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Moisture measuring and control systems for sand coolers

Cooler turned into a sand regenerator

Equipped with a moisture measuring and control system a cooler becomes a sand
regenerator.

Optimum sand reconditioning commences in the sand cooler

Properly prepared well-flowing moulding sand at the moulding machine and short cycle times are two important and typical requirements

of modern sand casting production. For good regeneration of the used sand and consistent moulding sand quality at the moulding machine not only a good cooling effect is indispensable, but also sufficient pre-moisturising and a sufficiently long dwell time in the downstream used sand hopper.

Maximum moisture with maximum accuracy – with no fear of over-moisturising

The moisture of the sand conveyed from the cooler to the used sand hopper, should amount, at least, to 2.0 to 2.2% H2O (better more). The importance of this will be explained in the following chapter.

When hoppers and conveyor belts are in optimum condition, some foundries will even operate with ideal 2.8 to 3.0% H2O, which at the same time is affecting the cooling performance positively. A basic prerequisite for this is a reliable moisture measuring and control system, like the MICOMP series, which will convert a fluctuating input moisture level into a consistent output moisture level within very close fluctuation limits. The often met procedure in foundries to operate the process with too dry sand coming out of the cooler as a precaution, because fearing the consequences of over-moisturization, and thereby to tolerate inferior sand quality and higher temperatures is typical for other moisture measurement systems. Such a compromise is no longer necessary with the Michenfelder system. The system is keeping the fluctuation margin at the cooler exit to incomparably low ±0.05 to 0.2%*.

 

Experience and the advanced technology of continuous moisture measurement inside the cooler are the determining factors. 500 – 600 mixer-coolers of all commercial makes have already been equipped with great success. The system is setting the standard since many years.

*1st Standard deviation

Users of fluid bed coolers know the problem well:

Extreme fluctuations of output moisture occur in many production periods, particularly after work breaks or plant standstill

and result in quality deterioration of the moulding sand and of the casting itself. Casting scrap caused by this kind of difficulties does not need to happen. The moisture measuring and control system by Michenfelder ensures across all production periods fully automatically and reliably precisely and sufficiently moisturised moulding sand – and this also when the sand is cold and dry at the start of production or after breaks.

Property-decisive fine dust parts remain in the system

Typical occasions, when other systems fail, for instance with cold (at shift start), very hot or sand from non-cast moulds

are handled by the MICOMP 5 Type G-FBK unit in a targeted manner. In this way, property-determining fine dust parts remain in the sand. Hence, the system provides ideal conditions for early dispersing of the bentonite in the downstream used sand hopper.

Water addition which is only temperature controlled is not sufficient

The installation of a moisture control which is solely based on the temperature of the moulding sand is no reliable solution,

because there are too many critical situations in the production process which remain unconsidered. In case of cold, dry sand, for instance, a solely temperature-based moisture control system would add no water at all (for instance at production start on Monday morning). In such a case the exhaust air system would extract important finedust components, changing the sand characteristics, which again would affect gravely the quality of the casting.

Top solution for batch type coolers

With MICOMP 5 Type G-CHC Michenfelder is providing a system which will provide a highly precise output moisture even in case of widely fluctuating input parameters and considerable amounts of required cooling and moisturising water.