Size reduction

Size reduction

1. SIZEREDUCTION
Suraj Mandal
Assistant Professor,
M. Pharm (Pharmaceutics)
Pt. Rajendra Prasad Smarak College
of Pharmacy, Puranpur

18. VARIOUS
EQUIPMENTSUSE
INSIZEREDUCTION

22. ADVANTAGESOFHAMMERMILL
•Itisrapidinaction,andiscapableofgrindingmany
differenttypesofmaterials.
•Theyareeasytoinstallandoperate,theoperation
iscontinuous.
•Thereislittlecontaminationoftheproductwith
metalabradedfromthemillasnosurfacemove
againsteachother.
•Theparticlesizeofthematerialtobereducedcan
beeasilycontrolledbychangingthespeedofthe
rotor,hammertype,shapeandsizeofthescreen.

23. DISADVANTAGES
•Heatbuildupduringmillingismore,
therefore,productdegradationispossible.
•Hammermillscannotbeemployedtomill
sticky,fibrousandhardmaterials.
•Thescreensmaygetclogged.Wearingofmill
andscreenismorewithabrasivematerials.

24. BALLMILL
•Thesearealsoknowsastumblingmills.
•Principle:Theballmillworksontheprincipleof
impactbetweentherapidlymovingballsandthe
powdermaterial,bothenclosedinahollowcylinder.
•Atlowspeeds,theballrollovereachotherand
attrition(rubbingaction)willbethepredominate
modeofaction.Thus,intheballmill,impactor
attritionorbothareresponsibleforthesize
reduction.

28. Advantages:
•It canproduceveryfinepowder.
•Ball mill is used for both wet and dry grinding
processes.
•Toxicsubstancescanbeground,asthe cylinderis
closedsystem.
•Rodor barscanalso beusedas grindingmedia.
•(example:Stickymaterialaresizereduced)Inballmill,
•installation,operationandlabourcostsarelow.

29. Disadvantages:
•Theballmillis averynoisymachine.
•Ballmillisaslowprocess.
•Soft,tacky,fibrousmaterialcannotbemilled
byballmill.

32. The Disintegrator
Principle-ThesizereductionindisintegratorisdonebyImpact.
Construction-
Itconsistofasteeldrumhavingashaftinthecentre.
Theshaftcontainsadisc,onwhich4beatersarefixed.
RotationSpeed-5000-7000RPM
Sideanduppersurfaceofthedrumisroughandundulating.
Thelowerpartofthedrumhasdetachablescreenorsieve(definiteporesize).
Working-
Thebeatersaremainlyresponsibleforgrindingbutarehelpedbytheundulation
oftheinnersurfaceandroughnessofdrum.
Thematerialisfedtobeaters,throughhopper.
Materialsarebrokenbyimpactofthebeaters.
Duetohighvelocityofbeaterstheairvelocityinsidethechamberisincreased.
Theairisallowedtopassthroughanoutletonwhichdustbagistied,which
retainsthefineparticlesofpowder.

33. Diagram of Disintegrator in section
Use-
The Mill is used to powder all
type of drugs including very
hard drugs.
The drug should be dried before
feeding into the disintegrator to
get fine powder.