Material Requirements Planning

1
Material Requirements Planning

• Chapter 7
• Vollmann, Berry, Whybark, Jacobs

2
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
  items.

3
Objective of MRP

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

4
MRP and MPC

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

5
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
  (SCHEDULED RECEIPTS)
• The current and projected inventory status at the
  end of period (PROJECTED AVAILABLE BALANCE)
• Planned dallo scheduler, si aggiungono ai
  receipts replenishment orders for the beginning
  of each period (PLANNED ORDER RELEASES)

6
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.

7
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

8
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

9
Planning Horizon fig. 7.8/9

• It should be estimated by calculating the
  cumulative lead time for the products made in the
  system.

10
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
  location.

11
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
  shortages
• Indicate where enhancements would make job easier.

12
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!

13
Complex transaction processing

• The situations that are faced by the MRP planner
  tend to be more complex than described in the
  book.
• 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