Compaction and compression_2

Views:
 
Category: Entertainment
     
 

Presentation Description

No description available.

Comments

Presentation Transcript

Seminar on…:

Seminar on … Compaction & Compression Presented By … Saiesh phaldesai

CONTENTS :

CONTENTS INTRODUCTION COMPACTION & IT’S PROFILE PROPERTIES AFFECTING COMPACTION DISTRIBUTION OF FORCES MEASUREMENT OF FORCE EVALUATION OF COMPRESSION BEHAVIOUR RECENT DEVELOPMENT REFERENCES

INTRODUCTION :

INTRODUCTION Compaction generally utilized for Tablet manufacturing from Powdered material. Many Compression Instruments are developed such as Single punch, Multiple punch, Rotating Punch etc. Now, A lot of works has been done to provide Tablets with better Compactibility & efficacy.

COMPACTION :

COMPACTION Definition of compaction Compaction of powder is general term used to describe the situation in which these materials are subjected to some level of mechanical force. Physics of compaction may be simply stated as compression & consolidation of two phase (particulate solid –gas) system due to applied force .

PowerPoint Presentation:

Definition of Compression. Compression means a reduction in the bulk volume of the material as a result of displacement of gaseous phase. Definition of consolidation. Consolidation is an increase in the mechanical strength of the material resulting from particle/ particle interaction

COMPRESSION:

COMPRESSION When external mechanical force is applied to a powder mass there is reduction in bulk volume. The onset of loading is usually accompanied by closer packing of powder particles. As load ↑compression involves particle deformation.If deformation is reversible like rubber than said to elastic. ex ;acetylsalicylic acid &mcc shows elastic deformation. if elastic limit or yield point is reached then deformation is irreversible it occurs when shear strength< tensile strength. If shear strength > tensile strength then result in brittle fracture.

CONSOLIDATION:

CONSOLIDATION COLD WELDING: When the surface of two particles approach each other closely enough their free surface energy result in strong attractive force process know as cold welding FUSION BONDING:. On force application heat generated within the die,if not dissipated the local rise in temperature could be sufficient to cause melting of contact area of particle. The melt solidifies giving rise to fusion bonding. Factors Effecting Consolidation: The chemical nature of material. Extent of available surface Presence of surface contaminants

PowerPoint Presentation:

Powder compaction technology A theoretical target is to achieve the same density all over the compact, in practice, a density distribution as much uniform as possible. Even with a simple shape (a cylindrical part as drawn on next slide) , the density in the compacts will not be uniform. The density distribution is mainly a function of: the friction forces between the powder and the die the compacting action of the punches Using lubricants, you are able to reduce the effects of the friction forces.

PowerPoint Presentation:

Using a double acting press or a press with a floating table, you are able to manufacture compacts with a better density distribution (see picture on the left). As a result of this, even in these simple compacts the density distribution will not be the same. Powder characteristics Some of the main characteristics to be known before the compaction of any kind of powder are: flowability compressibility diagram friction forces distribution in the die

PowerPoint Presentation:

When the average tablet hardness is plotted against the average compression peak force, we get the so-called compaction profile that allows us to compare different formulations or different processing speeds. On the screen, which formulation is better? Well, formulation No. 2 makes harder tablets for the same compression force, and this would mean less wear and tear on the production press is required to achieve desired hardness. On the other hand, if your hardness tolerance limits are exceptionally narrow, the steeper slope of formulation No. 2 may be a detriment.

FORCE DISTRIBUTION THROUGH POWDER BED:

FORCE DISTRIBUTION THROUGH POWDER BED Consider a group of particles in a die of an eccentric tablet press. Significant features are zone of high force at the periphery near the moving punch &much lower in powder mass on its vertical axis Low forces zone occur on the same axis but much nearer moving punch

PowerPoint Presentation:

Consequence of this on tablet strength can be found:- Particle deformation whether plastic or elastic will be proportional to applied force The porosity of tablet &hence its strength The weakest points in tablet structure will be those that receive the lowest forces F A =F L +F D

PowerPoint Presentation:

F A = force applied to the upper punch. F L = proportion of it transmitted to the lower punch F D = reaction at the die wall due to friction at this surface . F M =F A +F L /2 where FM = mean compaction force .

Measurement of force :

Measurement of force Instrumentation - Strain gauge . Siting the strain gauge . Strain gauge instillation. Wheatstone bridge circuit Method – Done by instrumented tablet machine. Strain gauge are attached at various parts of the press. If force is applied to the punch it deforms, the magnitude of deformation being governed by applied force & value of Youngs modulus for the punch.

PowerPoint Presentation:

An instrumented eccentric press is given below -

Compactibility :

Compactibility Definition :- The ability of powder bed to cohere into or to form a compact. Properties of powder related to vol. reduction & compact strength – Particle dimensions. Mechanical properties (crystalline or amorphous). Granule properties.

PowerPoint Presentation:

PROBLEMS RELATED TO COMPACTION:- Low mechanical strength of tablet. Capping & lamination. Adhesion or sticking of material to punch tips. Weight variation.

Evaluation of Compression:

Evaluation of Compression Two types, Characterization of ejected tablet : By inspection of tablet:- e.g. scanning electron microscopy. b. By pore structure:- e.g. gas adsorption method. c. By surface area:- e.g. air permeametry method.

PowerPoint Presentation:

Characterization of compression & decompression events. Force displacement profile.

PowerPoint Presentation:

Heckel Equation, In (1/E) = kP + A E = tablet porosity P = applied pressure A = constant k = slope of linear part of relationship.

Roller Compaction :

Roller Compaction Used to densify the material to enhance its flow properties & improve content uniformity Advantages:- Doesn't require water during processing USE:- To improve processibility of moisture sensitive materials Disadvantage:- Loss of reworkability

DIRECT COMPRESSION :

DIRECT COMPRESSION This technique is being applied for many non crystalline materials too Excipients, MCC, EC ,metal phosphate and carbonate. properties for direct compression material High bulk density. High compressibility . Low hygroscopicity. Good flowability.

PowerPoint Presentation:

Cold press facility Cold pressing offers rapid production of materials from powder, and usually follows mechanical alloying. The technique is simple, quick and facilitates preparation of materials which may not be possible using conventional melting techniques. After cold pressing, the samples are usually sintered. Hot vacuum press facility Although a slower process than cold pressing, hot pressing can produce better materials with higher density and chemical bonding. The system operates under vacuum to 10-5 Torr, with maximum temperatures above 1000K and pressures of 200MPa.

PowerPoint Presentation:

Development of A Predictive Model for Ceramic Powder Compaction Figure 2. The density gradients predicted in a cermet source feedthru after biaxial pressing. A low density area (yellow) appears between the vias when the material within the vias is incompressable.

References:

References THE THEORY AND PRACTICE OF INDUSTRAIL PHARMACY BY LEON AND LACHMAN 3 rd edition Pharmaceutical powder compaction technology by claw forher masel deckker TABLET MACHINE INSTRUMENTATION IN PHARMACEUTICS BY PETER REDGWAY WATT REMINGTON THE SCIENCE&PRACTICE OF PHARMACY VOL 1 ST ,19 TH EDITION JOURNAL OF PHARMACEUTICAL SCIENCE VOL 96 MAY 07 PHARMA TIMES VOL 29, NO 2 FEB 07 www.google.com

PowerPoint Presentation:

Thank you...

authorStream Live Help