W artykule przedstawiono wyniki badań dotyczące doskonalenia procesu wytwarzania stalowych rur zgrzewanych z powłoką Al-Si przeznaczonych na elementy układów wydechowych z wykorzystaniem metodologii Six Sigma. Doskonaleniu poddano jednostkowy proces badania rur zgrzewanych metodą roztłaczania. Procedura postępowania była zgodna z algorytmem DMAIC. Wyniki badań przedstawiono za pomocą wybranych narzędzi statystycznych.
The main target stated by the creators of this methodology is a radical improvement in the quality of goods (services), in the way of minimizing the changeability of the process, with application of statistic tools. The Procedure of performance, connected with improvement of quality of the stated process, product or service, is detaily defined by the further steps of execution of the so called six sigma project, i.e. DMAIC (Define - Measure - Analyze - Improve - Control). In the Six Sigma approach, the quality is referred to as "right to value". That means that the customer requires some value from the product delivered to him, i.e. some expected application and aesthetic features, reliability, etc, for which he is ready to pay. On the other hand, the organization possesses a well-justified right to expect big value from the product - the product must not produce costs, it has to "make" money. Hence, the very sense of Six Sigma is the appearing of "win-win" situation where the needs of the organization and the customer meet. The project was executed at a facility of a company producing welded steel tubes with Al-Si coating, both smooth and perforated, provided for elements of exhaust systems. During manufacturing of tubes in one of the lines, two kinds of waste pipes are produced. The first reason for production of scrap is stopping or restarting the operation of welding line after resetting, resulting in a non-welded or poorly welded section of tube. The second reason for production of scrap pipes are technological tests conducted by line operators, based on expanding and pressing through a section the tube to check the quality of weld. An expanded tube goes for scrap. According to the control cycle, two samples are checked per each batch of tubes. The aim of the project was to reduce the quantity of scrap from technological tests by ca. 70 %, without intervention into the quantity of sampled sections of tube in the technological line.