PROBLEMS SOLVING IN THE QUALITY FIELD USING THE SIX SIGMA APPROACH IN COMPANY GORENJE D.D.

Diplomsko delo zajema reševanje problemov na področju kakovosti s pristopom šest sigma v podjetju Gorenje, d. d. in izvedbo praktičnega primera delavnice po metodologiji DMAIC. Namen delovnega procesa je, da z njim zagotovimo izdelke ustrezne kakovosti kupcem in s tem zadovoljimo njihove potrebe. Šest sigma je torej zelo uporabna metoda za izboljševanje in odpravo različnih napak, ki se pojavijo v procesih. Diplomsko delo predstavlja »green belt« nalogo iskanja možnih izboljšav, zaradi nabiranja ledu na kanalih hladilnika HKS 3666. Nabiranje ledu v odtočnem kanalu je povzročila premajhna moč grelca. Testiranja različnih grelcev so omogočila izbiro najbolj optimalne rešitve glede uporabnosti in cene. Namesto grelca z močjo 1,5 W se je uporabil grelec 3 W. Pri testiranju rešitve smo uporabili tako imenovani »gorila test«, katerega je izbrana rešitev prestala. Težavo pri delovanju programa nastavljene temperature odtaljevanja hladilnika smo odpravili s popravilom in optimiziranjem programa. Program smo testirali v razvojnih laboratorijih. Prav tako smo pripravili servisni program za hladilnike, ki so že na trgu. Težavo nabiranja ledu na stiroporni vložek EPS, je povzročila premajhna distanca med uparjalnikom in stiropornim vložkom ter hrapava površina stiropornega vložka EPS. Ta problem smo rešili s kontrolo debeline stiropornega vložka, merjenjem distance in dodatnim fiksiranjem stiropornega vložka s posebnimi plastičnimi distančniki. Hrapavo površino smo odpravili z izdelavo novega stiropornega vložka, ki ima bolj gladko površino.The diploma thesis describes problems solving in the quality field using the Six Sigma approach in the company Gorenje d.d. and the realization of a practical example of work shop in accordance with DMAIC methodology. The purpose of work process is to assure products of suitable quality to the clients and in this way satisfy their needs. The Six sigma method is a very useful method for improvement of processes and elimination of different failures which appear in them. The diploma thesis illustrates »green belt« task of searching possible improvements in the case of ice formation in channels of refrigerator HKS 3666.Ice formation in sink channel was a consequence of too low heater power. Testing of different heaters enabled to choose the most optimal solution as regards the use and price. Instead of the heater with power 1,5 W, the heater with power 3 W was used. While testing i.e. searching the solution, we used the so called »gorilla test« - a test which the chosen solution has passed. The problem with operation of the programme of set temperature for refrigerator defrosting was eliminated by repair and optimization of the programme. The programme was tested in development laboratories. Besides, service software for refrigerators which are already on the market has been made. Ice formation on styrofoam insert EPS was caused by too short distance between the evaporator and styrofoam insert and by rough surface of EPS insert. This problem was solved with control of thickness of the insert, with measuring of the distance and with additional fixing of the insert by means of plastic spacers. Rough surface was eliminated by manufacture of new styrofoam insert with smoother surface