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State-of-the-art painting technology for large construction machines in the Ott painting centreModern painting technology makes for time-saving processes and lower material consumption.

For painting large construction machines, the Ott painting centre is investing in a new paint supply installation and is modernising the paint shop at the same time. The switchover to the new technology has resulted in a marked reduction in solvent emissions. Modern painting technology makes for time-saving processes and lower material consumption.

When painting is involved in the Ott painting centre, the painting professionals are dealing with large dimensions. Mobile truck cranes for instance are therefore being painted for the Liebherr works in Ehingen. Other large vehicles such as buses, excavators and construction machines are also being painted too however by an experienced team in the special paint shop 7 m wide, 33 m long and 20 m high using state-of-the-art equipment and methods.

When an eight-axle LTM 1500-8.1 mobile crane from the Liebherr company needs painting, this is no small feat already in terms of painting. With a dead weight of 96 t and a jib 84m long, the LTM 1500-8.1 numbers among the largest in its class and the painting work must nevertheless be performed carefully and scrupulously. One can easily imagine the sheer volumes of primer and paints that need to be processes for the surface coating of vehicles of such large dimensions. Until the switchover to the new paint supply technology, the paints were mixed manually and processed by means of a large pump - a tremendous potential for savings through electronic mixing technology and for harmonisation with current environmental regulations.

Reducing the rinsing processes cuts down solvent consumption

The Ott painting centre works with high-solid primers and top coat. In the new central colour supply, the standard materials are stored 200l drums. The containers are level monitored in order to avoid undesirable breaks in production. Six Flowmax pumps (bellows pumps) from Kremlin convey the primer, hardener and paints to the mixing console in the paint booth. According to Peter Hornschuh, the project manager of EXEL Lackier- und Beschichtungssysteme GmbH: “the saving results from the provisioning of the standard colours. This is noticeable above all during rinsing, as rinsing of the lines is completely dispensed with”. Solvent consumption has decreased by approx. 30 per cent of the previous volume. According to Oliver Trowitzsch, the authorised officer in the Ott painting centre: "we now only need smaller quantities of solvents, a major saving in comparison to the earlier situation”. A further effect is the dramatic reduction in hazardous waste and the associated high disposal costs.

Mixing and metering system for highest demands

Formerly, major wastage of time and materials occurred as a result of manual metering and mixing of the components for the coating. The mixing and metering unit (Cyclomix Expert) from Kremlin takes charge of this task in the new installation. This multi-component system is designed for electronic mixing and metering of 2 and 3-component materials. It is capable of processing 15 colours and three different hardeners. Fifty formulas can be stored in the controller, with each colour being assigned its own program for mixing ratio, processing time and rinsing process. The electronic controller memorises ten different rinsing programs for colour change, plus an additional weekend rinsing program. The installation is controlled using a touch screen, which is simple to handle in spite of the many possible inputs. The display indicates among other aspects the consumptions of the colour and hardener containers. The control program also records the consumption of organic solvents according to the VOC directive.

Dyeing of the filler using 3-component technology

The installation has been expanded into a 3-component system, an option that additionally economises on material above all through dyeing the filler in the colour in which the object to be painted is actually to be painted. The electronic controller automatically admixes up to 10% vol. proportions of the top coat with the filler and therefore a 3-component material is involved in this case. This results in lower top coat consumption since the colour covers considerably better on the dyed filler. The control and mixing console can be separated for use in explosive zones. Whilst the switch cabinet remains outside the explosive zone, the mixing console with the mass flow rate meters is installed in the booth, which - owing to shorter hoses – further reduces detergent requirements. The control commands are transferred to the explosive zone by means of a cable. The installation is equipped with Profibus interfaces for integration in a supraordinate controller and the installation can be connected to the operating data network, so that all data are available in real time and can be archived.

New Xcite AirMix sprayguns for fatigue-free work

The primer and high solids are applied using the so-called Airmix method. In so doing, the spray medium is atomised with pressure and air. This allows very uniform application with a relatively low material pressure - upwards of approximately 60 bars, depending on the material. An additional air jacket shapes the spray jet and reduces overspray. This economises up to 25 per cent of material in comparison to the conventional airless method. The Airmix system with a new, optimised airflow of the Xcite HVLP guns ensures fine and even atomisation, reliable coating results and a high surface quality. The Xcite Airmix gun has been specifically designed with regard to fatigue-free work. In addition to the ergonomic design, the trigger and holding forces have been reduced.

New floor with integrated floor aspiration and lighting

Oliver Trowitzsch is satisfied with the new technology. ,”As a result of the investment, we have been able to further improve our solvent balance in order to comply with the statutory provisions. There are considerable savings in terms of time and material consumption”. Through modernisation of the floor in the paint booth, with integrated aspiration and lighting, it was also possible to make a contribution to the occupational safety and health protection of the employees. "The working conditions during chassis painting have markedly improved”, Illija Markotic, a painter in the Ott painting centre reports.

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