Feasibility study for geometry assurance in low volume manufacturing of complex products : With application in the shipbuilding industry

University essay from Blekinge Tekniska Högskola/Institutionen för maskinteknik; Blekinge Tekniska Högskola/Institutionen för maskinteknik

Abstract: Geometrical variation is an unavoidable aspect in all types of manufacturing that may, unless managed, risk failure in fulfilling product requirements which may result in rework, delays and bad publicity. The term geometry assurance includes the tools, methods and processes that can be utilized to manage the effects of geometrical variation and to ensure fulfillment of esthetical, functional and assembly requirements. While state of the art research in geometry assurance is extensively applied within the automotive and aerospace industries with great success, its application in low volume manufacturing of complex products remains limited. The shipbuilding industry is an example of such an industry, often manufacturing large and complex products in low quantities. Further, the shipbuilding industry has historically been labor-intensive and relied on craftsmanship throughout the product realization process. However, studies indicate that a technology-intensive development is crucial for companies in order to maintain market competitiveness. This transition places high demands on a well-established geometry assurance process in order to ensure successful assembly and fulfillment of product requirements.  In this thesis, a feasibility study is conducted on how geometry assurance may be applied in low volume manufacturing of complex products. By developing guidelines on how geometry assurance may be applied, the purpose is to improve geometrical quality throughout the product realization process and to reduce lead times, costs and increase assembly precision.  To explore the feasibility of geometry assurance in low volume manufacturing of complex products, a work structure consisting of three phases was established. In the first phase, a current state analysis of the collaboration partner Saab Kockums was conducted parallel to studying state of the art research in geometry assurance. In phase two, the state of practice of companies in the automotive and aerospace industries was studied in order to determine how they apply state of the art research. By interviewing industry specialists and combining gained knowledge from the first two phases, guidelines on how geometry assurance may be applied in low volume manufacturing of complex products was developed. In phase three, based on these guidelines, suggestions on how the geometry assurance process in pipe manufacturing at Saab Kockums can be improved was developed. The results of this study indicate that geometry assurance is applicable in low volume manufacturing of complex products. However, alternative methods may be required. Based on gained knowledge and insights from interviews with industry specialists, guidelines on how geometry assurance in low volume manufacturing of complex products may be applied are proposed. In order to improve the geometry assurance process in pipe manufacturing at Saab Kockums, this study proposes general guidelines for improvement along with a process and prototype measurement tool for the fitting-pipe methodology. The specially designed prototype measurement tool presents an alternative measurement method that can be used in cramped spaces where it is difficult to access with a 3D-measurement arm, the proposed primary measurement technique. In conclusion, this study indicates that geometry assurance is applicable in low volume manufacturing of complex products and suggests three methods for how it may be achieved. However, each of these methods needs to be further investigated in order to determine their applicability in other low volume manufacturing industries. Further, the prototype measurement tool and process for the fitting-pipe methodology indicates potential for improving the geometry assurance process in pipe manufacturing. However, further work is needed to complete the process for fitting-pipes and to finalize the prototype measurement tool for production use.

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