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Flashcards in milling and blending Deck (18)
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reason for size reduction

1) increase SA for reaction
2) improve extraction of active principles
3) improve dispersibility
4) allow better mixing or blending*
5) enable rapid dissolution*
6) preliminary process in preparation of productions *

* impt for solid dosage form


what affect size reduction

mechanical- type of equipment
fracture mechanics of particles
properties of material


advantage of wet grinding

1) eliminate dust
2) Easy to handle
3) use less energy
4) increase mill capacity


Disadavantage of wet grinding

1) increase wear of grinding medium
2) not application to soluble material
3) may need drying of product


size reduction process

1) fracture
2) abrasion


factors affecting size reduciton

1) friability range (brittleness)
2) toughness
3) abrasiveness
4) hygroscopicity
5) explosiveness
6) corrosiveness


Size reducion mechanism

1) impact (hammer)
2) compression (roller)
3) shear (knife edge)
4) attration


advantage of hammer mill

1) several models available, verticl and horizontal designs
2) medium to high shear applications
3) blades and screens are interchangeable
4) suitable for very hard materials


disadvantage of hammer mill

1) noisy and dusty
2) cannot plug feed
3) belt slip common due to load
4) high volume air generation, ventilation requirement
5) screen selection and installation complex and not scalable
6) sifting required after milling
7) temperature rise due to friction


cone mill hole for wet dispersion

square hole


round impeller in cone mill for ____--

Dry sizing


squareimpeller in cone mill for ____--

wet and dry sizing


micronization mill

vibratory ball mill
air jet mill
fluid energy mill


loading methods

1) always consistent
2) layering reduces the number of blend revolution
3) layer large volumes of exvipient or active
4) lubricants do not normally require layering and tend to improve flow properties and may help blend cohesive products


essential for excipients and base materials to be within reasonable specifications otherwise it could lead to differing blend parameters

essential for excipients and base materials to be within reasonable specifications otherwise it could lead to differing blend parameters


issues to consider when using vibration IBC

1) compaction
2) segregation
3) noise
4) IBC damage
5) weighing systems
6) dosing capability
7) production residue


blending critical parameter

1) number of revolution
2) % fill
3) loading method
4) sampling method
5) formulation

- simple scale up process
- contained process


NIR benefit

1) safe
2) no sampling error
3) real time information
4) multi ingredient uniformity
5) process understanding
6) process finger - printing for scale up
7) right first time
8) fast release of the blend - reduced cycle times