Manufacturing cycle time reduction for batch production in a shared worker environment

Responsive delivery without inefficient excess inventory requires short manufacturing cycle times. The manufacturing cycle time is comprised of operation time, loading/unloading time, set up time and machine idle time. The sum of loading/unloading, set up and machine idle times is called downtime. To shorten batch processing time, reduction in downtime must be the first priority. One way to reduce downtime per work unit is to increase batch quantity, while another is to shorten the sum of set up and machine idle times. Whereas fast cycle time is critical for time-based competition, efficient utilisation of labour is also essential to keep a manufacturing company competitive due to the rapid increase in labour costs. Therefore, in many small and medium-sized businesses, one worker simultaneously handles multiple machines. In such a shared worker environment, machine idle time inevitably occurs due to a lack of available workers. The purpose of this paper is to propose a downtime reduction method based on part sequencing in a shared worker environment. The proposed heuristic results in a significant reduction in average downtime when compared to the results from the existing optimal sequencing method of independent machines.