From Production Envelopes to Executable Schedules: Sound Constructive Refinement for High-Mix Manufacturing

TL;DR

This paper presents a sound constructive refinement framework for high-mix manufacturing, converting production plans into executable schedules while ensuring capacity, compatibility, and delivery constraints.

Contribution

It introduces a residual-invariant-based refinement method with a proven soundness theorem, implemented as an APS prototype for industrial manufacturing.

Findings

Achieves 100% on-time delivery in a real industrial case.

Eliminates outsourcing and bounds capacity loss to 1.9-4.6%.

Maintains robust delivery performance under demand and changeover perturbations.

Abstract

High-mix manufacturing systems require production plans that are both profitable and refinable into executable machine-level schedules under heterogeneous resources, mold-dependent compatibility, setup losses,delivery windows, and accessory synchronization. We study this problem as a production-envelope refinement task. A rolling-horizon mixed-integer linear programming (MILP) planner generates a valid production envelope that fixes daily production, fulfillment, mold states, inventory flows, outsourcing, and unmet-demand variables. A structure-aware constructive scheduler then refines this envelope into concrete order-machine allocations while preserving capacity feasibility, product-mold-machine compatibility, and delivery-window compliance. The scheduler enforces a one-mold-per-machine-per-day stability rule to avoid intra-day mold fragmentation. We establish residual invariants and prove a soundness theorem: whenever refinement terminates with zero residual fulfillment, the returned allocation is executable with respect to the valid envelope. The framework is implemented as an Advanced Planning and Scheduling (APS) prototype and evaluated on a real industrial case from a Jiangsu smartphone-case manufacturer in China with 37 product types, 150 orders, and over 8.3 million requested units. The proposed stable refinement achieves 100% on-time delivery, eliminates outsourcing, and bounds changeover-driven capacity loss to 1.9-4.6%. Across nine demand and changeover perturbation scenarios, it maintains robust delivery performance, showing that sound envelope refinement is a practical mechanism for reliable manufacturing scheduling.