The main purpose of the article was the reduction of the machine changeover time in practical terms, on the example of a forming machine in the production process of a trunk shelf, based on the use of the SMED method. The article presented the stages of development and the foundations of the lean management concept. The description of the SMED methodology was made. A forming machine was selected in the manufacturing process of a trunk shelf. The identification and measurement of changeover times in the real model were performed. Two alternative models were proposed. The first of them was made based on the division of activities into external and internal, and the delegation of external activities to be performed by the production staff. The second alternative model included investments. The proposed and implemented improvement actions brought benefits in a reduction of the changeover time of the tested machine.
TopIntroduction
The current economic crisis yielded by the worldwide crisis pulls on the corporation's pursuit of solutions extending effectiveness and performance of processes, among them production processes. In practice, multiple enterprises decide to implement the solutions based on the Lean Management philosophy. These answers allow the elimination of waste in various areas of the enterprise's functioning. Concerning the production companies and production processes, the losses relate to e.g. overproduction, downtime, machine losses, keeping the unnecessary inventory, or long-term research of the tools and machines.
The beginnings of the Lean Management conception can be dated to the times after the Second World War. This notion was initiated in the automotive industry in Japan. Its forerunner is the Toyota company, which began not only the new mode of action but also thinking (Dekier, 2012; Liker, 2004; Liker & Meier, 2006; Spear, 2004). The Lean Management conception was an answer to the present at that time issues in the market. The main concerns of the Japanese automotive market then were (Dave, 2020; Liker & Convis, 2012): the small size of the market, market demands requiring the offer of diversified products, economic problems in Japan caused by the war consequences, lack of financial resources, lack of raw materials, high inflation, and poverty. Due to the fragile condition of the enterprise, 1600 people left the company, while the workers who remained hired, were offered satisfying working conditions and salaries, as well as lifetime employment. During its thirteen years of operating, the company assembled only 2685 cars. Governing then president of the board - E. Toyoda, with the engineer - T. Ohno, were working on combining mass production with crafting methods. Because of the e.g., high employee competencies, workers' ingenuity, and openness for refreshed solutions, but also lack of resistance to the changes, conducting the experiments were possible. The great willingness for cooperation and flexibility of the managers led E. Toyoda to visit the Ford factory in the United States (more about the management system in Ford Company was discussed e.g., in: (Beynon, 1984), (Beynon & Nichols, 2006), (Buckman, 2009),(Levinson, 2002),(Monden, 2011),(Wilson, 1995)). Based on completed observations and experimentations, in the Toyota company, the Toyota Production System (TPS) was created. Its core consisted of (Haak, 2006),(Ohno, 1988), (Ohno & Bodek, 2019), (Pegels, 1984), (Wada, 2020), (Yang & Yang, 2013): complete waste elimination, striving to the reaching the most subordinate potential expenditures, guaranteeing the highest quality, and the process realization in the shortest possible amount of time. The evolution of Toyota Production System has been presented in the Table 1.