Material requirements planning answers the question "what do we need?", but in its classical form, it assumes unlimited capacity . Capacity planning corrects this assumption: are there really machines and people to do the job?
Scope
Capacity supply is defined as the net capacity of each business center, derived from its calendar, shift, and utilization rates.
Capacity demand calculation: The load derived from planned and open work orders and route times.
Load profile: Comparison of supply and demand by source and period; visual representation of oversupply and gaps.
Bottleneck analysis: Identifying the source that restricts the entire flow. The main focus of planning is the bottleneck; high utilization rates in sources outside the bottleneck are not good, they create intermediate stock.
Capacity balancing methods: Shifting the work to another period, transferring it to an alternative work center, adding extra shifts, outsourcing, or rescheduling the order.
Finite capacity planning: Automatically generating a plan that does not exceed the capacity limit.
Scenario comparison: Comparing the alternatives of "if we add another shift," "if we activate this machine," and "if we outsource this product."
Long-term capacity plan: Investment decisions should be based on future load projections.
The practical result of the theory of constraints.
The output of a production system is determined by its slowest resource. This has three practical consequences:
1. An hour lost in a bottleneck is an hour lost for the entire system; it can never be recovered. 2. An improvement made in a non-bottleneck resource does not increase total output; it only creates intermediate inventory. 3. A bottleneck should never be left without material; there must be a planned buffer in front of it.
Therefore, the first task of capacity planning is not to try to balance all resources; it is to identify the bottleneck and protect against it .