Application of part kitting methodology in high variation automotive assembly processes : case study at Ford Motor Company Valencia, Spain

Abstract

Customers put more and more pressure on the market to get quality products timely delivered for low prices and request a wide variety of models and variants. Automotive manufacturers are mass customizing in order to meet their customer’s needs, which leads to higher variation and increased amount of parts. These parts are delivered to the assembly line by mainly four different material feeding principles: continuous supply, sequential supply, batch supply and kitting. These principles are captured in the theoretical framework for this study. In this master’s thesis, a model to compare the different material feeding systems in high variation serial production assembly lines is established. The model consists out of a mathematical model and an analytical hierarchy process, which weights selected criteria. It includes preparation, transportation, picking, storage and work-in-progress costs and compares lineside storage space, operator picking time, required picking space, lineside replenishment, kitting preparation time and lineside inventory value with each other. The target is to minimize lineside storage space, sequencing and logistic cost, operator displacements and to be more flexible in rebalancing work steps from one workstation to another. Savings and investments are quantified in a business case approach. The thesis focuses on the special requirements of the space restricted Ford Valencia plant but can be adapted to any other automotive assembly facility. Furthermore, the design of a kitting process for feeding material to the assembly line is defined. The results presented show that kitting has a higher cost impact as line side stocking. However, the case study demonstrates that kitting can be an alternative to lineside storage due to limited space. Whether kitting is preferable depends of the special requirements of a company. In the case of Ford Valencia, the analytical hierarchy process demonstrates the necessity to reduce lineside storage. Therefore, kitting can be seen as a very suitable material feeding system. However, other companies might value other criteria higher which leads to the choice of a different material feeding system. Using an analytical hierarchy process beside a business case calculation is therefore indispensable for OEMs thinking about the introduction of kitting. With the introduction of kitting, the increased complexity of producing more models and derivatives can be managed. Evidently, kitting reduces man-hour consumption of operators at the assembly line by presenting parts closer to the assembly object. Moreover, kitting can facilitate balancing work tasks of the assembly line. Rebalancing work task from one workstation to another results in potential savings that are difficult to quantify. The biggest interest for further investigations is to be able to quantify this qualitative effect. Beside these effects third party kitting and the combination of kitting and continuous supply are areas for further research. Such an interacting and reciprocal approach can combine the benefits of both kitting and continuous supply.