**1. Introduction**

Industries need to be more competitive in order to survive in the increasingly dynamic and global environment. For this reason, they require different methodological approaches to make their operations more efficient. Some problems that block such operations' efficiency and disable the ability to respond to the environment, could be administrative, financial, or a production process, among others. In this article, we will focus on improving such a production process.

A process is any activity that occurs within the company [1] and, in this case, if there are problems in the processes, it is difficult to meet customer expectations in quality, delivery time, among others, which are qualities that are currently necessary. In addition, a process is a collection of activities that has one or more inputs and generates an output that adds value to the customer [2], which is also a process that could be seen as chains of activities and decisions [3]. According to Laguna and Marklund [4], the essence of process design is related to doing things in the "correct" way. Correct in this context refers to the process being efficient and effective. Efficiency refers to the fact that the customer's requirements must be met at the correct time.

For Davenport [2], business must be viewed in terms of redesigning the process from the beginning to the end using resources that are available in the company. Using resources that the company has is important for industries in emergent economies that do not have money to invest, and desire major improvements in quality, flexibility, service levels, or productivity [5]. In our context, a business problem is not adequately employing the resources that the organization has: machinery, equipment, facilities, etc., to achieve a response to the client in terms of time, quality, and service.

Being productive is related to different factors. Some of them are considered within this research work, since they were used precisely for the solution of the case study. Among them, there are adequate flows of the product, arrangements of the plant, and correct allocation of human-machine resources to the different activities that the process requires. Productivity can be defined as the number of outputs or finished products per unit of time [4,6]. Productivity can also be calculated by dividing item prices by their costs [7] and can be compared with past values from the same company for analysis. In this work, we will use the amount of production per unit of time, but we will use it to carry out analysis of different scenarios.

The main objective of this article is describing a case study carried out in an industrial shoe company in the state of Hidalgo, Mexico. In this company, there were productivity problems caused by the poor flow of the product. To deal with it, the reengineering phases were applied and, through these, a proposal was presented, which was analyzed through simulation. The study company did not want to be identified in this article so it will be called "the company" from now on, but the result of this intervention was implemented. This article presents the applied methodology and the results found this work could help other companies that have no idea how to identify and solve problems within their organizations.

The rest of the article is organized in the following sections. First is the literature review, which cites some works related to reengineering and simulation. Second, in Section 3, the materials and methods were described. The methodology is presented in Section 4 for Reengineering and Section 5 describes the simulation. In Section 6, the most important results are analyzed. Lastly, in Section 7, the conclusions of the work are given.

#### **2. Literature Review**

Before focusing on reengineering and simulation, it is necessary to mention other disciplines. Reengineering is not the only discipline that is concerned with improving the operational performance of organizations. Total Quality Management (TQM) preceded and inspired reengineering. The focus is on continuously improving and sustaining the quality of products while reengineering focus on the improvement of processes. Operations management is a field relevant to production and manufacturing. This area includes probability theory, queuing theory, mathematical modeling, Markov chains, and simulation techniques for improving the efficiency from this perspective. Operations management could be applied to existing processes and reengineering generates a new one. Another technique is lean manufacturing that pursue waste elimination for eliminating activities that did not add value to the customer such as using value stream mapping. Both reengineering and lean manufacturing have the customer orientation as a principle. Another technique is Six Sigma that focuses on minimizing errors and defects when measuring process output. Many Six Sigma techniques are applied in reengineering. All these techniques not only have similarities with reengineering, but can be combined with it [3,4].

The task arrangement and the excessive control of them are not the appropriate approach to achieve better production times within a productive organization [8]. There are now methodologies where the client plays the most important role and the service provided can be the difference between a company and its competition. It is for this reason that a small improvement fails to position companies, as the offer is extremely huge, and customers are increasingly selective when making purchases. Reengineering achieves dramatic enhancements through a complete redesign of core business processes, combined with rapid implementation, which makes it a strategy when significant changes need to be achieved. At this point, the definition of best fit is to "start again" [1]. According to Manganelli and Klein [9], reengineering is the answer when it is required to optimize workflows and productivity in an organization, as in the case presented in this study. Therefore, there are three types of improvement in the processes of organizations, which include a small improvement in one of the activities of the process, a redesign of the process, that involves changes in all operations, and reengineering, which is a radical redesign that destroys assumptions, builds again, and achieves dramatic changes in some performance measures [1,8].

