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CHAPTER IV Case of study: modellizzazione of one Manufacturing Supply Chain
4.14 To add the warehouse of the crude materials (Raw Materials Inventory).
Up to now the production rate begins them uguaglia always the production rate begins wished them,
implying that it revives like materials, job, and understood them they are always wide.
Figure 4,14 extension as the structure of the model can be corrected in order to include an explicit stock of crude materials or members.
Figure 4,14 - Structure of Materials Inventory The warehouse of the crude materials is modeled like one structure of management of the supplyes analogous to the warehouse of finished products.
The production can only begin if there is a sufficient supply of materials, and the company must order materials to sufficienza in order to maintain the warehouse to an appropriate level.
Production start installments is reformulated for to be equal to Feasible Production Starts from Materials (beginning of feasible production from the materials), the rate with which the production it can have beginning.
Material Usage Installments is the rate uses of the materials (materials/week) and Material Usage for Unit is the amount of materials demanded for outgoing unit of product (materials/widget):
- Production Start Installments = Feasible Production Starts from Materials
- Feasible Production Starts from Materials = Material Usage Installments Material Usage for Unit
Material Usage Installments is analogous to Shipment installments. It puts into effect them rate I use of the material is the rate I less use of the wished material (Desired Material Usage Installments) than the supply than material it is inadequate, case in which the rate I use falls under that one wished.
Material Usage Ratio is the fraction of the wished rate realized based on the adequacy of the warehouse of the materials.
Since the model combines many types of materials and members, usage ratio gradually comes down to of under of 100% as Maximum Material Usage installments (maximum rate I use of the material) falls under the rate I use wished:
- Material Usage Installments = Desired Material Usage Rate*Material Usage Ratio
- Material Usage Ratio =f (Maximum Material Usage installments Desired Material Usage Installments
The function that determines Material usage Ratio is analogous to the formulation for Order fulfilment Ratio. The rate wished of I use of the material is given from the wished beginning of production and from I use it of the material for unit:
- Desired Material Usage Rate=Desired Production Start Rate*Material Usage for Unit
The maximum rate with which the materials they can be used is determined from the running warehouse and the minimal time demanded in order to prepare and to deliver the materials to the production line.
This minimal cover of materials in warehouse depends on the system of management of the materials of the company and on the time of transport between the supply of materials and the production line.
- Maximum Material Usage installments = Materials Inventory/Minimum Material Inventory Coverage
The supply of materials is increased from the rate delivery of the materials (Material Delivery Installments) and diminished from the rate I use of the materials (Material Usage Installments):
- Materials Inventory=INTEGRAL (Material Delivery Installments Material Usage Installments, Materialst0)
- Material Delivery Rate=MAX (0, Desired Material Delivery Installments)
- Desired Material Delivery Rate= Desired Material Usage Rate+Adjustment for Material Inventory
- Adjustment for Material Inventory
Desired Material Inventory-Materials Inventory
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Material Inventory Adjustment Time
The warehouse of the materials wished is determined from the rate uses wished and from the cover of the warehouse of the materials wished, that, in the same way of the warehouse of the finished products it is set up like the sum of the minimal cover demanded and an emergency supply in order to assure that the supplyes do not obligate the beginning of the production under normal circumstances:
- Desired material Inventory=Desired Material Usage Rate*Desired Material Inventory Coverage
- Desired Material Inventory Coverage=Minimum Material Inventory Coverage+Material Safety Coverage Stock
In order to facilitate the analysis of the model, and without perdeta of generality, the simulation asume Material Usage for Unit=1 material unit/widget. Minimum Materials Inventory Coverage is 1 week (1 week) and Safety Coverage Stock is assumed anch'esso equal to 1 week. Material Inventory Adjustment Time is set up to 2 week.
The function that determines Material Usage Ratio is the same one used for shipments from the final warehouse.
Figure 4,15 extension the answer of the model to an unexpected increment of 20% of the orders.
Figure 4,15 - Answer of the warehouse of the materials to an unexpected increment of 20% in the question. Given to the parameters and the task increment of the question, the warehouse of the materials does not bring constrictions to the departure production. For which production starts uguaglia always desired start installments and the behavior of all the variable ones of the model is the same one of the diagrams of figure 4,13 (this cannot be true for one great variation of question).