Alternate materials

In many industries the bill of materials can contain alternate materials: the same product can be produced using different components.

FrePPLe provides 2 constructs to model such alternatives:

  • A first option is to use different operations, all producing the same item. Each alternate operation operation can use a completely different set of materials and resources.
  • A second option is to model an alternate for a single consumed item. A single operation is used and one of its operation-materials can be substituted with another.

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The example models shows both modeling constructs:

  • Alternate operations
    The product X can be produced using 2 versions of the bill of materials, modeled as different operations. Version 1 uses components A, B and C. Version 2 uses components C, D and E.
    The operation table has 2 operations to produce the item X. The fields priority, search mode, effective start date and effective end date control which alternate is selected when generating the plan.
    In this example there is a short period of time where both versions of the bill of materials are effective. During this time period the planning algorithm will select the cheapest production mode - which is the second bill of material that uses cheaper components.
    Operation table
    The generated plan has manufacturing orders on both operations.
    Manufacturing orders
  • Alternate item
    The component C can be substituted by component C-alt in both versions of the bill of material. Component C-alt is preferred over C, but it has a longer lead time.
    The operation material table contains records to consume both component C and C-alt. The name field is used to mark that these records are alternates of each other. The fields priority, search mode, effective start date and effective end date control which of the substitutes is selected when generating the plan.
    Operation material table
    In the generated plan you’ll see that the preferred component C-alt is purchased after its long lead time. Until then we need to buy component C to meet our demand.
    In the inventory detail report you can review the inventory changes of all items. You can see that manufacturing order 5 for operation “Make X version 2” uses item C, while the manufacturing order 6 uses item C-alt.
    Inventory detail for C and C-alt