New preservation line placed into existing building containing an overhead crane

Founded in 1905 in the city of Hamburg as hardware store, the Carl Spaeter Hamburg company became one of the leading steel suppliers for retailers, mechanical contractors and industrial manufacturers in Northern Germany and beyond. The company’s success is based on a broad line of steel products with an inventory of more than 25,000 tons, short delivery times, high operational flexibility and numerous steel processing and refinement services. Mike Barz, general manager at Carl Spaeter Hamburg, explains: „Since our existing shot blast & painting line had reached the end of its usable life, and because we wanted to improve our customer support, we purchased the KON 34/6-HD from Rösler“. The equipment supplier from Untermerzbach in Southern Germany won this substantial purchase order against two competitors for the following reasons: Rösler adapted its equipment concept to the customer’s requirements. At the same time the customer was impressed by the quality and sturdy equipment design and Rösler could show several reference plants in the field. Reyk Hagelberg, plant manager at Carl Spaeter Hamburg, continues: „Within a very short time period Rösler, with input from us, developed a viable equipment concept that was perfectly adapted to our existing building and our technical requirements.”

Fully automatic, energy-saving shot blasting
A critical customer demand was that the line must be able to handle steel components, up to 3,200 mm wide, 400 mm high and a length of up to 21.2 meters. Moreover,  Rösler had to make sure that steel plates with a thickness of 4 mm could be shot blasted with the same high-quality cleaning results as plates with a thickness of 100 mm. An additional requirement was that all surface areas and edges of steel beams were perfectly blasted and received optimal paint coverage. Since the steel components have a max. weight of twelve tons, the design of the roller conveyors and cross transport systems had to be extra sturdy.
Special sensors measure the height of the steel components – in the case of steel plates also their width – that have been placed on the inlet roller conveyor of the preservation line. The PLC then automatically determines how many turbines must be turned on to clean the respective components. Other parameters like travel speed, paint type and paint thickness are also part of the processing programs, which are stored in the PLC and can be called up from the operating panel. In a first step the steel components are passing through a pre-heater that prevents moisture from being carried into the shot blast machine. The exhaust air from the pre-heater is guided to the paint drier, which helps to reduce the drying time of the applied paint.
From the pre-heater the work pieces are transferred to the shot blast machine. The machine housing is made from manganese steel. In addition, the blast chamber is lined with overlapping liners made from manganese steel. Eight high-performance Gamma 400G turbines, each with a drive power of 22 kW, ensure that the specified cleanliness of SA 2,5 is consistently and safely achieved at a travel speed of up to 4 meters/minute. Compared to conventional blast wheels, the Gamma turbines with curved throwing blades in “Y” design achieve an up to 20 % higher blast performance and, at the same time, reduce the energy consumption. Residual blast media and dust on the shot blasted components is removed with a combined brush-off/blow-off system at the exit of the blast chamber.

Low paint usage and minimal overspray
To meet individual customer requirements for the coating operation utilizing a water-based primer, the integrated automated spraying equipment is equipped with two independent paint application systems. Prior to the paint process special sensors precisely measure the work piece dimensions – down to the last mm. The gantry holding the spray guns is then programmed for these measurements. This ensures that the primer is only applied onto the surface of the respective steel components. The result is a minimum of overspray and the prevention of unnecessary waste of the valuable resource paint. The paint filter with air extraction points on both sides of the transport system collects any residual paint overspray. The filter is extremely effective! The residual dust load in the clean air is only 0.2 mg/m³ and, therefore, considerably below the official standard specifying a maximum of 1 to 2 mg/m³.
The residual dust in the clean air coming from the dust collector of  the shot blast machine amounts to 1 mg/m³, well below the legal limit of max. 3 mg/m³. Reyk Hagelberg explains: „With the new Rösler preservation line we can run our surface treatment operations for steel plates, beams, pipes/tubes and steel bars not only with an excellent finishing quality but also in a highly eco-friendly manner.” Heating the paint drier with exhaust air from the pre-heating system is a further contribution towards  resource-saving operations.

Optimized manufacturing processes and material flow
The work piece transport system of the new preservation line was integrated into a building with overhead crane already existing at Carl Spaeter. The roller conveyors with forward and reverse transport direction cover all four bays of the building with an area of over 42,000 square meters. This arrangement guarantees a highly flexible material handling operation. For example, it allows the transport of steel components from anywhere in the building to the preservation line, to other areas in the building or to the truck load station. The cross-transport systems, placed to the left and right of the roller conveyor, offer plenty of capacity for the intermediate storage of steel components. „With  the new preservation line and the resulting further steel processing and refinement possibilities we can fulfill customer requests faster and more efficiently. This helps to reduce our lead times. In addition, the new line, in combination with the roller conveyors and cross-transport systems, improves our logistical setup with shorter walking distances for our employees and streamlines our entire workflow,” concludes Mike Barz.