## 1 Introduction  
In an increasingly competitive business environment, companies must evaluate their competitive stance concerning their counterparts. Distinctive market positioning must be accomplished by adding value to the product, eliminating waste, as well as improving productivity [1].  
Lean philosophy was developed to optimize resource utilization by minimizing inefficiencies. It has garnered heightened significance within the current setting of international industrial competition [2, 3]. The main objectives of the Lean philosophy in a company are cost reduction while upholding product/service quality, waste elimination, customer satisfaction, and the establishment of streamlined organizational efficiency and efficacy. Lean philosophy has progressively begun to be adopted by companies in search of greater efficiency in their performance [4]. While certain Small and Medium Enterprises (SMEs) acknowledge the operational advantages inherent in Lean practices and tools, it remains evident that the adoption of such techniques is constrained by the lack of information, unclear demonstrable outcomes, and the shortage of required human and financial resources [5]. Consequently, these SMEs fall short of realizing their full operational potential.  
Additionally, a gap was identified in the literature related to the tailored implementation of Lean philosophy, specifically to the optimization of vehicle seat upholstery maintenance and repair processes. Thus, this study considers the application of Lean toolsto optimize the activity of a Portuguese Small Enterprise (SE) in the upholstery industry. This SE recognizes in the Lean philosophy a suitable approach to increase efficiency in production processes, despite the restricted knowledge about this philosophy and its tools that are limited to collaborators on the medium management board. Thus, the importance of this case study lies in the possibility of helping this SE achieve its competitive potential through the optimization of its activities. For this purpose, Lean tools will be used to identify situations that overload the process with inefficiency and/or waste and rectify the problems identified. Henceforth, this study makes the following contributions:  
* The process improvement of the company under study--by using Lean tools, the company will increase its productivity; streamline its activity; and, ultimately, contribute to enhancing its competitiveness in its market.
* Show that SMEs can benefit in optimizing activities from the implementation of Lean philosophy and its tools.
* Complement the lack of studies of this nature in the upholstery industry, and the lack of studies on the optimization of the vehicle seat upholstery productive process through Lean tools.
* Provide the literature with ideas and solutions for common wastes and inefficiency in productive processes, developed with Lean tools and Excel, which can be adapted according to each situation.
* For this purpose, this article starts with a literature review that allows a proper knowledge of the Lean tools most suitable for this purpose. Next, the case study is presented. An initial survey of the operations is described. Afterward, we present a section dedicated to each Improvement Opportunity (IO) identified in the company's activity. The results of the implementation of Lean tools are presented and discussed. Finally, some limitations and proposals for future works are detailed and a conclusion is presented.