Mold material control

Controls the composition and therefore the properties of bentonite-bound mold material systems (bentonite sands). In this way, mold material control can compensate for quality deviations in the mold material due to continuous monitoring and testing of the mold material circulation (s. Mold sand testing). The parameters and variables measured during mold material testing are linked and compared with the reference value (casting quality).  

The most important methods used for this purpose are listed below:

1. Conventional testing technologies
On the basis of specified intervals, the molding material properties measured at specimen are compared with the technologically defined values and manually corrected in the molding material circulation, as required. The disadvantage of this method is that it is not suited for wielding influence on the entire process and temporary variations cannot be taken into account. However, this type of control is capable of ensuring consistency of the molding material properties within the specified limits for conventional molding processes. 

2. Use of computing equipment (offline)
With this method, mold material testing is also performed manually and with a certain time lag compared with production. However, due to the use of computers it is possible to link the apropriate algorithms in the form of influential and reference variables with each other.  Reaction with regard to deviations takes longer periods. This type of mold material control is preferably used in production systems with low to medium process dynamics.

3. Preventive molding material control
In this scenario, control operations that are deduced from process data (e.g. sand-iron ratio or thermal loads of the molding material) are performed preventively for anticipatory control, i.e. before the occurrence of changes and modifications in the molding material quality. Material control is generally performed by means of computers and allows for calculation of individual addition rates of components such as bentonite, carbon dust, new sand. In this way, the test effort is more an more shifted from mold material testing to acquisition and implementation of process data. 

4. Mold material control with the help of automatic data acquisition (online)
State-of-the-art automated mold systems with requirements for high and consistent mold material quality and options for immediate response to changes in the recirculation system make automated data acquisition, computer-controlled data analysis and corresponding output of dosing signals mandatory conditions (datec Dosier- und Automationstechnik GmbH).

It is particularly the options for automated data acquisition, control of mold material moisture, and definition of used mold material quality (residual water content, temperature, activated clay, sediment contents) that must be strongly emphasized.

Additional references:

Mold material balance
Mold material management
Mold material recovery
Sand conditioning
Sand regeneration