PRODUCTION SCHEDULING WITH CAPACITY-LOT SIZE AND SEQUENCE CONSIDERATION

Abstract

The General Lotsizing and Scheduling Problem (GLSP) is a method of addressing a common problem found in continuous production planning. The problem involves many constraints including machine capacity, production lot-size, and production sequence. This study proposes a re-formulation of the GLSP divided into two phases known as the General Lotsizing and Scheduling Problem using Two Phases with External Supply (GLSP-TE). Phase one is the Pattern generation with Specific Batch size and Capacity. Phase two is the Production Allocation using Specified Pattern obtained from the production pattern in Phase One. Additionally, external supplies are included in the formulation to reflect the real situation for businesses faced with limited resources. In this study, the justification of the formulation is based on the ability to solve problems and calculation time. The proposed formulation was tested in eight scenarios. The results show that the proposed formulation is more tractable and is better at solving problems than the GLSP. The objective value of GLSP-TE showed improvement up to 70% in high fluctuation scenarios compared to the original GLSP with a defined computational time limit.