IMM 8th ed Ch 3

Chapter 3: Master Scheduling Overview

  • This chapter discusses the components and significance of master scheduling in materials management.

Key Concepts in Master Scheduling

Relationship to Production Plan

  • Master Schedule (MPS): Acts as the formal link between production planning and execution.

  • Production Plan: Initiates the monthly data that informs the master scheduling process, addressing whether to pursue a level or chase strategy.

Types of Scheduling

  • Forward Scheduling: Prioritizes equipment efficiency, focusing on the development of a master schedule while modifying for inventory levels.

  • Backward Scheduling: Involves scheduling based on inventory key, where production starts from the end date and works backwards.

Rough Cut Capacity Planning (RCCP)

  • Evaluates the availability of critical resources including bottleneck operations and necessary labor/material resources.

Rating Plans

  • Ratings are primarily used for assessing resource utilization, customer service, and cost.

  • Different production strategies include:

    • Make-to-Stock (MTS)

    • Assemble-to-Order (ATO)

    • Make-to-Order (MTO)

    • Configure-to-Order (CTO)

    • Engineer-to-Order (ETO)

Key Objectives of Master Production Schedule (MPS)

  • Customer Service: Ensuring that products are available to meet customer demand.

  • Resource Efficiency: Utilizing resources effectively while maintaining inventory levels.

  • Steps to accomplish these objectives include:

    • Developing a preliminary MPS.

    • Checking the MPS against capacity and resource availability.

    • Reconciling any discrepancies.

Planning Horizon and Time Fences

Planning Horizon

  • The minimum time span needed for the MPS, calculated as the longest end-to-end lead time in the product structure.

Time Fences

  • Defined as specific points in the planning horizon to determine MPS flexibility:

    • Frozen Zone: Closest to the current date; orders cannot be changed without management approval.

    • Slushy Zone: Less commitment to materials, allowing some trade-offs.

    • Liquid Zone: All changes are permissible within production plan limits.

Available to Promise (ATP)

  • Calculation of ATP focuses on customer orders, ignoring forecasts and safety stock.

  • ATP is influenced by scheduled receipts and backlog, adjusting for any periods where demand exceeds MPS.

Changes to the Master Schedule

  • Recognizes that changes are often unavoidable; however, all adjustments should be monitored closely due to potential ripple effects through the production system.

  • Encourages leveraging 'what-if' analysis to preemptively identify issues.