Automated paint shop in heat pump mega-factory
The new powder coating paint shop covers an area of 10,000 m2, spread over two halls. Pre-treatment, painting and cross-linking take place in the first, 6000 m2 hall. In a section of the second 4000 m2 hall, the finished products are distributed to eleven hanging stations. Workpieces made of galvanised sheet metal or black steel measuring up to 1900 x 2600 x 400 mm (H x L x W) can be coated, in reality a product carrier fitted with various components passes through the process steps. The maximum weight that a single conveyor carriage can transport is 120 kg. For the painting process, two equivalent painting stations are available at the paint-shop, each with a six-stage chemical pre-treatment, a drying oven, a Gema painting system and a curing oven.
Wasterwater recovery in Pre-treatment
During pre-treatment, the workpieces are first subjected to alkaline degreasing, followed by three rinses, the last of which is carried out with demineralised water. A zirconium-based conversion coating is then applied to the components and finally rinsed one last time with demineralised water. The wastewater is purified using a fully automatic wastewater recovery process with a vacuum distillation system. This means that the purified water can be recirculated, and the overall water consumption of the system is very low. All sinks in the pre-treatment process are recirculated and continuously cleaned.
Each installed tank also contains mechanical filters to catch large particles or detached masking components. A belt filter is installed in the tank for alkaline degreasing, which separates oil films from the surface. A rinsing cascade system is also implemented, in which fresh demineralised water is added in the last rinse. Excess water flows back into the previous rinses to maintain the rinsing media quality. Sensors monitor pH and conductivity to ensure optimum process control and chemical quality. The chemical additives are topped up based on these measurements.
Chemical pre-treatment before powder coating
After chemical pre-treatment, the workpieces are dried in one of the two installed drying ovens at temperatures up to a maximum of 140 °C. The temperature can be adjusted to the existing residual moisture. A blow-off system is also installed at the end of the pre-treatment process to ensure final dryness before coating. The workpieces can be fed from the two pre-treatment lines into either a white paint booth or a quick colour change booth.
In the white coating booth, the powder is only applied in this colour. Due to the high throughput, the white powder coating can be refilled into the powder centre directly from big bags. Other colours are applied in the second newly installed paint booth, which is specially designed for quick colour changes. During the process, the powder coating is recycled via a paint cleaning and regeneration system. In both booths, 20 automatic spray guns apply the powder. A manual painting station is also available for post-processing the parts.
Fast curing of powder coating
Alternatively, the workpieces can be fed to a buffer and then returned to the painting booth. The target thickness of the powder coating applied is between 30 and 130 μm, with a tolerance of ± 10 μm on the visible surfaces. The subsequent cross-linking of the paint takes around 10 minutes at a material temperature of 200 °C and is carried out in natural gas-heated convection ovens.
The workpieces are transported between the individual process stages in the paint shop using a P&F conveyor that covers a distance of 3385 meters and is equipped with 25 drives. The products are distributed to four different product carrier types at three hanging stations with two levels. Special hangers are used for each product and each type of suspension, which remain on the trolleys while only the end components, the hooks with goods, are replaced. In this way, proper earthing can be guaranteed at all times during the coating process.
Painted parts directly to final assembly
It is crucial for the efficiency of the entire paint shop that each product is hung correctly and arrives at the correct hanging station. This is particularly true as the conveyor system is designed for material logistics in the assembly process, where the painted parts are delivered directly from the conveyor to specific assembly stations.
The experts at ITS have therefore adapted their own control system ‘HiVision’ to the process on site in close cooperation with Vaillant. It is now directly linked to the ordering system, allowing the entire production flow to be optimised, including the placement of parts on the individual trolleys. Each hanging station is equipped with a large screen that displays the exact hanging method and the required hanging fixtures.
Maximum paint shop efficency
The control system manages which trolley goes to which workstation and what is to be hung on it, and stores the details of the processed order in the database. This guarantees the highest possible utilisation of the paint shop capacity and reduces the possibility of errors. Each segment of the system has also been designed with a focus on redundancy and efficiency, which is reflected in the dual design of the key components. The plant complies with the strictest European standards and local regulations.
„This is one of our largest projects to date. The team, including the investor, implementer, and design office, was driven by a clear objective and vision to complete everything within the set timeline and quality standards. We are immensely proud of our team who spent over a year preparing the site and nearly another year on installation. This paint shop is a symbol of Industry 4.0 technology and unmatched precision in human craftsmanship across Central Europe.“
More information: www.itsbrno.cz