BUS606: Operations and Supply Chain Management

 According to Andersen et al., in today's globalized production environment, changes are inevitable, and manufacturers must take advantage of either new technologies, changes in products or manufacturing processes. Paydar & Saidi-Mehrabad point out that for a company to survive, it is very important to meet the needs of customers, who demand products with high quality and lower prices. Continuous improvement of processes and products are key to have loyal customers and corporate survival.

Andrade & Fernandes point out the importance of integrating the stages of the production process through the interoperable integration since its planning. In this context, Mahdavi et al. mention that the use of process plans with pre-established alternatives can be advantageous, since a previously selected alternative resource can be included during the process plan elaboration. The presence of pre-planned alternatives can provide more flexibility in decision making.

In turn, Khilwani et al., Silva & Rentes , Defersha & Hodiya and Sieckmann et al. show that the appropriate choice of the shop floor layout is essential to enable and increase the competitiveness of a company in today's globalized economy.

In the context of a cellular manufacturing system, its advantages are: smaller batch sizes, reduction of work in process, and reduction of flow time. Ferreira & Reaes emphasize that both the reduction of flow and setup times, as well as the flexibility of the part routes, are very important characteristics for the viability of the business. Seeking to combine these two characteristics, the concept of virtual cells arises.

According to Mclean et al., a virtual cell is composed of machines from different departments that are associated logically during a certain time interval. Although physically arranged as in the job shop arrangement, the layout works as a traditional manufacturing cell. A virtual cell is not identifiable by a physical cluster, but by data files and processes within a production controller.

Dakov et al. and Rabbani et al. point out that VCMS (Virtual Cell Manufacturing Systems) were a first attempt at practical use for the concept of virtual cells. They mention as an important advantage of virtual cells over other layouts the almost unlimited adaptability to different production volumes without reducing the efficiency and effectiveness of the system.

Paydar & Saidi-mehrabad cite as an advantage of virtual cells the fact that the cellular arrangement occurs virtually, which is appropriate in the case of significant variations in the demand of parts, not being necessary the physical rearrangement of machines.

Ramachandran & Prasad cite the better performance of the virtual cell layout in different scenarios. It is worth mentioning the swiftness with which the system responds to demand changes.

For the analysis of different types of layouts and their effects on the production systems, different situations can be simulated. For Freitas Filho, simulation allows to understand the dynamics of a system, to analyze and to predict the effects of changes. Watanapa & Wiyaratn emphasize the importance of simulation, since it enables considering different scenarios to analyze the same problem. Mesquita et al. point out that the use of simulation assists in the anticipation of analyzes of real problems found in companies.

In turn, Kleijnen et al. state that design of experiments (DOE) assists the analysis of simulation results. In addition, DOE avoids the trial-and-error technique for finding solutions.

Based on the standard adopted by Mello, who did not consider the type of layout, he attempted to show that the use of alternatives provides advantages to manufacturing systems. Reaes presented a more comprehensive research, concluding that the virtual cellular layout performs better than traditional job shop and cellular layouts. However, Reaes did not consider in detail the design of products, limiting to 50 different types of parts. The parts in the present work were composed randomly, that is, a universe of features was stipulated, from which an infinite number of different products could be generated, trying to stimulate a scenario as close as possible to reality, where the market demands more and more flexibility, variety of product mix and shorter life cycles of products.

With regard to relevance, the results of the virtual cellular layout with a small number of resources, 21 in total, are highlighted, complementing the results found by Reaes, with 50 features, showing the applicability of the virtual cellular layout.

The choice of these three layouts was due to the virtual cellular layout linking the positive characteristics of both the job shop and the cellular layouts.

In this scenario, the objective of this paper is to compare the job shop, virtual cell and traditional cell layouts, identifying for which conditions each layout achieves better performance for different response variables.

Source: Claudio Decker Junior, João Carlos Espíndola Ferreira, Elisa Henning, and Carla Roberta Pereira, https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-65132019000100202
This work is licensed under a Creative Commons Attribution 4.0 License.