Gran-U-Lizer. The Gran-U-Lizer is a nonattrition size-reduction mill. It uses roller-mill technology that contols particle-size reduction
through roll-surface texture (i.e., roll type), roll speed, and roll gap. According to MPE, the Gran-U-Lizer operates through
the use of shear, in contrast to impact used by conventional size-reduction equipment. The Gran-U-Lizer achieves a narrower
particle-size distribution with fewer fines by eliminating the attrition inherent in other milling designs. The laboratory
model Gran-U-Lizer requires several passes through the rolls using various roll types, roll speeds, and roll gaps to achieve
the desired particle-size distribution. All milling trials using the Gran-U-Lizer roller mill were conducted at MPE's Chicago
Table I: Microcrystalline cellulose–dibasic calcium phosphate (2:1) placebo formulation.
Two IR, dry-granulation placebo formulations (see Tables I and II) were selected to evaluate mill performance. Roller-compaction
conditions were established using the Gerteis Mini-Pactor roller compactor to produce ribbon at a target solid fraction of
0.7 at an approximate thickness of 2.5 mm. Ribbon was manufactured from both formulations and characterized for solid fraction,
tensile strength, and thickness. Roller-compaction bypass was measured to establish the fines level within the compacted ribbon
Table II: Microcrystalline cellulose–lactose (2:1) placebo formulation.
Ribbon samples were prepared by cutting the compacted ribbon into rectangular shapes of approximately 10 x 22 mm using a
jeweler's table saw. Figure 1 demonstrates how the ribbon sample was prepared. The cut ribbon sample was measured using calipers
to determine the envelope density.
Figure 1: Measurements of ribbon dimensions. (AUTHORS)
The solid fraction of each ribbon sample was determined according to a relationship that can be expressed by the following
in which w is the ribbon width, l is the ribbon length, t is the ribbon thickness, m is the ribbon mass, V
is the volume of the roller serrations, and ρ
is the true density of the material.