material requirements planning Flashcards
Material requirements planning (MRP)
the logic for determining the number of parts, components, and materials needed to produce a product
MRP is a logical, easily understandable approach to the problem of determining the number of parts, components and materials needed to produce each end item. MRP also provides the schedule specifying when each of htese items should be ordered and produced
MRP is based on dependent demand. Dependent demand is caused by the demand for a higher level item
Master production scheduling
generallly, the master production schedule deals with end items and is a major input to the MRP process. IF the end item is quite large or quite expensive, however, the master schedule may schedule major subaseemblies or components instead
To ensure good master scheduling, the master scheduler (the human being) must:
include all demands from product sales, warehouse replenishment, spares and interplant requirements
never lose sight of the aggregate plan
Be involved with customer order promising
Be visible to all levels of management
Objectively trade off manufacturing, marketing and engineering conflicts
Master production schedule (MPS)
a time phased plan specifying how many and when the firm plans to build each item
Time fences
periods of having some specified level of opportunity for the customer to make changes
E.g. are frozen (no change), slushy, liquid (change allowed)
Available to promise
a feature of MRP systems that identifies the difference between the number of units currently included in the master schedule and the actual (firm) customer orders
kBill of materials
the complete product description, listing the materials, parts and ocmponents, and also the sequence in which the product is created
Modular bill of materials
the term for a buildable item that can be produced and stocked as subassembly. It is also a standard item with no options within the module
Super bill
of materials includes items with fractional options
Low level coding
placing all identical items at the same level
Inventory records
The MRP program accesses the status segment of the record according to specific time periods. Theres records are accesssed as needed during program run
Net change system
an MRP system that calculates the impact of a change in the MRP data
Four lot sizing techniques
Lot for lot
Economic order quantity
least total cost
least unit cost
Lot sizes
the part quanitties issued in the planned order receipt and planned order release sections of an MRP schedule
Lot for lot (most common technique)
Sets planned order to exactly match the net requirements
Produces exactly what is needed each week with no inventory carried over into future periods
Minimizes carrying costs
Does not take into account setup costs or capacity limitations
Economic order quantity
An EOQ model eiher fairly constant demand must exist or safety stock must be kept to provide for demand variabliilty
Qopt = sqr(2ds/h)
least unit cost method
is a dynamic lot sizing technique that calculates the order quantity by comparing the carrying cost and the setup (or ordering) cost for various lot sizes and then selects the lot in which thesea re most near equal
Least unit cost
the least unit cost method is a dynamic lot sizing technique that adds ordering and inventory carrying cost for each trial lot size and divides the number of units in each lot size, picking the lot size with the lowest unit cost
Choosing the best lot size
the advantage of the least unit cost method is that it is a more complete analysis and wuld take into account ordering or setup costs that might change as the order siize increases. If the ordering or setup costs remain constant, the lowest total cost method is more attractive because it is simpler and easier to cmopute yet it would be just as accurate under that restriction
