Uniformity differentiation analysis. Part 2: Powder deposition characteristics in circular shallow die using feed shoe with circular cross section

Since dies of different geometry are used routinely in industry, the second-generation pressure deposition tester (PDT-II) was used to investigate powder deposition characteristics into a 6.5mm deep circular die that complements the 6.5mm rectangular shallow die result in Part 1 of the article. Two types of powders, namely, microcrystalline cellulose (Avicel PH102) and a battery powder mixture (BPM), with median size of 84 and 600m, respectively, were used as test materials. Symmetry analysis, variance metrics, and uniformity analysis were used to quantify the deposition characteristics. The results showed that: (1) die shape greatly influenced the uniformity of pressure distribution inside the die; (2) the uniformity of pressure distribution increased with increasing feed shoe speed; (3) the back and forward regions filled faster than the front and leeward regions; (4) the front and leeward regions showed greater uniformity of pressure distribution than the back and forward regions; (5) the areas of high pressure values (above 60dm) were less than 5% of the total; (6) the circular die generated a higher uniformity inside the die than the rectangular die for both Avicel and BPM; and (7) the rectangular die generated a higher stress concentration zone inside the die than the circular die for both Avicel and BPM.