MM / P2Padvanced

MM MRP Part 4: Planning Time Fence, Firming and Procurement Proposals

Key takeaway

Stabilize near-term plans: firming of planned orders and requisitions (manual or by planning time fence), MRP types for time fences, creation indicators for PRs vs planned orders vs schedule lines, conversion of proposals, and how firming interacts with MRP runs.

Explanation

📌 KEY POINTS
✅ Firmed proposals are not changed or deleted by MRP.
✅ Manual changes firm a proposal; the planning time fence can firm automatically (MRP types P1–P4 with firming types).
✅ Creation indicators decide whether external requirements become PRs or planned orders, and whether schedule lines are created.
✅ Inside the time fence, MRP may create proposals at the fence end instead of changing firmed ones.
⚠️ Too many firmed proposals freeze the plan and hide real changes.

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▶ WHERE WE ARE
Part 3 covered parameters. Now stability.

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▶ 1. FIRMING

Manual change or firming flag; effect on MRP.

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▶ 2. PLANNING TIME FENCE

Days defined in MRP view; MRP types P1–P4 with different firming behaviors.

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▶ 3. CREATION INDICATORS

PR vs planned order, schedule lines for scheduling agreements.

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▶ 4. CONVERSION

Planned order → PR (external) or production order (in-house).

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▶ 5. PLANNER ACTIONS

Exception messages to adjust firmed proposals manually.

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▶ STEP BY STEP

Set planning time fence 10 days and MRP type P1.
Increase requirement inside the fence; run MRP.
Observe how MRP handles firmed proposals.

✅ CHECKPOINT: near-term proposals remain stable while later ones adapt.

Code example

ABAP Code

===== STEP 1: settings =====MRP1: MRP type P1 (firming within time fence) | MRP2: planning time fence 10 days ===== STEP 2: behavior =====Firmed proposals inside fence unchanged | new requirement → proposal at end of fence + exception message ===== STEP 3: creation indicators =====MD01N: PRs for external procurement | schedule lines for scheduling agreements (source list MRP relevance 2)

Real project scenario

A demand spike moved requirements earlier, but a planner saw no new proposals because all near-term PRs were firmed by manual edits. MRP only issued reschedule-in messages that nobody processed. Training planners on exception messages and limiting manual edits restored responsiveness.

Common mistakes

Firming everything.
Ignoring exception messages.
Wrong creation indicators.
Time fence too long.
Manual edits as routine.

Best practices

Firm deliberately.
Process exception messages daily.
Choose time fence per material.
Set creation indicators consistently.
Review firmed proposals.

Interview angle

Questions: "What is firming?", "What is the planning time fence?", "What do creation indicators control?"
Strong answer: firming effects, time fence with P-types, creation indicators, conversions, exception handling.

Practice this lesson

Quick check

1. Requirements moved earlier but no new proposals appeared because near-term PRs were firmed. How does MRP react to firmed proposals?

2. What happens to a purchase requisition that a planner changes manually?

3. Which setting decides whether MRP creates purchase requisitions or planned orders for external procurement?

Interview questions

1. Suppliers complain that requisitions and schedule lines change daily in the near term. How do you stabilize the plan?

Answer it in your own words first, then compare.

2. What are the most important design decisions, trade-offs, and best practices in Material Requirements Planning?