häwa GmbH, which specializes in the manufacture of custom control cabinets and machine frames, has created a state-of-the-art facility with its new powder coating plant. The new building was designed with maximum energy efficiency, automation, and flexibility in mind and sets new standards for the company.
There were several reasons for the new facility. Over the past 25 years—the age of the previous facility—the range of parts has changed. Today’s parts are in some cases larger and heavier, and more complex geometries are also more common at häwa. In addition, batch sizes have decreased while the variety of parts has grown, requiring greater flexibility. Last but not least, häwa wanted to take a step forward in automation to address issues such as the shortage of skilled workers. The Swabian company has also placed a major emphasis on energy consumption. häwa is meeting this challenge with an efficient energy concept.
As a first step, the company relies on a six-zone pretreatment process, with the supplier Alufinish using a modern zirconium nanopassivation system. The technology used has no phosphate, which minimizes wastewater issues while still meeting high corrosion protection standards. Components achieve a durability of over 1,000 hours in the salt spray test. The use includes degreasing and multiple rinses with cascaded deionized water, which reduces both water consumption and carryover.
A particular highlight of the pretreatment at häwa is a rotary blower at the end of the process: this efficiently blows off residual water, minimizing the drying requirement in the residual water dryer. Thanks to a partnership with a neighboring sawmill, häwa also utilizes its partner’s wood waste incineration to generate renewable energy for the pretreatment process. In addition to environmental benefits, the company thereby reduces its reliance on fossil fuels and creates regional economic value.
Flexibility and Automation
The actual powder application is performed using two identical powder booths from Gema, which are specifically designed for small batch sizes and a wide variety of variants. One of the booths is already equipped with a robot from CMA Roboter GmbH, which handles the front and corner coating. The robot is programmed using a teach-in system, in which the movements are manually specified and stored by an experienced operator. This method allows for flexible adaptation to the sometimes complex geometries of the workpieces.
Currently, only one of the powder booths is equipped with the robot; however, the identical design of the booths provides an optimal foundation for a second robot. The powder coating booths themselves are designed with individually controllable feed axes for precise coating of large interior surfaces of the products.
häwa processes all standard powder coatings available on the market and must meet the requirements of various customer standards. Thus, flexibility in paint supply is a must: “Up to five color changes a day are normal for us,” explains Arno Müller, Managing director of häwa GmbH. The painting system supports this with a sophisticated color-changing system that operates independently for each booth. The automatic control ensures homogeneous color distribution.
Not only are different color shades processed, but special coatings such as ESD coatings are also used. The company also uses multi-layer powder coatings when, for example, high environmental stresses are expected for the control cabinet. Additionally, a manual booth is available for the manual powder coating of special orders and touch-ups.
Temperature Zones for Maximum Efficiency
When it comes to oven technology, häwa traditionally relies on natural gas. At 95 °C, the temperatures from the wood-fired heating network are too low for the curing oven, and gas is currently still the most economical solution, explains Müller. To minimize natural gas consumption, the curing oven and water-removal dryer are divided into different temperature zones—also to minimize energy losses.
In addition, the oven doors are designed so that they can be opened in three different sizes, ensuring that as little heat as possible escapes depending on the item being painted. At the same time, the oven infrastructure is designed so that it can be converted to hydrogen in the long term—an important element for the plant’s future-proofing. Starting in 2030, the local energy provider plans a pilot project using hydrogen in the region, which is likely to have an impact at häwa as well.
Heat recovery also contributes to high efficiency. After passing through the curing oven, the coated parts release their excess heat into a specially enclosed area that runs parallel to the water-carrying air dryer for approximately 40 meters. The energy is used to heat this area, which significantly reduces the required heating capacity.
Parts that previously came out of the baking oven at 160 °C now leave the oven area at around 110 °C and can thus be processed further more quickly. “All in all, we have nearly halved our primary energy consumption,” explains Managing Director Müller.
The system was designed in close collaboration with specialists from Rippert GmbH. häwa is clearly satisfied and, with the new coating system, is now much better equipped to meet the challenges regarding energy, cost efficiency, automation, and flexibility. The company is thus well-positioned to compete and able to provide customers with customized solutions.
