The Mould Dryers “MD-35kw / MD-70Kw” is a compact, electric heated for drying of water- or alcohol based coating of resin, betonies or cement sand forms and cores.
ACCESSORIES FOR OUR MOULD DRYERS MD-35KW / MD-70KW Distribution box with two/four outlets, end welding flanges suitable for fixing hose with clips.
DESCRIPTION AND OPERATION:
The mould Dryer “MD-35KW / MD-70KW was developed to save energy . Hot air with a adjustable outlet temperature between 60 and 300 Degree C to the assembled mould after all openings (feeders and gating system) are covered. The hot air escapes through the sand of the mould and the core and dries the coating. Besides, the surface of the mould hollow cavity is steadily warm up. Because the outlet temperature of the hot air maximum 300 Deg C can amount, no crystal water from the cement sand binding agent can be removed, but the coating will be to the same temperature as temperature of the sand surface.
The drying time depends on the thickness of the sand which has to be held heated up and therefore on the medium module of the casting.
With this dry method all sand zones of the mould are dried to guarantee a condition for perfect pouring.
This dry process must be organized according to the pouring time that the dry process of the module should be finished only approx. 30 minutes before pouring. Mistakes are thereby avoided in the cast by humidity and by possible condensation water on the surface of chills.
With entire cooling down the mould it comes by back diffusion of the humidity during pouring or during the solidification to reactions of this moisture with the liquid metal what mistake can originate from (gas defects on the surface). The drying time of the air can be calculated form the surface of the mold, from the wall thickness of the cast and from the heating capacity of a mould dryer. To keep the hot-air temperature very steady with different gas permeability of the mould, the regulation about the ventilating fan speed with the outlet temperature is controlled automatically. Thus the full heating performance of 35 Kw or 70 kw can be fully used without switching off and on the heating registers.
TEMPERATURE SETTING
THE CORRECT USE OF OUR MOULD DRYER MD-35KW / MD-70KW : For flawless MD-35KW / MD-70KW : is the condition that the feeders and the gating system are well covered, so that the hot air is pressed in the mould. With this method coatings with very low gas permeability should not be used. However, all commercial zircon coating are suitable after our experience well.
It is advisable in general to insert commercial sealing strings in the division level of the mould. This should be also used under the steel disks for the welding flanges and the thick disks for covering the feeders.
IMPORTANTLY:
When the mould and/or the cores are fresh coated and the mould is assembled a short time before staring the mould dryer it is necessary to pay attention to the fact that approx. 30 min hot air is blown through the mould one feeder is kept open for this time. A large part of the humidity can thereby escape. The rest humidity is pressed by the produced over pressure into the mould and the cores.