SW MAY 2021 WEB | Page 58

PRODUCTS & PROCESSES
an ultra-high frequency pulsating water jet after exiting the nozzle . This imparts a much higher kinetic energy to the jet , such that it reliably and reproducibly eliminates silicate and weld spatter as well as scale and smoke residues from the surfaces in a clearly defined operating window . Feed rates of up to 800 mm per second are possible , with a robot moving either the workpiece or the nozzle tool .
The part is also cleaned at the same time the welding residues are removed , thus dispensing with the need for an additional cleaning step and the corresponding machine . This not only noticeably decreases investments related to the cleaning process , but also ensures more competitive unit costs because operating costs are significantly reduced . Another factor contributing to the high economic and resource efficiency of the process is the effective treatment of the process water , which is mixed with
a corrosion protection medium so that it can be recirculated for a long time .
Selectively cleaning external and internal geometries
The effective range of the water jet can be precisely adapted to the application by using different nozzle geometries , for example fan and solid-jet nozzles as well as lances . Among other things , this enables not only the outer but also the inner contours of the integral subframes to be selectively cleaned , in contrast to conventional jet-cleaning processes with abrasives .
Process engineering and validation in Technology Centre
The process parameters , such as nozzle geometry , pressure and feed rate , were precisely adjusted using a special test set-up at the manufacturer ' s Technology Centre in Monschau . To validate the new water jetting process , integral subframes were coated in the cathodic dip painting line cleaning and then subjected to a lengthy salt spray test . The results were impressive : The weld seams were cleaner after treatment with the pulsating water jet than after blasting with abrasive media , and any discolouration from the welding process still visible on the surface had no effect on the quality of the paint finish . The high corrosion protection requirements had been met . The new cleaning solution also proved to be a good choice in terms of cost / benefit .
Fully automatic jetting , cleaning and drying in 50-second cycles
In order to implement the developed process in a fully automated machine concept , an integral subframe had to be jetted , cleaned and dried within 50 seconds . To meet this requirement , the cleaning machine has three independently functioning jetting modules with integrated manipulator , a hot air dryer , one robot each for loading and unloading , and a bath treatment unit for the process water .
Pallet cages loaded with several integral subframes to be processed are transported to the machine . The machine ’ s loading robot picks up the parts and places them on the transfer stations of the jet modules . The manipulator of the respective module picks up the part and moves presents in a defined sequence it to the jet tool , treating the welding contours in a specific manner . After cleaning , the manipulator places the integral subframe a clean surface . From here , the loading robot takes it to the drying step . On exiting the dryer , the subframe is picked up by the unloading robot and hooked into the rack for painting .
To eliminate the transport path between the welding and cleaning process , the EcoCbooster can also be connected directly to the welding cell .
The vehicle manufacturer has been using the new cleaning system in series production since mid-2020 . Due to the optimizations achieved , the company is now considering integrating the new cleaning solution into further production lines for integral subframes .
Telephone : + 44 ( 0 ) 7799 346 611 Email : cooper @ ecoclean-group . net Visit : www . ecoclean-group . net
56 MAY 2021 read online : www . surfaceworld . com