 SPC 40.20 is so far the largest cleaning plant. |
 The operator may observe cleaning through the windows. |
 Simulation of spraying ensures successful cleaning. |
The economy of mould spraying in the production of light metal high pressure die castings depends on the defined combination of cooling, lubrication and separation. Main criteria for the precise control are concentration, spray time, direction of spray as well as amount of agent and its distribution on the mould surface. The most important partner in this context is the atomizer or spraying tool. Its design, adjustability and atomizing method exert significant influence on the control of the entire spray process.
Prime adjustments are generally undertaken with new or clean sprayers in order to establish a defined starting situation for future statistic quality comparison and to enhance repeatability of the initial casting quality. Liquid separating agents are usually composed as emulsions of the active substances in water which are to rapidly disintegrate on contact with the mould. Thus they are, more often than not, of limited resistance against the mechanical stress during conveyance through pipe lines, valves, diaphragms, throttles and nozzles. These may be subject to gradual flow reduction due to internal encrustation caused by agent residue. Subsequently, throughput of separating agent is reduced and the initially chosen prime adjustment is lost on account of the castings’ quality.
Hitherto the sprayer had to be taken apart and all its components be washed in order to remove the internal encrustation. After cleaning and re-assembly of the sprayer the individual nozzles would have to be adjusted again to re-establish the initial quality level. Cleaning intervals may vary significantly depending on e. g. casting parameters und the composition of the release agent. Since 1998 GEILERT ENGINEERING at Schwalmtal/Lower Rhine, Germany, has been dedicated to this problem. Result of their endeavour is a system of plant allowing the sprayers to be cleaned internally without the necessity of taking them apart. As one result the initial adjustment of the sprayer is maintained. With their water-based cleaning solution, the spraying performance may be simulated in the plant, and the operator is enabled to test the success of the cleaning process immediately. He will, in addition, detect and localize defective seals, O-rings and spray nozzles and replace them on the spot. With this cleaning system the item »scrap casting by spray failure« may be eliminated from the quality agenda. Numerous plants have been supplied already to European foundries. Market requirements led to six different sizes of plant which are orientated on the sizes of die casting machines. During the course of 2009 two machines of the model SPC 40.20 – so far the largest – were supplied to customers in Austria and Germany. (Photo 1) Its available volume is 1800x1800x1000 mm (LxWxH)
The encrusted sprayer is moved from the casting bay to the cleaning plant by means of a forklift and placed upon the hydraulic lifting table. It is then raised in order to be connected to the adapter of the plant. After this the sprayer is moved electromechanically into the cleaning chamber, and the doors are hermetically closed. The pre-warmed cleaning liquid is pressed through the sprayer by a centrifugal pump. Internal sediments of the release agent are gradually resolved chemically and thermally. The cleaning solution leaves the sprayer through the nozzles together with the encrustation and is collected within the plant chamber. Generously sized windows allow the cleaning process to be observed (Photo 2) as well as the ensuing spraying simulation to witness the cleaning results (Photo 3). Life time of any one bath solution may reach up to six months depending of the degree of contamination of the sprayers cleaned.
Plants are designed and built at Schwalmtal. GEILERT ENGINEERING has entered into a cooperation with FIMRO GmbH, Langenstein, in the field Sales and Service.
Uwe Geilert, Ph.D. (Proprietor), Geilert Engineering, Schwalmtal
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