## 2 Methodology, Fundamentals, and Materials
### Optimization Alternatives: Improvement Strategies and New Technologies  
Nowadays, there is significant pressure on organizations to improve customer satisfaction and quality levels, and at the same time to decrease ineffectiveness and reduce the number of errors. Organizations need to gain and retain customers, as they are the key elements that drive the economy. There are many different conceptions, methods and tools that may be used to maintain a good quality level and help in the continuous development of a company [26]. For this purpose, and as a result of more than 60 years of the study of production systems, Toyota has developed a range of methodologies and tools that have been tested around the world by companies of all sizes and sectors, obtaining huge improvements in all of their processes and equally significant reductions in production costs [27]. From this development, other strategies have added conceptual and practical frameworks in order to achieve strategic improvement. Some of the most relevant strategies are presented below:  
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* Lean manufacturing (LM): Lean manufacturing arose from the Toyota Production System and is described as manufacturing without waste [28]. Six Sigma (SS): After the inception of TQM in the early 1980s, Six Sigma emerged as an element of TQM that could be seen as the current state of evolution in quality management. Six Sigma is a strategy that helps to identify and eliminate the defects which lead to customer dissatisfaction in tire industries [29]. * Theory of constraints (TOC): [PERSON] (1990) declares that \"any system in reality must have at least one constraint\". In the case of chains, the strength of the whole chain equals the strength of the weakest link. Similarly, in the case of organizations' performance, the final throughput of a company is limited by the resource with the lowest capacity [5]. * Quick response manufacturing (QRM): Based on time-based competition (TBC), QRM is a companywide strategy in which the main focus is to reduce the lead time [28]. * Agile manufacturing (AM): Agile manufacturing is a responsive manufacturing strategy with the goal to survive in continuously and unpredictably changing environments as it focuses on fast response throughout the supply chain to mitigate the effects of variability [30]. [PERSON] and [PERSON] (2021) developed a systematic improvement model for the integration of relevant improvement strategies for the design and optimization of manufacturing organizations [31]. This model considers the most relevant strategies described before and it is used as basic framework to study the integration of improvement strategies and the Industry 4.0 related technologies studied in this research paper. Moreover, a survey of 200 manufacturing companies demonstrates how lean strategy is also pursued together with the implementing of Industry 4.0 solutions, although this study also showed how managers are concerned with making new technologies compatible with the dynamism of lean environments [32]. Industry 4.0 consists of several vaguely defined and partly overlapping technologies [33]. Both lean production and Industry 4.0 favor decentralized structures over large, complex machines and both aim for small modules with a low level of complexity [8]. As described in the previous chapter, the integration of Industry 4.0 solutions matches lean philosophy and the mentioned examples proved feasibility. Industry 4.0 can be integrated in lean production and, beyond that, can improve lean production with increased integration of ICT. Applying Industry 4.0 to established lean production could lower the risks of integration due to existing advice for organizational integration. Additionally, production processes in lean production are, in comparison to other kinds of organizations, more standardized, more transparent and reduced to essential work. As a result, they are less complex and support the installation of Industry 4.0 solutions [8]. Companies indicate standardization as a highly important precondition.