| Popis: |
The assembly job shop is a common shop type in make-to-order companies, which satisfies with the requirement of product assembly. Compared with deterministic scheduling, the majority of researches for dynamic assembly job shop focus on dispatching rules. However, most of researches do not consider the deterioration of machine. This study extends the assumption that machine is always available. Under the dynamic assembly job shop with breakdown and preventive maintenance (PM), researches are conducted as follows: (1) Three representative PM policies are compared; (2) The performance of classic dispatching rules for assembly job shop are compared. (3) From the view of constituent attributes of dispatching rules, we analyze the influence of machine maintenance on dispatching rules, and a new dispatching rule, MALLOPN (modified allowance per operations), is proposed. The full factorial simulation experiments are carried out with different levels of machine deterioration. The results show that the policy with optimal PM period (PM policy II) is the best one and the MALLOPN rule outperforms classic rules. |
