POLC-A: an assessment of POLCA’s authorization element

Thürer, Matthias; Fernandes, Nuno O.; Stevenson, Mark; Silva, Cristóvão; Silva, Sílvio Carmo

doi:10.1007/s10845-018-1402-2

Cited by 15 publications

(5 citation statements)

References 33 publications

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“…POLCA's card allocation and dispatching element is discussed in Section 2.2.2. Note that we do not model POLCA's authorization element, which would restrict the number of eligible jobs at a station to jobs for which an earliest release date has been reached, given its direct detrimental impact on performance in Thürer et al (2019). The cardallocation decision is therefore executed continuously whenever a card becomes available (for the separated decision) or whenever an operation is complete (for the integrated decision), and all jobs in the queue are considered.…”

Section: Polcamentioning

confidence: 99%

On the integration of card-allocation and dispatching decisions in POLCA systems: an assessment by simulation

Fernandes

Thürer

Stevenson

2021

Production Planning & Control

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POLCA is an important card-based control system for low volume, high variety production contexts. A job can only be produced at an upstream station if it has acquired a POLCA card that has returned from its downstream station. A common assumption in the POLCA literature is that cards are allocated to jobs as soon as they return to the upstream station. This dissects the queue in front of a station into jobs that have a card (and can be produced) and those that do not have a card (and cannot be produced). This artificially and prematurely constrains the dispatching decision, i.e., the decision concerning which job to produce next at a station. In response, this paper proposes integrating the card-allocation and dispatching decisions such that the allocation of POLCA cards to jobs is postponed until the dispatching decision is made.Simulation results demonstrate that this integrated approach does not improve performance under simple ERD dispatching, as is commonly applied in the POLCA literature. But when a more powerful rule is applied, percentage tardy and mean tardiness performance improve by more than 75% and 50%, respectively, for an integrated decision. Most importantly, results suggest that in production environments like the one considered in this study, the integrated approach dispenses with the use of POLCA altogether if a suitable priority rule is used.

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Section: Polcamentioning

confidence: 99%

On the integration of card-allocation and dispatching decisions in POLCA systems: an assessment by simulation

Fernandes

Thürer

Stevenson

2021

Production Planning & Control

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“…For example, a POLCA 1-2 card is used between Station 1 and Station 2. Which specific job to work on next is determined, for example, by earliest job release dates that are calculated by the MRP system for each station (Th€ urer et al 2019b).…”

Section: Polcamentioning

confidence: 99%

Material Flow Control in High‐Variety Make‐to‐Order Shops: Combining COBACABANA and POLCA

Thürer

Fernandes

Stevenson

2020

Production and Operations Management

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Material flow control mechanisms determine: (i) whether an order should be released onto the shop floor; and (ii) whether a station should be authorized to produce. Well‐known approaches include Kanban, Drum‐Buffer‐Rope (DBR), Constant Work‐in‐Process (ConWIP), Paired‐cell Overlapping Loops of Cards with Authorization (POLCA), Workload Control (WLC), and Control of Balance by Card Based Navigation (COBACABANA). The literature typically treats these approaches as competing, meaning studies argue for the superiority of one over another. However, a closer look reveals that existing mechanisms either focus on order release (ConWIP, DBR, WLC, and COBACABANA) or on production authorization (Kanban and POLCA). This study therefore calls for a paradigm shift and argues that the different mechanisms may play complementary rather than competing roles. Using simulation, we assess the performance of COBACABANA and POLCA in a high‐variety make‐to‐order shop, a type of shop arguably in most need of material flow control given the importance of throughput times and delivery time adherence. Results demonstrate that COBACABANA outperforms POLCA, but the simultaneous adoption of both control mechanisms outperforms the use of either one in isolation. More specifically, adding POLCA production authorization to COBACABANA order release enables the superfluous direct load to be further reduced, resulting in shop floor throughput time reductions of between 15% and 26% while further reducing the percentage tardy and mean tardiness by up to 14%. Compared to no material flow control, the new combined mechanism realizes a reduction of almost 50% in the percentage tardy and more than 30% in mean tardiness.

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“…Thürer et al (2018) highlighted that performance gains can be obtained: (i) by using different rules for card allocation and dispatching other than the earliest release date rule, typically applied in POLCA; and, (ii) by addition of a simple starvation avoidance mechanism. More recently, Thürer et al (2019) evaluated the effect of POLCA's authorization element, showing that this element has a direct detrimental effect on percentage tardy and mean tardiness performance.…”

Section: Review Of the Polca Literaturementioning

confidence: 99%

“…Jobs with a single operation, which are not controlled in the original POLCA system, just need to acquire a release card. The number of release cards restricts the number of jobs or the workload at gateway cells, depending on whether cards are unit-based or load-based, as in COBACABANA (Thürer et al, 2014(Thürer et al, , 2019. Like POLCA cards, release cards are not part number specific and, therefore, can be acquired by any job requiring processing at a specific gateway cell.…”

Section: Extending Polca With Centralized Job Releasementioning

confidence: 99%

“…POLCA uses authorization dates to define when a job should start at each cell. Thürer et al (2019) recently showed that authorization dates might have a direct detrimental effect on the percentage of tardy jobs and on the mean tardiness performance. They suggested that authorization dates may be used to signal the priority of jobs, and not to decide when a job should start.…”

Section: Card Acquisition and Dispatching Rulesmentioning

confidence: 99%

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