In-plant materials supply: Supporting the choice between kitting and continuous supply

Doctoral thesis, 2012

This thesis focuses on the two materials feeding principles of “kitting” and “continuous supply” within in-plant materials supply in mass customised assembly. With the principle of kitting, parts are delivered and presented to the assembly operations in pre-sorted kits, with each kit containing parts for one assembly object. With the principle of continuous supply, a number of parts of each part number are presented at the assembly station where they are to assembled, which means that when continuous supply is used in a mixed-model assembly context, where different assembly objects require different parts, the assembler at each assembly station needs to pick the right parts to assemble on each assembly object. Depending on whether kitting or continuous supply is used, the performance of both in-plant materials supply and assembly can be affected. However, within industry, there is considerable confusion regarding which materials feeding principle should be used when. Moreover, the existing research literature on the topic is far from exhaustive. This thesis aims to provide knowledge of how the configuration and the context of the in-plant materials supply system should be considered when a choice between kitting and continuous supply is made. The research has been conducted mainly in the form of case studies at assembly plants within the Swedish automotive industry. Complementing the case studies, one experiment has been conducted. In several of the studies, it has been possible to study both kitting and continuous supply in the same setting, which has resulted in an excellent basis for comparison between the two materials feeding principles. The other studies have instead focused on aspects within each of the two materials feeding principles, enabling an understanding of how each of the two materials feeding principles can be applied and of how this can affect performance. The thesis provides a structured and thorough account of kitting and continuous supply and the effects of using these principles, depending on the configuration and the context of the in-plant materials supply system. This has previously been lacking. The structured and thorough account presented in the thesis contributes to an understanding of the benefits and drawbacks of kitting and continuous supply and the applicability of each of the materials feeding principles. The thesis further relates the choice between kitting and continuous supply to the design of an in-plant materials supply system as a whole and suggests an outline of such a design process.