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Material Requirements Planning


Material Requirements Planning Chapter 7 Vollmann, Berry, Whybark, Jacobs What is MRP (Material Requirements Planning) Is a basic tool for performing the detailed ... – PowerPoint PPT presentation

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Title: Material Requirements Planning

Material Requirements Planning
  • Chapter 7
  • Vollmann, Berry, Whybark, Jacobs

What is MRP (Material Requirements Planning)
  • Is a basic tool for performing the detailed
    material planning function in the manufacture of
    component parts and their assembly into finished

Objective of MRP
  • To provide the right parts at the right time to
    meet the schedules for completed products.

  • Requires MPS
  • Requires Bill of Materials
  • Requires Inventory Status data
  • Routing file
  • Figure 7.1scan

The Basic MRP Record (7.2)scan(per ciascun
oggetto, sia esso materia prima, componente o
prodotto finito) pp. 225-227
  • Anticipated usage of demand for each period
    (GROSS REQUIREMENTS richiesta complessiva)
  • Existing replenishment orders ordini di
    rifornimento at the beginning of period
  • The current and projected inventory status at the
  • Planned dallo scheduler, si aggiungono ai
    receipts replenishment orders for the beginning
    of each period (PLANNED ORDER RELEASES)

Product Structure Diagram (7.3, 7.4)
  • It is a technique used to describe the
    relationship between the components of a product
    and the way these components and parts are put
    together in order to make a complete unit.
  • Pegging record Tutti I componenti a tutti I
    livelli dell BOM possono essere marcati, oltre
    che con il proprio part number, anche con quello
    del componente di livello superiore a cui
    appartengono. I prodotti finali anche con il
    numero dordine del cliente.

Gross to Net Explosion esplosione dal complessivo
allordito netto, cioè tenendo conto del
disponibile, ovvero InventoryScheduled
  • Explosion is the process of translating product
    requirements into component part requirements
    taking existing inventories and scheduled
    receipts into account.
  • As the explosion takes place only the components,
    net of any inventoryScheduled are considered.
    This way only the necessary requirements are
    linked thru the system.
  • 7.5scan

Lead Time Offsetting fig. 7.6/7/8/9 scan
  • Gross to net explosion tells us how many of each
    component are needed for a finished product.
  • The WHEN they are needed is the Lead Time Offset

Planning Horizon fig. 7.8/9
  • It should be estimated by calculating the
    cumulative lead time for the products made in the

Allocationand Availability Checking (fig. 7.8
pp. 241-242 picking tickets)
  • Prior to order launching, an availability check
    should be done for the necessary components.
  • If not all available a partial order could be
    evaluated in conjunction with marketing.
  • After this a picking ticket should be issued so
    that items are removed from their physical

Actions of the MRP Planner
  • Release orders to shop or vendors. Closing that
    orders occurs when scheduled receipt are received
    into stockrooms. Then a transaction must be
    processed to increase the on-hand inventory and
    eliminate the scheduled receipt.
  • Reschedule due dates pp. 242-243
  • Analyze and update system planning factors for
    the part numbers under her control
  • Reconcile errors and inconsistencies
  • Find key problem areas
  • Use the system to solve critical material
  • Indicate where enhancements would make job easier.

System Dynamics
  • It is essential that the MRP system mirrors
    actual shop conditions, that is the information
    system should have to cope with scrap, incorrect
    counts, changes in customer needs, incorrect BOM,
    engineering design changes, etc.
  • Figures 7.10, 11 and 12 pp. 244-247 cioè, se un
    ordine viene cancellato bisogna propagere la
    cancellazione a tutti I livelli inferiori della
    BOM altrimenti viene inutilmente impegnata la
    capacità produttiva!

Complex transaction processing
  • The situations that are faced by the MRP planner
    tend to be more complex than described in the
  • An example is Fig. 7.13 pp. 247-259

Poi ripresentare da V.Nicolò MRP pp. 85gt96 La
pianificazione della capacità pp. 97gt100 PAC -
Production Activity Control pp.
102-103 Articolazione della pianificazione della
produzione La misura delle prestazioni Il modello
di riferimento dellattività produttiva Tipi di
processi operativi Supply Chain