Flowability

Flow characteristics of liquid and granular substances.

In contrast to Fluidityflowability (in the foundry engineering-related meaning of the word) defines the capacity of a molding material to shift and relocate under the effect of a compacting force so that a mold with varying geometrical ratios displays a more or less uniform density associated with uniform distribution of properties along all areas and sections. This definition applies, regardless of the determining type of flowability for homogeneous density distribution; i.e. free flowability during pouring or flowability under stress during compaction.

Among the numerous technological methods for measuring of flowability, specification of flowability according to Orlov is of great significance, particularly with regard to analysis of the compaction process and achievable mold quality. Orlov defines the flowability of a molding material as the material’s capability for compensation of variations in compressive stress within the mold through lateral flow.



Figure 1
illustrates the testing facility according to G. M. Orlov. For this purpose, a standardized test specimen is used. It is inserted into a 25 mm high unit representing the pattern. Compaction, particularly the parameters of kind and intensity, is adjusted to operational conditions. For comparison, a compressive force of 1.0 Mpa is used. After pressing, the mold hardness is measured on the surfaces a and b and flowability is calculated according to Eq. 1 .



Eq. 1:


Another procedure is the GF flowability test (Fig. 2). It is performed using a conventional test sleeve that is equipped with a flange-like widening at the bottom. A type of sand with good flowability will divert into the flange. To determine the test results, the height (h) that the sand test specimen reaches under the given compaction.

From the heights (h1) for flowability = 0 % and (h2) for flowability = 100 %, flowability for the measured height (h) is calculated according to Eq. 2.



Eq. 2:


Additional references:

 

  • Fig. 1: Flowability acc. to Orlov (source: S. Hasse, editor of Gießerei-Lexikon, Schiele und Schön, publishing house for technical literature, Berlin
  • Fig. 2:  GF flowability test (suelle: S. Hasse, editor of Gießerei-Lexikon, Schiele und Schön, publishing house for technical literature, Berlin
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