Lot Size Determination for Sequential Process Chains
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Solution Overview
Problem
In supply chain management, determining the maximum possible lotsize of products within a given time interval is challenging due to shared resources with limited availability, where each subsequent process step can only start after the previous one has finished, and resources are not continuously available.
Innovation Solution
A method to determine the maximum possible lotsize by calculating the largest number of process steps that can be performed within the available time intervals of each resource, considering serial dependence and resource availability, and iteratively optimizing by extending bottleneck intervals and accounting for breaks and startup times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resources are shared and availability is limited over time, then resource utilization efficiency is improved, but the complexity of scheduling process steps increases
Solution Approach 1:
The method segments the scheduling problem by determining availability intervals for each resource separately, then calculating the maximum lot size for each interval independently. This breaks down the complex scheduling problem into manageable segments that can be processed systematically.
Solution Approach 2:
The method performs preliminary actions by first determining the availability intervals for all resources before calculating the lot size. This preliminary scheduling of resource availability prevents conflicts and simplifies subsequent production planning.
2Manufacturing precision
If the maximum possible lotsize is determined through complex optimization, then production planning precision is improved, but computation time increases
Solution Approach 1:
The calculation is segmented into distinct steps: determining availability intervals, calculating unit times, and computing lot size. This segmentation allows for efficient computation at each stage rather than attempting a complex overall optimization.
Solution Approach 2:
The system uses its own output (availability intervals and unit times) to automatically determine the lot size without requiring external optimization algorithms. The method is self-contained and eliminates the need for complex iterative optimization processes.
3Reliability
If sequential dependence of process steps is enforced, then production reliability is improved, but flexibility in resource scheduling decreases
Solution Approach 1:
The method dynamically adjusts the lot size calculation based on the actual availability intervals of resources and the sequential process requirements. This allows the system to adapt to changing availability conditions while maintaining sequential integrity.
Solution Approach 2:
The calculation changes parameters such as availability intervals and unit times to determine the optimal lot size that satisfies sequential dependencies. By adjusting these parameters, the system maintains reliability while accommodating resource constraints.
Data Source
AI summary
The invention provides methods and apparatus, including computer program products, for of determining a possible lot size of units with respect to a fixed date for a chain of at least two process steps, each process step requiring a respective assigned resource, and consuming a respective time per unit for being performed by the respective assigned resource, where the process steps are sequentially dependent on each other. This is achieved by the following:(a) determining, for each resource, a respective time interval of availability during which the respective resource is continuously available, each time interval being limited by the fixed date,(b) calculating, for each determined time interval of availability, a respective largest possible number of times the respective process step can be performed by the respective resource, and(c) selecting the lot size of units to the minimum of the largest possible numbers.