Capsule filling studies using an mG2 production machine.

A production mG2 G36 machine has been employed to study the effects of compression on the capsule filling properties of four particle size fractions of lactose having a range of flow properties. The effect of the surface texture of the dosator nozzle bore on capsule filling is also investigated. Fine, cohesive powders gave uniform fill weights over a whole range of compression settings but as increasingly free-flowing powders were used, this range diminishes. For both types of powder, the upper limit on compression is set by compaction of powder which produces poor fill weights; coarse, free-flowing powders, which are less compressible, compact at lower compressions. Free-flowing powders, in particular, also require a minimum compression to be retained. Resurfaced nozzles produced improved capsule filling. One nozzle surface produced slightly more uniform fill weights and was unaffected by powder coating of the nozzle suggesting that an optimum surface texture exists for capsule filling. The results are similar to those obtained using the mG2 simulator and hence validate the latter's use in studying production capsule filling.