Parallel Machine Scheduling with Shortest Processing Time (SPT) and Longest Processing Time (LPT) TO Minimize MAKESPAN at PT.ABC

Abstract

PT. ABC is a manufacturing company in the Garment sector. The problem faced by the company is to 
determine the production strategy to be able to fulfill orders from consumers. The production process that 
is the object of research is the production process on a washing machine. The washing process has two 
identical machines installed in parallel that will do 10 jobs. Scheduling by the company currently uses the 
First Come First Served method with a makespan of 2255.7 hours. The research provides an alternative 
method for scheduling with the Shortest Processing Time and Longest Processing Time methods. The 
scheduling process using the SPT method produces a makespan of 2070.06 hours, while scheduling using 
the LPT method produces a makespan of 2039.34 hours. The proposed method in this research results that 
the LPT method produces a better makespan than other methods. The makespan efficiency of this 
research shows a saving of 9.59%, which is 216.36 hours.