Optimized assembly of light weight screw joints - OptiFastening
Purpose and goal
The project is focused on assembly of optimized screw joints for light weight constructions: Precision assembly of high strength steel screws and aluminium screws for saving weight in light weight designs of different materials and hybrid power trains. Develop a modeling technique for construction, preparation and production of screw joints to shorten development time by 20 % and fully utilize the performance. Develop a regression model for the prediction of relaxation and other performance of typical screw joints in different applications and environments. Process control and quality assurance methods based on ultra sound for tightening in the elastic and plastic regions of the screws will be evaluated and developed. To develop the web based Handbook (www.sfnskruv.se/handbok) in screw joint technology into the standard tool for information and guidelines in the automotive industry.
Results and expected effects
Within the participating companies the results will lead to better screw joint designs with lower weight and more secure operability. New production techniques will be adapted for assembly of high performing screw joints. In conclusion the outcome of the project will strengthen the competiveness of the Swedish automotive industry and contribute to reduced emissions of CO2, due to reduced weight in the power trains, chassis and bodies of cars and trucks. Developed precision assembly can give a weight reduction of 30 % of the screw joints. Yield point tightening can double the clamping force, meaning that the number of screw joints can be reduced significantly. Precision assembly also means quality assurance by process control, which reduces the need for tests after assembly. Optimized screw joints will be an enabler for increased use of lightweight materials. Lightweight design has the potential for 40 % weight decrease of components and systems. Better guidelines and modelling methods for screw tightening as well as calculation sheets for relaxation in work materials will be developed. The handbook in screw joint technology will be the common tool for design, advanced engineering and production of optimized screw joints in the Swedish automotive industry and its suppliers as well as in other production industry.
Approach and implementation
The four different WPs will be running parallel. A chairman from the industry and a project leader from the FoU is appointed for each WP. The details of the practical experiments will be decided by the project group. The experiments will be set up and performed at the participating companies. The results will be used for calibrating the models and refining the handbook. Reports, guidelines and new information for the web based handbook will be produced in the project to attain a wide circulation of new knowledge. Seminars will be arranged to disseminate the knowledge. The material can be used in technical education. Svenskt Monteringsforum and other media will be used for distribution of information.