379. MPS

Master Production Schedule (MPS): the disaggregated version of aggregate planning. Specifies how many of each individual product to make in each week (or shorter bucket).

379.1. What it specifies

For each end-item $𝑖$ and time bucket $𝑡$ (typically weekly for 6–12 weeks ahead):

• Planned production quantity — how many units to start production of
• Scheduled receipts — orders already in process
• Projected on-hand inventory — running balance
• Available-to-promise (ATP) — quantity uncommitted, available for new orders

379.2. Time-phased records

A typical MPS row for product $𝑖$:

ATP at week $𝑡$ = production scheduled for that week minus already-committed customer orders.

379.3. How MPS relates to aggregate plan

The aggregate plan says “produce $𝑋$ units total in October.” The MPS distributes $𝑋$ across:

• Specific products (model A, B, C)
• Specific weeks (week 1, 2, 3, 4)

Constraint: ${\sum }_{𝑖}{\text{MPS}}_{𝑖,𝑡}\le$ capacity granted by aggregate plan for period containing $𝑡$.

379.4. Frozen / liquid / planning zones

The MPS is typically divided into three horizons:

• Frozen zone (week 1-2): no changes allowed; orders are firm, production committed
• Slushy / firm zone (week 3-4): changes require approval
• Liquid / planning zone (week 5-8+): can be re-planned freely as new demand information arrives

Frozen-zone duration matches production lead time — once you’ve started making it, you can’t easily change.

379.5. MPS feasibility: Rough-Cut Capacity Planning (RCCP)

Before committing to an MPS, check that capacity (workforce, machines, materials) is sufficient. See RCCP.

379.6. Feeding MRP

The MPS is the input to MRP, which explodes each MPS quantity into component requirements via the bill of materials.

379.7. Common pitfalls

• Schedule nervousness: small forecast changes ripple through MPS → MRP → vendor orders. Solution: stable frozen zone + change-control rules
• Optimistic MPS: planning to produce more than capacity allows. Solution: RCCP early
• Ignoring lead times: scheduling production for week $𝑡$ without checking material arrives by then

379.8. See also

• Aggregate Planning — feeds MPS
• MRP — fed by MPS
• RCCP — feasibility check
• DRP — distribution-side counterpart