Automotive Body Structure Assembly: Mass & Cost Saving Potential of Laser Welding Compared to Spot Welding
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Due to the continuously increasing demands on the efficiency of road passenger vehicles the National Highway Safety Traffic Administration (NHTSA) commissioned a project to determine the achievable mass savings on an average, mass produced passenger car which are obtainable with today’s or within close reach technology. The major part of this project is conducted at EDAG, Inc. One of the approaches made within this program is to reduce the weight of a vehicle’s body struc- ture by replacing the commonly on a mass production vehicle applied joining technology resistance spot welding with laser beam welding. The main advantage is the possibility to bisect the size of the flanges since laser welding requires less flange width compared to spot welding. A sample structure is remodeled twice to create one almost solely spot welded and one almost solely laser welded body structure of the same vehicle. Those body structures are represented by two FEM models. Proper representation of the joining technology is applied to both FEM models in preparation of NVH com- putation runs, ensuring the comparability of the two body structures regarding their performance. In cooperation with experienced production engineers two assembly layouts for the spot welded and the laser welded structures are developed. For those assembly layouts cost calculations are done to oppose the attained mass savings to the increase in production costs. The weight difference between the two versions is determined to a remarkable 12.2 kg for the ana- lyzed sample structure. The laser welded structure thereby displays a slightly improved NVH perfor- mance compared to the spot welded structure. Taking the exemplary cost increase for the assembly of certain parts of the lower body structure into account gave a weight saving efficiency of 4.58 $ per saved kg. For the field of automotive engineering this is a rather high value, mainly caused by the still very extensive costs for laser welding equipment. With laser welding technology being more and more adopted in mass production applications and most probably due technical improvements those costs are likely to decrease within the next few years. Even more mass savings could be achieved by adapting the design of the body structure more to the usage of laser beam welding.
Place, publisher, year, edition, pages
2012. , 115 p.
TRITA-AVE, ISSN 1651-7660 ; 2012:04
IdentifiersURN: urn:nbn:se:kth:diva-118794OAI: oai:DiVA.org:kth-118794DiVA: diva2:608422
Master of Science - Vehicle Engineering