WORK-IN-PROCESS (WIP) INVENTORY

2012 ◽  
Vol 10 (4) ◽  
pp. 217 ◽  
Author(s):  
Terrence J. Moran ◽  
John Stevens

The Setup time variable was evaluated for the two systems (Kanban and EPQ) against the performance measure of average WIP inventory cost. EPQ outperforms Kanban on average WIP inventory cost at setup times less than 8 minutes. The research helped clarify for practitioners whether EPQ might be more suitable than Kanban for their given situations.


2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Jingjing Jiang ◽  
Suk-Chul Rim

It is vital for make-to-order manufacturers to shorten the lead time to meet the customers’ requirements. Holding work-in-process (WIP) inventory at more stations can reduce the lead time, but it also brings about higher inventory holding cost. Therefore, it is important to seek out the optimal set of stations to hold WIP inventory to minimize the total inventory holding cost, while meeting the required due date for the final product at the same time. Since the problem with deterministic processing times at the stations has been addressed, as a natural extension, in this study, we address the problem with stochastic processing times, which is more realistic in the manufacturing environment. Assuming that the processing times follow normal distributions, we propose a solution procedure using genetic algorithm.


2014 ◽  
Vol 621 ◽  
pp. 201-208
Author(s):  
Dun Bing Tang ◽  
Hai Tao Zhang ◽  
Min Dai ◽  
Chang Sheng Wang

With the developing control and configuration pattern of modern manufacturing system, the complexity of manufacturing system is enlarged and the operating environment is filled with uncertainty. Under the influence of many uncertain factors, reducing delivery time, due-date performance and low inventory become the important goals of production enterprise. This paper presents a bio-inspired manufacturing system control model, combining the knowledge of manufacturing system, biological control and control system. The relationship between response time and production rate of manufacturing system with different capacity is analyzed, production capacity controller is designed using PI and PD, and the control strategy differences of production rate deviation and overshoot is also discussed. Finally, an optimized design for the parameters of a two-layer work-in-process (WIP) inventory controller is analyzed, with the reference to the neuroendocrine regulatory mechanism. The simulation analysis shows that in bio-inspired manufacturing system made of organic manufacturing cells, the shorter the response time of production capacity is, the faster its production rate responses. With the combination of two-layer WIP inventory controller and traditional PID production capacity controller, the production system is more responsive and the production offset and overshoot are small when the unexpected external demand changes of manufacturing system occur.


Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1029
Author(s):  
Ying-Mei Tu

Since last decade, the cluster tool has been mainstream in modern semiconductor manufacturing factories. In general, the cluster tool occupies 60% to 70% of production machines for advanced technology factories. The most characteristic feature of this kind of equipment is to integrate the relevant processes into one single machine to reduce wafer transportation time and prevent wafer contaminations as well. Nevertheless, cluster tools also increase the difficulty of production planning significantly, particularly for shop floor control due to complicated machine configurations. The main objective of this study is to propose a short-term scheduling model. The noteworthy goal of scheduling is to maximize the throughput within time constraints. There are two modules included in this scheduling model—arrival time estimation and short-term scheduling. The concept of the dynamic cycle time of the product’s step is applied to estimate the arrival time of the work in process (WIP) in front of machine. Furthermore, in order to avoid violating the time constraint of the WIP, an algorithm to calculate the latest time of the WIP to process on the machine is developed. Based on the latest process time of the WIP and the combination efficiency table, the production schedule of the cluster tools can be re-arranged to fulfill the production goal. The scheduling process will be renewed every three hours to make sure of the effectiveness and good performance of the schedule.


2019 ◽  
Vol 109 (03) ◽  
pp. 189-193
Author(s):  
A. Keller ◽  
S. Adler ◽  
N. Zobel

Im Forschungsprojekt „CPPSProcessAssist“ wurde für vier kleine und mittlere Unternehmen (KMU) der Prozessindustrie ein modulares und mobiles Assistenzsystem zur Instandhaltungsunterstützung entwickelt. Neben der technologischen Entwicklung des Systems wurde im Projekt eine Vorgehensweise zur Gestaltung und Einführung des Systems in den Unternehmen erarbeitet. Mitarbeiter der Schicht und Schichtleitung, Projektingenieure, Instandhalter sowie Technologieentwickler wurden als Mitgestalter des Systems und der daraus folgenden Veränderungen im Unternehmen eingebunden. Das resultierende System bildet die unternehmensübergreifenden Anforderungen von Instandhaltungsaufgaben in der Prozessindustrie technisch ab und ist an vorhandene IT-Infrastrukturen anpassbar. Die gewählte Vorgehensweise zur Einbindung der Mitarbeiter in der Gestaltung des Systems trug dazu bei, die unternehmens- und nutzerspezifischen Anforderungen in das System zu integrieren sowie die Mitarbeiter zu Eingabe bedarfsgerechter Assistenzinhalten zu befähigen.   A modular and portable maintenance assistance system was developed for four small and medium-sized process manufacturers in the research project CPPSProcessAssist. Along with the technological development of the system, a procedure for designing and implementing the system in the companies was developed. Shift workers and managers, project engineers, maintenance engineers and technology developers were involved in designing the system and implementing the ensuing changes in their companies. The resulting system technically maps cross-company requirements for maintenance work in process manufacturing and can be modified for existing IT infrastructures. The selected procedure for involving employees in the system design helped integrating specific company and user requirements in the system and enabling employees to enter content in the assistance system based on their needs.


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