A Case Study on the Multistage LED Packaging and Testing Scheduling Problem

Light-emitting diode (LED) industry will play an important role in the high-tech industry. At present, around the world promote energy-saving by reducing carbon. LED bulb could save more electricity than regular bulb, so the European Union from 2009 until 2012 will gradually replace energy-consuming bulbs and then be completely banned. A wide range of LED application, such as: the automotive industry, communications, information industry, with the signal display billboards and so on. LED industry is expected to be the next emerging industries. This study would focus on machine scheduling problem for LED packaging and testing factory. The light-emitting diodes packaging and testing scheduling problem (LEDPTSP) is a variation of the complex flow-shop scheduling problem, which is also a generalization of the classical flow batch process problem, and the identical parallel machine problem. In this paper, we present a case study on the LEDPTSP, which is taken from a final packaging and testing shop floor in an LED factory. For the LEDPTSP case investigated, the jobs are clustered by their product types, which are processed on groups of parallel machines at various process stages following the manufacturing sequence, which must be completed before the due dates. The job processing time depends on the product type, and the machine setup time is sequentially dependent on the orders of jobs processed. The objective in the case is to seek a LEDPTS with minimum total machine workload. The LEDPTSP involves serial-processing stage, job clusters, due dates, machine capacity, and sequence dependent setup time, it is more difficult to solve than the classical flow-shop scheduling problem. The LEDPTSP is formulated as in integer programming problem and the problem solved using the powerful CPLEX with effective implementation strategies.