Izboljšava kakovosti procesa visokotlačnega litja aluminijastih izdelkov

Šušteršič, Gašper (author), Bračun, Drago (mentor)

Pri visokotlačnem litju se v serijski proizvodnji pojavljajo različne napake na ulitkih. Za njihovo zaznavanje je potrebna sistematična kontrola ulitkov, ki med drugim vključuje tudi časovno in izvedbeno zahtevno rentgensko kontrolo. Cilj serijske proizvodnje je obvladovati proizvodni proces in procesne parametre do te mere, da defektnih kosov ne bo, pri čemer tudi 100 % rentgenska kontrola ne bo več potrebna. V diplomskem delu je prikazana vpeljava ulitka v serijsko proizvodnjo. Največje odstopanje pri kakovosti je predstavljala poroznost v ulitku, ki jo zaznamo z rentgensko kontrolo. S pomočjo 6sigma metode smo skozi preizkuse litij izboljšali tlačno orodje in posledično izboljšali kakovost ulitka. S Taguchi metodo smo raziskali vpliv tlaka III. faze na poroznost v ulitku. Na podlagi raziskav smo definirali ustrezne procesne parametre, s katerimi smo izmet na 100 % rentgenski kontroli zmanjšali na manj kot 5 %. Ugotovili smo, da delovanje vakuuma in obrabljen livni bat najbolj vplivata na nastanek poroznosti v ulitku. Na podlagi teh ugotovitev smo prešli iz 100 % rentgenske kontrole ulitkov na vzorčno kontrolo. S prehodom na vzorčno kontrolo smo proizvodne stroške enega ulitka znižali za 9 %. S spremembo mazanja tlačnega orodja smo izboljšali produktivnost procesa, saj smo čas enega cikla zmanjšali za 23 %. Po predstavljenih izboljšavah je proces obvladovan, pri čemer je skupen izmet po vseh delovnih operacijah nižji od 7 %.

• Language: Slovenian
• Keywords: visokotlačno litje, napake litja, preizkusi litja, izboljšava procesa, 6sigma, Taguchi metoda
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [G. Šušteršič]
• Year: 2023
• Number of pages: XXII, 73 str.
• PID: 20.500.12556/RUL-148959
• UDC: 621.74.04:669.71:658.5(043.2)
• COBISS.SI-ID: 165441795
• Publication date in RUL: 02.09.2023

ŠUŠTERŠIČ, Gašper, 2023, Izboljšava kakovosti procesa visokotlačnega litja aluminijastih izdelkov [online]. Bachelor’s thesis. Ljubljana : G. Šušteršič. [Accessed 23 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=148959

Secondary language

• Language: English
• Title: Quality improvement of the high-pressure die casting process of aluminum products

Abstract

In high-pressure die casting, various casting defects occur in serial production. To identify these defects, a comprehensive inspection process is necessary, including X-ray inspection, which is both time-consuming and demanding in terms of execution. The objective of this production process is to attain such control over the manufacturing process and its parameters that defective pieces are eliminated and X-ray inspection of entire serial production will no longer be necessary. The most significant quality issue encountered was the presence of porosity in the casting, which can be identified through X-ray inspection. By implementing the 6sigma method, we improved the tool pressures and consequently the quality of the casting. Additionally, utilizing the Taguchi method, we investigated the impact of the 3rd phase pressure on porosity formation in the casting. Through our research, we defined the appropriate process parameters that helped reduce the rejection rate to less than 5 % in 100 % X-ray inspection. Our findings revealed that the vacuum conditions and the condition of the casting piston have the greatest influence on porosity formation in the casting. Based on this knowledge, we transitioned from 100 % X-ray inspection to sample control. By adopting sample control, we decreased the production costs of each casting by 9 %. Furthermore, we enhanced process productivity by altering the lubrication of the pressure tool and reducing the cycle time by 23 %. After implementing all these process improvements, the manufacturing process is now effectively controlled, resulting in a total scrap rate, encompassing all work operations, of less than 7 %.

• Keywords: high-pressure die casting, casting defects, casting tests, process improvement, 6sigma, Taguchi method