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A study project spanning over six months, which has also become the subject of a thesis at the Polytechnic University of Milan, aiming to develop cutting-edge solutions for the electric mobility sector.

Brugola OEB has recently completed a significant study that lasted over six months, focused on the development of innovative solutions for electric vehicles (EV) This project has also inspired a university thesis, resulting from collaboration with a student from the Polytechnic University of Milan.

Project Objectives

The initiative arose from a customer’s need to develop a battery pack fastening system to the car chassis, aiming to minimize contact resistance and prevent energy losses. The main challenge was to find an optimal balance between electrical conductivity and corrosion resistivity of the screws used.

Technical Details of the Study

The study initially evaluated the mechanical and electrical properties of a specific bolted joint intended for battery pack applications. Four different coatings were tested to determine the most suitable one, with a particular focus on zinc/nickel coatings in both silver and black variants, with and without sealant. The sealant is essential to ensure high corrosion resistance and stabilize the coefficient of friction.

Another crucial aspect of the project was the tightening strategy, essential for the successful transmission of electricity. Using a four-terminal measurement system, known as a Kelvin double bridge, the voltage drop was measured to assess electrical resistivity, set within a maximum limit of 1.5 milliohms (mΩ).

Test Results

The initial tests showed that the black coating exceeded the electrical resistivity limit values. The optimal configuration turned out to be the one with silver zinc/nickel coating and sealant, which demonstrated improved corrosion resistivity. This choice was further validated through salt spray chamber tests, which simulate corrosive atmospheric conditions.

Impact and Future Developments

This study represents a significant advancement for Brugola OEB in developing innovative solutions for the electrical sector, addressing the growing needs of customers and the market. The project is highly topical and also of interest to the Association of German Engineers (Verein Deutscher Ingenieure), which is working on drafting the VDI2231 standard related to bolted joints for electrical transmission.

Brugola OEB continues to dedicate itself to research and development to offer high-quality, cutting-edge products, solidifying its position as a leader in the industry.