Using the when/where rules in dual resource constrained systems for a hybrid push-pull control

Most shops in practice are constrained by more than one resource. Consequently, a large body of literature on dual resource constrained shops has emerged. This research typically focuses on worker assignment rules, with attention being on when and where to move workers. In contrast, the decision concerning who to reallocate to a station has received limited attention.The limited prior work assumes workers are assigned to a new station as soon as they become available or seeks to minimize the risk of worker idleness. Using simulation, we question this assumption and show that it can be beneficial to introduce additional worker idleness to ensure workers only work at their most efficient station(s). In general, it is less likely that there are several workers available for one station than it is for there to be multiple stations available for one worker. Consequently, the Who Rule is used less frequently than the Where rule and has less of an impact on performance. Finally, considering the criticality of work orders as part of the Where Rule is important in assembly shops; but if labor is heterogeneous then the focus should be on efficiency. The findings have important implications for research and practice.

Section: Introductionmentioning

confidence: 99%

Worker assignment in dual resource constrained assembly job shops with worker heterogeneity: an assessment by simulation

Thürer

Zhang

Stevenson

et al. 2019

“…on decisions concerning when to move workers to cope with a labor shortfall, where workers should be moved to, and who to move (e.g. Bobrowski & Park, 1993;Malhotra & Kher, 1994;Fredendall & Melnyk, 1996;Jensen 2000;Kher, 2000a;Kher & Fry, 2001;Bokhorst et al, 2004;Salum & Araz, 2009;Sammarco et al, 2014). In contrast, there is very limited research on the performance impact of order release control methods in DRC shops Fredendall et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

Workload control in dual-resource constrained high-variety shops: an assessment by simulation

Thürer

Stevenson

Renna

2018

Workload Control (WLC) seeks to align capacity with demand, where capacity is typically assumed to be restricted by a single constraintmachine capacity. In practice however, shops are often restricted by dual resource constraints: labor and machines. This study therefore uses simulation to investigate the performance of WLC in Dual Resource Constrained (DRC) highvariety shops with fully interchangeable labor. By considering several environmental factors and different labor assignment and dispatching rules, it is demonstrated that the order release function of WLC maintains its positive impact on performance in a DRC shop under different staffing levels. The positive effect of considering labor availability at release, as proposed in previous research, could not however be confirmed. Thus, the original release method can be applied if labor is fully interchangeable. In terms of labor assignment, we show that a distinct assignment pattern that differs between upstream and downstream stations improves performance if the routing is directed. Meanwhile, dispatching plays a less important role but creates important interaction effects with the assignment rule. Finally, the results suggest that increasing the service rate is a better response to the reduction in capacity that results from labor absenteeism than lowering the input frequency of work.

“…Researchers have studied a variety of 'Where' rules including: Random choice (RND); first come, first served (FCFS); first in system, first served (FISFS); shortest operation time (SOT). Several other variants based on due date, bottleneck and amount of load have also been implemented (Nelson 1967;Fryer 1973;Gunther 1979;Treleven and Elvers 1985;Treleven 1989;Park 1990;Hottenstein and Bowman 1998;Salum and Araz 2009). (2) 'When' rules: This rule indicates when the worker is available to move to another machine to process task.…”

Section: Drc Systemsmentioning

confidence: 98%

Agent-based modelling of movement rules in DRC systems for volume flexibility: human factors and technical performance

Sammarco

Fruggiero

Neumann

et al. 2013

This research applies Agent Based Modeling (ABM) to study volume flexibility in a Dual Resource Constrained (DRC) assembly flow shop environment. The simulation experiment evaluated System and Human Effects of varying DRC system staffing levels according to Design (i.e., Workforce, Distance and Buffer Capacity), Sensitivity (i.e., Coefficient of Variation) and Operating (i.e., When-rule and Where-rule) factors. Results showed that the rule by which workers are assigned to workstations affects WIP and Flow Time performances more than production rates. Furthermore per-worker productivity was found to increase, compared to the fully staffed system, particularly where the Downstream movement rule was applied. Using the Downstream rule when changing stations after completing current tasks reduced Flow Time (-15%) and WIP (-10%). If another Where-rule is chosen then it may be preferable for workers to move only after completing all jobs in the station (Decentralized rule). For Utilization rates and Mean hourly Switching of work (Human Effects), the model shows complex relationships depending on almost all evaluated factors. The novel ABM approach used here enabled the evaluation of emergent system behaviors and showed potential to help firms understand both human and performance effects of operational choices in efforts to achieve volume flexibility