An innovative mathematical modelling approach with assembly line feedi̇ng based on the milk-run system

Increasingly competitive conditions in today's world have led to the widespread adoption of the lean production philosophy in both the manufacturing and service sectors. Lean production aims to eliminate unnecessary movements and transportation processes. This process is referred to as in-house logistics. In-house logistics, which may seem necessary, can be largely eliminated through proper planning, scheduling, and on-time production. When feeding the assembly lines, it is crucial for companies with line-type production to eliminate non-value-added tasks in the production systems and to produce at the lowest cost and with the least stock at the beginning of the line in a short time. This study examines the assembly lines in a factory that produces multiple types of freezers and the feeding of these lines. In this factory, which experiences an increasing variety of products with customer demands, material diversity is also quite high. In the scope of the study, it is understood that the unnecessary material transport problem is two-stage. In the first stage, materials are transported to the assembly lines from the raw material warehouse using forklifts or pallet jacks. There is a significant loss of time during transportation. This time loss negatively affects production. Additionally, it is necessary to transport materials to the assembly lines in sufficient quantities. Unplanned transportation of materials can lead to imbalances in the lines, resulting in working with more or less stock than required. Within this thesis, a mixed-integer mathematical model that takes into account the balancing of multi-product assembly lines and the feeding of the lines simultaneously has been proposed. The proposed model has been applied to the Kayseri Sersim company, which manufactures freezers. Keywords: Assembly line balancing, assembly line feeding, milk-run, multi-model line, mathematical model, lean production