## 1 Introduction  
Digitalization and Industry 4.0. (I 4.0) are the latest trends in industry, specifically in managing and controlling production. However, evidently, well known methodologies for production management and improvement of production processes such as lean manufacturing, six sigma etc. are still important. Thus, authors [1] point that the only technological adoption which is characteristic of I 4.0 will not lead to distinguished results. Lean manufacturing practices help in the installation of organizational habits and mindsets that favor systemic process improvements, supporting the design and control of manufacturers' operations management towards the fourth industrial revolution [1]. In addition, it is known that changes toward Industry 4.0 could be significant and any mistakes or skipped step could cause waste in the future [2]. It is obvious how lean manufacturing is still an important topic, both for research and practice. [PERSON], [PERSON] and [PERSON] define five basic lean principles:  
* Value;
* Value chain;
* Flow;
* Pull;* Perfection [3]. Pull principle is the most complex principle for the company to achieve, mainly because many preconditions need to be satisfied in order to start with implementing this principle. Pull emerged from one of the most known paradigms of Toyota Production System (TPS) and that is Just-in-Time. (JIT). The idea behind Just-in-Time is to deliver the product to the customer as close as possible to when the customer requires it. [PERSON] and [PERSON] state that the Kanban is misunderstood as a synonym for pull and JIT production, when Kanban is rather just one of the means for achieving pull thus, is itself a pull control mechanism [4]. Later other pull control mechanisms have emerged. The aim of this study was to research the influence of bottleneck on productivity with respect to different pull control mechanisms, in different production conditions defined by level of variations, number of pull control cards and processing time. The influence of lean manufacturing implementation on productivity is well described in literature [5; 6; 7; 8; 9]. Adoption of lean manufacturing results in an increase of productivity not just in production processes, but also in the design of a product. Hence, in [10], the case study of adopting lean in product design is presented and it is described that after adopting TPS principles the number of design cases undertaken by the design department increased [10]. However, how do pull control mechanisms affect productivity and how do they behave depending on whether that there is or there is not bottleneck in the process? [PERSON] [11] argue that production control mechanisms have a direct influence on delivery, and that is driven by production lead time and by the productivity. On the other hand, bottleneck detection in manufacturing is the key to improving production efficiency and stability in order to improve capacity and thus productivity. In [PERSON]'s work, [12], it is presented that some studies have found that simply increasing the number of Kanban cards (inventory level) cannot resolve bottleneck problems. [PERSON] [13], researched three mechanisms Kanban, Conwip and Hybrid Kanban/Conwip in terms of bottleneck, but only how it affects the production lead time. According to the relevant literature, the most widely used three control mechanisms are Kanban, Conwip and Hybrid Kanban/Conwip [14]. On the other hand, DBR mechanism was specially designed for processes with bottleneck [15]. There is a gap in research that might take into consideration multiple mechanisms in the context of the impact of bottlenecks on productivity. Therefore, the intention of this study was to answer the following research questions:  
* Q1: Does the bottleneck affect the efficiency of the pull control mechanism (PCM)?