1,720,975 research outputs found
An enhanced loading model for the probabilistic workload control under workload imbalance
No full textLoad-oriented manufacturing control (LOMC), a well known probabilistic approach to workload control, is based on limiting and smoothing workload using one static parameter for each workcentre, called load limit (LL). The value of this parameter is set by the shop managers based on the planned lead time at each workcentre. In this paper the use of LL is shown to be inappropriate for the smoothing of workloads when the workload is not sufficiently balanced. We propose to enhance the LOMC model by introducing two sets of parameters:
(i) limiting parameters (LPs), that are statical parameters of the workcentres, set by the shop managers. LPs are used to limit the workload released to the shop;
(ii) smoothing parameters (SPs), that are dynamical parameters of the workcentres, computed as a function of their real workload. SPs are used to smooth the jobs workload over downstream workcentres.
A simulation model was used to compare the enhanced model, based on two parameters sets, with the traditional LOMC model, based on a single parameter set. The simulation runs were earned out with different conditions of due-date assignments, dispatching rules and production mix. The statistical analysis performed on experimental results confirmed that the enhanced model achieves significantly better due dates under unbalanced workload conditions
The impact of parameters setting in load oriented manufacturing control
No full textOne of the most successful Order Review and Release techniques proposed in literature in last years is Bechte's Load Oriented Manufacturing Control (LOMC). In order to use such a procedure, three types of parameters have to be set: a Load Limit for each workcentre, the Planning Period length and the Check Period, i.e. how long is the interval of time between two subsequent order releases.
Previous papers have examined the effects of a modification in the values of the load limits. In this paper we present experimental results about the effects of different values for both the planning period and the check period.
Both parameters have a great impact on shop performances and, most important, present an optimal value. The optimal check period value was found to depend on the average amount of time required by each manufacturing operation performed in the shop; quite the contrary, no explicit dependency has been found to date for the planning period's optimal value
The interaction between lean production and industry 4.0: Mapping the current state of literature and highlighting gaps
Full text linkLean Production (LP) was born with the intention of improving company’s performances from an organizational aspect. Recently, a new paradigm has emerged promising the same impact but from a technological point of view, that is the fourth industrial revolution (I4.0). The study of the interaction between those two paradigms has become the center of interest of the scientific world. Each of the attempts, done in that regard, tackled this broad and new subject from a different perspective. The article aims at mapping those attempts to identify the type of interaction between LP and I4.0, whether they are mutually exclusive or inclusive, exhibit synergism or conflict, and highlight the areas in which this interaction is not investigated yet. Design/methodology/approach: The study relies on a systematic literature review of peer-reviewed articles discussing both LP and I4.0. Even though the term “Industry 4.0” was born in 2011, the “smart factory” term spans over decades, henceforth no time limit was set, up until and including February 2019. A coding analysis of all papers is conducted to reach a theoretical narrative, following the methodology of Carl Auerbach and Louise Silverstein in their book entitled “An introduction to coding analysis: Qualitative data” in 2003. Findings: The expected outcome of the study is a map of existing literature addressing the interaction between LP and I4.0, and future research directions to be investigated. Research limitations: The literature search comes from two main databases: Scopus and ScienceDirect leaving out other databases and the review is subject to a qualitative coding analysis. Practical implications: The results of the study show the current state of the literature, the possible gaps to be investigated, and help practitioners understand how this interaction unfolds and how they can benefit from it
La programmazione di breve termine della produzione in sistemi Job-Shop basata sul controllo del carico: risultati di ricerca e nuovi sviluppi.
No full textSupply chain planning: a quantitative comparison between Lean and Info-Sharing models
Full text linkBoth practitioners and scientists recognise importance of supply chain planning (SCP) for improving supply chain (SC) effectiveness and efficiency. Although many SCP policies have been developed in past decades, the debate on the best SCP model is still an open issue. This article compares Lean and Info-Sharing approaches as SCP models, with the aim of allowing a better understanding of pros and cons of each of them and to identify under which condition Info-Sharing is better, and when, on the contrary, Lean is better. To complete this objective, a broad simulation study has been carried out. The results show that Lean Supply Chain Planning model leads to huge inventory saving but, on the other hand, it requires greater transportation efforts than information-sharing-based SCP model. These opposite outcomes do not clarify which models is more efficient but, a set of indexes has been developed in order to solve the gap created by these discordant indications. Managers can use the proposed indexes to position their supply chain in the proposed multi-dimensional space, and see whether info-sharing or Lean is the best for them. A few examples of the use of the set of indexes and the results of the research are presented at the end of the article
Comparison of order review and release techniques in a dynamic and uncertain job shop environment
No full textThis paper proposes a new methodological pattern to assess the effectiveness of Order Review and Release (ORR) techniques in a job shop environment. The standpoint for this new method lies in the following remarks: (i) comparisons among ORR models should be performed in dynamic and uncertain environments; (ii) ORR techniques robustness toward the shop uncertainty and perturbations should be considered; and (iii) ORR models should be compared by changing their features one at a time, instead of comparing completely different ORR techniques. Consistently, we present a comparison among three ORR models, previously developed in literature, aimed at investigating: (i) the impact of a dynamic and uncertain environment on the performances achieved; (ii) the robustness of these ORR models when facing some environmental perturbations, like the system workload, the mix imbalance, the machine unavailability and the processing time variability, that usually take place in real life job shops; and (iii) the overall effectiveness of the way workload is accounted for over time, since the models differentiate only by this item, while any other feature of the release mechanism is the same. Simulation results highlight that the performances of the ORR techniques tested depend on how perturbed the environment where they are implemented is. Moreover, the ORR techniques tested greatly differ in their robustness against environment perturbations
Workload Control in Job Shops through Order Review and Release Strategies: research issues and perspectives.
No full textComparison of Order Review and Release Techniques in a Dynamic and Uncertain Job Shop Environment
No full text- …
