San Luis Potosí, Mexico. – BMW, the German manufacturer of luxury and high-end automobiles, received the editorial team of La Revista del Color México at its facilities in San Luis Potosí, with whom BMW shared the latest innovations in sustainability and industry 4.0 currently implemented in their painting process. These facilities are the newest in the BMW Group Global Production Network.
Exclusively for La Revista del Color Mx, BMW México opened the paint and surface finish area’s doors, where we had the opportunity to talk with Lourdes del Ángel, Paint Finish Manager, and Lev Aguirre, Manager of processes, materials, pretreatment, anticorrosion coating, and water treatment, who leads the areas of final quality assurance and pretreatment, water and energy respectively.
Before entering the painting area, you can see from the outside the way in which the car bodies are delivered by a conveyor belt carrying them under controlled temperature and humidity, to prevent the steel and aluminum from being attacked by moisture or contaminated with particles.
After a safety talk, we dressed ourselves in the safety outfit to access to see the painting line, which consists of four levels, where automated processes are combined with focus on the detail and flexibility of the plant personnel.
Lev and Lourdes alternated their participation during the tour of the painting area, where they explained the latest innovations in painting, coatings, insulation, industry 4.0, and sustainability.
Painting process
Regarding the vehicle painting process stages at the process, Lourdes pointed out that there are eleven stages, starting with the arrival of the bodywork, where a cleaning process is carried out in tanks and in which the objective is to remove all the dust, metallic impurities and grease/oils the part may bring from previous processes. The next step is an anti-corrosion and e-coating treatment, which serves to protect the unit against rust.
Lourdes explained: «we have a twelve-year guarantee with our final customers, so anti-corrosion treatments are of the utmost importance for BMW».
She continued, “then we have the sealing area, where we reach all the joints between the metal parts ensuring water does not enter, and we also cover the entire lower part of the unit to avoid sounds or damage from splashes or objects on the way. We also have the engine areas coating, as it is where we can have contact with the water. Then follows the process of inspection of the surface of the e-coated surface, as for BMW it is very important to ensure the quality from the first base of the painting”.
Through the tour, the active presence of female collaborators stands out in all the processes of the painting department, such as Lourdes herself, who leads a diverse team of almost one hundred technicians. BMW has emphasized that diversity in its work teams promotes innovation and best practices in its plants around the world.
Continuing with the subject of painting processes, Lourdes mentioned “another very relevant process is the application of foam in the hollow spaces, which helps prevent noise and vibrations, following with the application of wax in the cavities of the car. This helps us to protect the interior surfaces from moisture that can condense inside the unit and thus prevent corrosion.”
After the sealing phase, Lourdes explained the paint application process, with the use of an intermediate oven to dry the base 1 and 2, followed by the application of the clear one and then an oven to cure the final finish characteristic of BMW.
About the industry 4.0 implementation in the processes within the painting and insulation area, Lourdes told us about the three main devices: in the measurement at the end of the line (EOL or «End Of Line Measurement») that verifies the color and finishing on the outer surface of the body; or Automated Optical Inspection (AOI or “Automated Optical Inspection”) that identifies surface imperfections by taking pictures every five millimeters, thereby simplifying statistics and troubleshooting; and the last one, which is connected to the AOI, is the marking cell, which marks the location of the imperfections found, helping the inspectors to correct any detail.
Lourdes pointed out that technology at BMW is a key element in the manufacture of its vehicles, but the human factor continues to be essential to obtain the high standards for which the company is known around the world. “Robots simplify the work of our collaborators, and they refine the details that the machines have done. It is a teamwork».
A highly sustainable operation
When asked about sustainability, Lev explained the BMW production site in San Luis Potosí has two water treatment plants, one of them only for the painting area. He explained the water used in the pretreatment and anticorrosion coating application processes is recovered and returned to the painting area.
Lev added “one of the particularities of our factory is the wastewater plant has a biological process, with a bioreactor in which bacteria remove organic components. The result is an additional 60 percent recovery. This is the focus that our people must improve processes and reduce water consumption”.
Regarding energy consumption, Lev noted that one of the innovations begins in the pretreatment with a system of rotating supports, which rotate the bodywork inside the tanks, ensuring that the entire surface is covered. This process reduces the amount of water required, with smaller tanks and lower energy consumption.
He noted “in the paint application area, an Integrated Paint Process (IPP) is used, which does not require a primer coat, or “primer”, nor an oven to cure it. Additionally, we have a system for recovering excess dry paint. This system also does not use water, increasing the efficiency of all processes and further lowering the levels of water and energy consumption”.
From the beginning in the design of the plant, a concept of residual heat recovery from the furnaces was generated, which is used for chemical pre-treatment and heating processes, thereby avoiding the use of additional boilers.
At the end of our tour, the BMW San Luis Potosí team showed us an automated bodywork warehouse, where more than 400 bodies can be stored, including unpainted and painted bodies. This space allows responding to last-minute color changes by customers or responding to changes in the production sequence.
An additional challenge for this painting line lies in the degree of customization that customers can make of their units, so the communication of the painting area with the rest of the plant is very important, allowing a timely response to the needs that are presented to them.
Lourdes pointed out “it is precisely the support in new technologies and robots that allows us greater flexibility and helps us to direct the efforts of our technicians to the personalization of our high-end vehicles”.
The editorial team of La Revista del Color México thanks Julián Argüelles for the facilities provided to carry out this visit for the preparation of this report.
