Relation between Ammount of Binders and Permeability

Abstract

  Permeability of molds is affected by sand grains, binders and ramming. The author analyzed the permeability by there factors and worked out a way to construct the permeability from this analytical result.
  That is : the permeability is computed by the following formula as :
                    F=K₃×K₂× Σ(f_n×W_n)⁄ΣW_n
  where:   F=permeability
              K₃= constant, refer to packing
              K₂=constant, refer to binder
              f_n=coefficient of permeability (=K₁D_n²)
              K₁= constant, refer to grain size
              D_n= mean diameter of sand grains
              W_n=percent of sand grains retained
  In this report, the author investigated how the permeability would change with the amount of binders. K₂ is the ratio (a_x/K₁) of a_x and K₁ ; the former (a_x) is a tangent of permeability and D_n² when the amount of binder is changed, and the later (K₁) is a tangent of permeability and D_n² when a resin is used as a standard binder. Now, if the same sort of binder is used and only its additional amount is changed, a_x is to be a constant as to a certain additional amount of said binder, Consequently, K₂ can be determined by a_x and K₁.
  Those rusults of permeability for green and synthetic sands which were computed by using K₂ agreed very well with the measured results.