Planificación Agregada

MPS

y

MRP

en manufactura

Dr. Walter López Moreno

Aggregate Planning

Objective is to minimize cost over the planning period by adjusting Production rates Labor levels Inventory levels Overtime work Subcontracting Other controllable variables

Determine the quantity and timing of production for the immediate future

Heizer 2010

Master production

schedule and MRP

systems

Detailed work

schedules

Process planning and

capacity decisions

Aggregateplan for

production

Aggregate Planning

Figure 13.2

Product decisions

Demand forecasts,

orders

Marketplace and

demand

Researchand

technology

Raw materials available

Externalcapacity

(subcontractors)

Workforce

Inventoryon

hand

Heizer 2010

The Planning Process

Figure 13.1

Long-range plans (over one year)Research & DevelopmentNew product plansCapital investmentFacility location/expansion

Intermediate-range plans (3 to 18 months)Sales planningProduction planning and budgetingSetting employment, inventory,

subcontracting levelsAnalyzing cooperating plans

Short-range plans (up to 3 months)Job assignmentsOrderingJob schedulingDispatchingOvertimePart-time help

Top executives

Operations managers

Operations managers, supervisors, foremen

Responsibility Planning tasks and horizon

Heizer 2010

The Planning Process

Figure 14.1

Change production

plan?Master production schedule

ManagementReturn oninvestmentCapital

EngineeringDesigncompletion

Aggregate production

plan

ProcurementSupplierperformance

Human resourcesManpowerplanning

ProductionCapacityInventory

MarketingCustomerdemand

FinanceCash flow

Heizer 2010

The Planning Process

Figure 14.1

Is capacity plan being

met?

Is execution meeting the

plan?

Change master

production schedule?

Change capacity?

Change requirements?

No

Execute material plans

Execute capacity plans

Yes

Realistic?

Capacity requirements plan

Material requirements plan

Master production schedule

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 common performance 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)

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

Can be expressed in any of the following terms:

Heizer 2010

MRP Structure

Figure 14.5

Output Reports

MRP by period report

MRP by date report

Planned order report

Purchase advice

Exception reports

Order early or late or not needed

Order quantity too small or too large

Data Files

Purchasing data

BOM

Lead times

(Item master file)

Inventory data

Masterproduction schedule

Material requirement

planning programs

(computer and software)

Heizer 2010

Benefits of MRP

1. Better response to customer orders

2. Faster response to market changes

3. Improved utilization of facilities and labor

4. 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

BOM Example

B(2) Std. 12” Speaker kit C(3)

Std. 12” Speaker kit w/ amp-booster1

E(2)E(2) F(2)

Packing box and installation kit of wire,

bolts, and screws

Std. 12” Speaker booster assembly

2

D(2)

12” Speaker

D(2)

12” Speaker

G(1)

Amp-booster

3

Product structure for “Awesome” (A)

A

Level

0

Heizer 2010

Lead Times

The time required to purchase, produce, or assemble an itemFor 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 Requirement Planning) 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 que están disponibles y asignadas (comprometidas) para la produccion. En algunos casos forman parte de un sistema de KANBAN.

Inventario

Lopez 2009

Compras

Planned order Receipt – 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 (Planned schedule receipt)

Planned order Release – 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

Haga la semana 2, 3 y 4 con los siguientes datos

Lopez 2009

ReferenciasHeizer/Render (2010) Principles of Operations Management, 6eOperations Management

Kerzner Harold, (2010) Project Management , A systems approach to planning, scheduling and control

López Walter, (2009) Proceso de planificación en manufactura