Key characteristic coupling and resolving key characteristic conflict

Abstract

Real complex assemblies have to deliver large number of customer requirements. Assemblies in general have many parts which work together to deliver those requirements. The involvement of many parts and presence of many requirements to be delivered, results in the involvement of a part in the delivery chains of more than one requirement. As a result most of the requirements are not delivered independently. Coupling among the requirements makes it hard to achieve all the requirements with in their respective tolerance limits. The thesis gives classification of nature of relationships that can exist among various requirements. It discusses characteristic of each relationship and how it can affect the robustness of an assembly. When the requirements in the assembly are conflicting, i.e. reduction in variation in one of the requirements increases variation in conflicting requirement, it tends to become non-robust. Non-robust assemblies entail high manufacturing costs. Aim of the thesis is to identify the scenarios of conflict in the assembly. Screw theory can be used to find the presence of coupling among requirements in the assembly. It can also be used to identify the nature of coupling. If coupling suggests that requirements are coupled, we analyze the intensity of the conflict. Not all conflicts need to be solved. Only the conflicts that will make assembly miss tolerance limits on its requirements need to be solved. The thesis outlines some of the methods that can be used to either resolve conflict or reduce the amount of conflict in the assembly. Conflicts can be removed from the assembly by making suitable changes in design. Design changes will modify DFCs of the conflicting requirements. Use of appropriate assembly techniques can also remove conflicts from the assembly. An assembly without any conflicts is more robust and can be produced at a less cost as compared to the one having conflicts.