The Effect of Job Similarity on Forgetting in Multi-Task Production

• Published in: Procedia manufacturing 2019, Vol.39, p.983-990
• Main Authors: Hoedt, Steven, Claeys, Arno, Schamp, Matthias, Ginste, Lauren Van De, Aghezzaf, El-Houssaine, Cottyn, Johannes
• Format: Article
• Language: English
• Subjects: cycle time prediction; forgetting; learning; manual assembly; mixed-model
• ISSN: 2351-9789; 2351-9789
• DOI: 10.1016/j.promfg.2020.01.390

For many decades, research has been done on the effect of learning and forgetting for manual assembly operations. Due to the evolution towards mass customization, cycle time prediction becomes more and more complex. The frequent change of tasks for an operator results in a rapid alternation between learning and forgetting periods, since the production of one model is causing a forgetting phase for another model. a new mathematical model for learning and forgetting is proposed to predict the future cycle time of an operator depending on the product mix of his actual assembly schedule. A main factor for this model is the job similarity between the task that is being learned and is being forgotten. In our experimental study the impact of job similarity onto the forgetting effect is measured. Two groups of operators were submitted to an equal time schedule, with other tasks to perform. At first, both groups were asked to perform the same main task. In the subsequent phase, they were submitted to different assembly tasks, each with another job similarity towards the main task, before again executing that main task. After a period of inactivity, the main task was assembled again by every subject. Results confirm that a higher job similarity results in a lower forgetting effect for the main task.