Quality assurance in low-volume assembly line at Scania

Detta är en Uppsats för yrkesexamina på avancerad nivå från Luleå tekniska universitet/Institutionen för teknikvetenskap och matematik; Luleå tekniska universitet/Institutionen för teknikvetenskap och matematik

Sammanfattning: Scania are now going through a transformation process from being a supplier of trucks, busses and engines to a supplier of complete and sustainable transport solutions. Scania's transmission assembly department in Södertälje is facing a variation of changing challenges linked to the powertrain and customer of tomorrow. Some of the challenges is related to assuring quality on low-volume electrified and hybridised products. In this thesis quality assurance of a low-volume assembly line at transmission's department has been investigated. The aims for the thesis project are to evaluate today's methods, equipment and process descriptions for how quality assurance are handled and how it can be implemented in a low-volume assembly line. The aim is to investigate what kind of quality assurance methods exist within Scania but also externally. The purpose is to give suggestions for Scania on which quality assurance methods are suitable for Scania's low-volume assembly line. Today the current level of quality assurance in a low-volume line is considerable low and the production have many processes between start and delivery. The production start with an order initiation which prints out a list of assembly order and included parts. The processes are manually handled by one operator from the beginning to the end and the work includes assembly, material picking and quality control. Due to limitations and lack of equipment, the assembler have a lot of responsibility. The processes are also lacking of traceability and have a high risk for allowing deviations to be build in the product. The current processes leads to increased risks of rework, longer lead time and lower quality. The thesis project started with a literature study with the focus on quality, quality assurance and lean production. A current state analysis was done to gain knowledge of the processes and to identify problems within the current state. Identified problems were through observations, interviews and analysis of PFMEA document. The problems were risks that could affect quality of the product, and it was then categorized into three major risk groups; pick, place and tools. To seek which equipment there are to handle these risks, how other companies and departments are working with quality assurance, internal and external study visits were carried out. Internally within Scania; Smart Factory Lab, Engine Assembly and Chassis Assembly. Externally; Volvo Group Trucks Operations Köping and Volvo CE Arvika. The results of the visits were evaluated to create a solution to make a suitable suggestion in term of cost, quality and flexibility for Scania. The thesis project resulted in a study that showcase what quality assurance methods and equipment existed on the market and what other companies are using to quality assure. The result is that for similar production, the companies are using rather similar methods and equipment. Equipment to handle risks, deviations involving picking materials and assembly. For Scania's low-volume production a solution and a recommendation of equipment was given. To handle the existing deviations and for upcoming similar low-volume production. Quality assurance equipment and methods are expensive but is considered necessary, a necessary cost and necessary waste. Scania is recommended to invest in short and long term solutions where the short term is to improve the current state. In a short term to secure the picking operations with easier solutions of dividing parts into boxes or trays on the cart during transportation from shelves. Installing pick to light connected to nutrunners for critical parts and further develop the digitalized checklist for improving visualization. In longer term, Scania should invest in quality assurance equipment for low-volume lines. Prioritize and invest in creating infrastructure for connection between equipment and tools to secure critical parts in early stages of the project. Finally, create a communication between Scania's internal plants in order to further improve and share the quality assurance knowledge.

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