For Hammer and Champy [1], reengineering is the fundamental revision and radical redesign of processes to achieve spectacular improvements in contemporary and critical measures of performance such as costs, quality, service, and speed. In this sense, it is always necessary to have measures of performance that provide clarity to know if the desired objective was accurate. Since the 1990s, when reengineering was first used, it has been successfully applied to different case studies. Ford, Mutual Benefit Life [8], Taco Bell [1], and others stand out. Hammer and Champy [1] considered a formal idea of what reengineering should be including the assumptions, what was expected in terms of achievement, and documented case studies. However, a formal methodology of how to achieve this was not detailed because reengineering must adapt to the particular situation of each company. As the years have passed, the concept has matured by applying it to different cases with significant results. Some of them are presented below.

Generally, Reengineering is combined with other methodologies because it is useful to analyze the root of the problems and present proposals for solutions based on its principles, but, to test if these proposals are adequate and implement them, it is necessary to use other tools. Nguyen [10] combines reengineering and lean manufacturing to improve an electronic assembly line by achieving a 40% decrease in the number of workers and 30% savings in production plant space. Other articles use basic tools but achieve significant changes. For example, with the application of reengineering to an air cargo handling company [11], flowcharts were used to analyze the number of activities, delays, etc. before and after applying reengineering, which achieves improvements in service. Reengineering and a balanced scorecard are used in the work of Turhan [12] where reengineering is applied to the supply chain. It is also used with a balanced scorecard in References [13,14] to make the diagnosis and present proposals to a bamboo panel construction company, which helps achieve improvements in the design of products, processes, and design of administrative activities.

Regardless of the number of companies involved in reengineering, the rate of failure in reengineering projects is more than 50 [1]. Some frequently mentioned problems related to reengineering include the inability to accurately predict the outcome of a radical change, and the inability to recognize the dynamic nature of the processes. Additionally, some publications argue that one major problem that contributes to the "failure" of reengineering projects is the lack of tools for evaluating the effects of designed solutions before implementation [15,16]. One way to do this is through simulation, since you have access to modify different input variables, while analyzing different parameters such as productivity, use of resources, along with others, and deciding on the best strategy. Simulation performance indicators are necessary to carry out the analysis [17]. The simulation also provides a graphical way of understanding the process flow, which is easily followed by the end user. It is possible to stop and modify and run again in such a way that each operation can be analyzed in a simple way [18].

Modeling through simulation is one of the most widely used techniques and can be considered a representation of a real system and in which it is experimented with the purpose of having a better understanding of its behavior and evaluating the impact of alternative strategies [19]. In today's dynamic environment, simulation helps us understand complex processes and can be used to make decisions within organizations [20].

There are many proven cases in the literature where reengineering and simulation have been used. Some of them related to production processes, Chen [21] applied reengineering to a construction company, where the traditional production is changed to a flow shop and the proposal is tested through simulation in Reference [22]. Reengineering and simulation are also combined to decrease bottleneck operations in a company that manufactures ceramic products by obtaining a 50% reduction in the time cycle and a reduction in delivery time from 3 to 1.5 days. Irani, Hulpic, and Giaglis [23] present the analysis in a production company, where reengineering was implemented using a simulation and innovation method to support decision-making. In a similar way, they have used both methodologies to service processes. See the works Sung [24] and Qiang et al. [25] in hospitals in which the first for improved surgical care and the second for hospital registration. Xiaoming and Xueqing [26] developed a framework for reengineering construction processes and corresponding methodologies that integrate lean principles and computer simulation techniques. Previous studies agree that simulation allows testing and analysis of different scenarios to understand their impact and assess feedback before moving forward with implementation plans.

Although other methodologies were analyzed when the intervention was being carried out in the organization, it was decided to use reengineering since it only requires simple activities such as training personnel. Another advantage is that human and economic resources that the company already has can be used, which makes it feasible. Moreover, the principles include destroying assumptions and starting again instead of not using technology without having analyzed if there are any problems in the process In addition to the numerous success stories in implementing it, they made it the ideal strategy to analyze the problem and issue a proposal. The simulation served to analyze this proposal with different scenarios before its implementation, as it is detailed in the next section. As a conclusion, there is no unique methodology for applying reengineering and sometimes it fails because it is not possible to test the effectiveness of the proposals made through reengineering, which is why we also address simulation. At the time the article was written, no references were found that used reengineering applied to an industrial footwear company.
