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Advanced Planning and Scheduling

APS (advanced planning & scheduling, enhanced planning) — the system for constructing a per-minute schedule of equipment operation throughout the entire production, taking into account a variety of business criteria and the integration of production into the supply chain.

APS plan is formed taking into account the limitations imposed by the permissible capacity utilization, the actual and predictable availability of materials and other production resources. As a result, detailed operational production plans are obtained for each work center with the optimal sequence of work.

The system is based on a serious mathematical base

The mathematical basis of APS planning in IT-Enterprise system is the theory of schedules - a special section of mathematical programming and operations research, which deals with the tasks of constructing optimal work sequences (schedules) at the work centers allocated for this subject including various constraints. Since universal mathematical optimization algorithms are non- polynimial solvable (NP-difficult from a computational point of view), the mathematical basis for scheduling in IT-Enterprise is the combined use of various heuristic and optimal scheduling theory algorithms.

Prerequisites for the transition of the enterprise from volume planning to APS planning

• The lack of a reserve of free capacity or the level of capacity utilization of more than 60-70%, two-three-shift operation of the main workshops
• The presence in the production of “bottlenecks” - working centers with a shortage of capacity
• The need to optimize intra-day production processes
• Duration of key operations performance more than a shift (day)
• Low determinism of the process (several days ahead)
• Large range of products and semi-finished products
• High degree of readiness of information on technological processes, stock status, MPS- and MRP-planning schemes used at the enterprise

Plan optimization criteria

IT-Enterprise system supports various models, methods and planning sequences, the combination of which determines the specific implementation of optimization planning in the enterprise.

The formation of APS/MES-plan is performed according to the following optimization criteria:

• Commercial optimization criteria. Minimization of violations of the terms of shipment of orders agreed with clients (minimizing the time spent in the production of orders, maximizing customer service ratio, etc.)
• Production optimization criteria. Maximizing capacity utilization (minimizing changeovers and downtime, maximizing the rhythm of production, etc.)
• Other optimization criteria, including optimization by several criteria simultaneously. In this case, the criteria are ranked by priority

Commercial and production optimization criteria are contradictory. Therefore, based on the strategy of the enterprise in a particular market situation, either the commercial or production criterion becomes the main one.