Perfect paint pretreatment of agricultural machinery parts

An adapted overhead conveyor continuous blast machine ensures perfect paint pretreatment of the blast structures weighing up to 2 tons at a Brazilian manufacturer of agricultural machinery.

Optimum paint pretreatment is a must to ensure that agricultural machinery still looks good under all climatic conditions, even after years of use. A significant contribution to this is made in the new plant of a large, globally active Brazilian manufacturer by the Rösler RHBD-K 22/27-HD overhead conveyor continuous blast cleaning system, which is customized to the customer's specific requirements. Integrated into the fully automated production line, it enables part-specific cleaning blasting of three-dimensional steel structures weighing up to 2 tons before painting.

The Brazilian company's innovative agricultural machinery is used, for example, for the harvesting of coffee beans and sugar cane as well as the application and care of crops in more than 100 countries. The success factors of the products are their outstanding performance and quality, which are also based on continuous improvement of production workflows and processes. Accordingly, a fully automated, digitized production line is being built at a new plant in Brazil, where sheets and profiles are cut to size, welded together to form steel structures, and continuously blasted and painted. For shot blast cleaning, the company chose the RHBD-K 22/27-HD overhead conveyor continuous blast cleaning system from Rösler due to the concept, technical implementation and quality, which were optimally adapted to the requirements. The parts are transported by the Power & Free transport system of the production line, for which a perfect coordination of the interfaces between the individual trades could also run optimally thanks to the Brazilian Rösler subsidiary.

After the welding process, the assemblies pass through a pre-chamber to the actual blast chamber, which is equipped with 12 Gamma 400G turbines and a drive power of 11 kW each. The high-performance turbines developed by Rösler have Y-design throwing blades. The special design with an optimal angle of curvature significantly increases the throwing speed compared to conventional turbines, enabling up to 20% higher blasting performance and significantly shortening process times.

In line with the enormous variety of parts, the system is designed for cleaning blast cleaning of welded assemblies with dimensions of up to 10,000 x 2,000 x 2,500 mm (L x W x H) and a maximum weight of 2,000 kg. In order to achieve the required blasting result of Sa 2.5 and the specified surface roughness values for optimum paint adhesion with large, thick-walled structures just as reliably and without distortion as with more sensitive, thin-walled components, the turbines are frequency-controlled. In combination with automatic abrasive flow controls, the machining process can be optimally adapted to the respective assembly. Part-specific program selection is made via the master computer of the overall system. Geometrically complex component areas such as undercuts can be partially blasted manually in the free blast house directly adjacent to the blast system's post chamber. The abrasive that falls down during this process is returned to the central abrasive treatment system via screw conveyors and cleaned, so that no additional treatment is required for the free blast house.

Rösler was also able to convince with the wear-resistant design of the system. This includes the fact that the blast chamber, which is made of manganese steel as standard, is additionally equipped with 10 mm thick, easy-to-replace plates made of the robust material. Another plus point is that the throwing blades can be used on both sides, which allows at least double the service life. They can be changed easily by means of a quick-change system with the turbine installed. (OM-06/23)