Improving Extrusion Process towards a Closed-Loop System by Using Lean-philosophy
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Suljetun materiaalikierron tavoittelu ekstruusioprosessissa Lean-filosofiaa hyödyntäen
The aim of the research was to find ways in the production of the case company as to how an extrusion process could be improved towards a closed-loop system. The primary goal was to find methods how the undesired output, plastic waste or scrap, could be eliminated. The Group’s target is to decrease the scrap percentage to 7.5 % (in the year 2015 it was 10.06 %). The secondary target was to study how scrap could be recycled inside the factory to valuable input, regrind. The current state of the core company was studied through participant and non-participant observation, through interviews and the analysis of the ERP- and BI-programs and also by working short periods in the production. Observation continued during the research and meant taking part in morning meetings and observing other daily operations. Numerical data showed the efficiency of the current extrusion process. Working in the production made it possible to see the production process from inside. The interviews and the analysis helped to discover the main development issues in the current state. Literature was used for surveying the requirements for the closed-loop system, for the concept of process-orientated thinking, elements of extrusion and for the study of plastics recycling. The literature about Lean-Philosophy was also important for this research. The most important results of the research concern development issues and recommendations of the raw material purchase, inventory and material management, the production process, recycling, information flows and daily management. Main problems were related to the lack of systematic and studied methods. Also the use of regrind requires scientifically studied and tested ratios, because its mechanical and processing properties (for instance MFI and bulk density) change during recycling. It was also noted that the performance of employees affects strongly the performance of the extrusion process due to its manual nature. The first recommendation is to correct issues relating to the sources of scrap because biggest financial benefits are related to it. Also the study on regrind ratios should start as soon as possible. This may require forming a project team due to the extent of the topic. The secondary proposal is to carry out issues that facilitate recycling and help to achieve a closed-loop system.