variables Heizer 2010
Product decisions Research and technology Marketplace and demand Process planning and capacity decisions Demand forecasts, orders Workforce Raw materials available Aggregate plan for production Inventory on hand External capacity (subcontractors) Master production schedule and MRP systems Detailed work schedules Aggregate Planning Figure 13.2 Heizer 2010
Long-range plans (over one year) Research & Development New product plans Capital investment Facility location/expansion Top executives Intermediate-range plans (3 to 18 months) Sales planning Production planning and budgeting Setting employment, inventory, subcontracting levels Analyzing cooperating plans Operations managers Short-range plans (up to 3 months) Job assignments Ordering Job scheduling Dispatching Overtime Part-time help Operations managers, supervisors, foremen Responsibility Planning tasks and horizon The Planning Process Figure 13.1 Heizer 2010
Production Capacity Inventory Marketing Customer demand Finance Cash flow Procurement Supplier performance Human resources Manpower planning Management Return on investment Capital Engineering Design completion Aggregate production plan Change production plan? Master production schedule The Planning Process Figure 14.1 Heizer 2010
Master production schedule Change master production schedule? Change requirements? Material requirements plan Capacity requirements plan Change capacity? Realistic? No Is capacity plan being met? Is execution meeting the plan? Yes Execute capacity plans Execute material plans The Planning Process Figure 14.1 Heizer 2010
Objectives of master production scheduling are: ● To provide top management with a means to authorize and control manpower levels, inventory investment, and cash flow ● To coordinate marketing, manufacturing, engineering, and finance activities by a commonperformance objective ● To reconcile marketing and manufacturing needs ● To provide an overall measure of performance ● To provide data for material and capacity planning Kerzner 2010
Master Production Schedule (MPS) • Specifies what is to be made and when • Must be in accordance with the aggregate production plan • Aggregate production plan sets the overall level of output in broad terms • As the process moves from planning to execution, each step must be tested for feasibility • The MPS is the result of the production planning process Heizer 2010
Master Production Schedule (MPS) • MPS is established in terms of specific products • Schedule must be followed for a reasonable length of time • The MPS is quite often fixed or frozen in the near term part of the plan • The MPS is a rolling schedule • The MPS is a statement of what is to be produced, not a forecast of demand Heizer 2010
Master Production Schedule (MPS) Can be expressed in any of the following terms: • A customer order in a job shop (make-to-order) company • Modules in a repetitive (assemble-to-stock) company • An end item in a continuous (make-to-stock) company Heizer 2010
Data Files Output Reports MRP by period report BOM Master production schedule MRP by date report Lead times (Item master file) Planned order report Inventory data Purchase advice Material requirement planning programs (computer and software) Exception reports Order early or late or not needed Order quantity too small or too large Purchasing data MRP Structure Figure 14.5 Heizer 2010
Benefits of MRP Better response to customer orders Faster response to market changes Improved utilization of facilities and labor Reduced inventory levels Heizer 2010
Bills of Material • List of components, ingredients, and materials needed to make product • Provides product structure • Items above given level are called parents • Items below given level are called children Heizer 2010
Level Product structure for “Awesome” (A) 0 A Std. 12” Speaker kit w/ amp-booster 1 B(2)Std. 12” Speaker kit C(3) 2 Std. 12” Speaker booster assembly E(2) E(2) F(2) Packing box and installation kit of wire, bolts, and screws D(2) D(2) G(1) 3 Amp-booster 12” Speaker 12” Speaker BOM Example Heizer 2010
Lead Times • The time required to purchase, produce, or assemble an item • For purchased items – the time between the recognition of a need and the availability of the item for production • For production – the sum of the order, wait, move, setup, store, and run times Heizer 2010
Dibujo de Ensamblaje (Engineering Drawing) Lopez 2009
Estructura del Producto del Bill of Material Lopez 2009
Plan Agregado y el Itinerario Maestro de Producción (MPS – Master Production Schedule)
Entradas al MRP (Material RequirementPlanning) utilizando informes del BOM, Compras, Inventario y los tiempos de espera (Lead Times) Lopez 2009
BOM Lopez 2009
Inventario Quantity on hand – Es el inventario que esta disponible en el almacén. WIP – Material que esta en proceso de producción. Cantidad en el piso – Piezas sin labor queestán disponibles y asignadas (comprometidas) para la produccion. En algunoscasosforman parte de un sistema de KANBAN.
Inventario Lopez 2009
Compras PlannedorderReceipt– son los materiales que se planifican comprar de acuerdo a las futuras necesidades. En producciones que estan en proceso los ordenes deben estar en itinerario por recibir (Plannedschedulereceipt) PlannedorderRelease – Son las ordenes que se planifican con el suplidor para las fechas de recibo físicamente en las instalaciones. Estas dependen del lead time. Lopez 2009
Compras Lopez 2009
Requerimientos netos Lopez 2009
Requerimientos netos Lopez 2009
Requerimientos netos Lopez 2009
Tabla del plan de Ordenes de Envío (Release) y Recibos (Receipt) Lopez 2009
Tabla del plan de Ordenes de Envío (Release) y Recibos (Receipt) Lopez 2009
Referencias Heizer/Render (2010) Principles of Operations Management, 6e Operations Management Kerzner Harold, (2010) Project Management , A systems approach to planning, scheduling and control López Walter, (2009) Proceso de planificación en manufactura