Journal of the American Ceramic Society, Vol.90, No.6, 1780-1786, 2007
Industrial quantitative control of the pressing behavior of spray-dried MnZn-Ferrite granules
In the first stage of a broad factory stabilization program, the compaction properties of spray-dried granulated powders are investigated. Certain compaction process parameters are identified and include (i) the slide coefficient between powder material and die wall during compaction, which mainly affects the pressing tool life time, (ii) the ratio of the pressure drop over the compact to the axial mechanical strength of the compact, basically related to the chance of chipping and crack occurrence upon ejection, and (iii) the homogeneity of the density profile along the compact, basically related to the chance of crack development and product deformation during sintering. The effect of important factors, such as binder and lubricant content, granulate storage humidity, and compaction temperature, on those parameters is investigated. Based on factory data, specification values for the previously mentioned parameters are derived and used to control the compaction quality of the industrially spray-dried powders with satisfactory results.