Definition: The term is used when either the upper or lower part of the tablet separates horizontally either partially away from the main body or completely and forms a cap when ejected from the press or during the handling process.
Cause: This happens when air is trapped during the compression stage and when the tablet expands after being ejected from the die.
Table.27. The Causes And Remedies Of Capping Related To 'Formulation' (Granulation)
|1.||Large amount of fines in the granulation||Remove some or all fines through 100 to 200 mesh screen|
|2.||Too dry or very low moisture content (leading to loss of proper binding action).||Moisten the granules suitably. Add hygroscopic substance e.g.: sorbitol, methyl- cellulose or PEG-4000.|
|3.||Not thoroughly dried granules.||Dry the granules properly.|
|4.||Insufficient amount of binder or improper binder.|
Increasing the mount of binder OR
Adding dry binder such as pre-gelatinized starch, gum acacia, powdered sorbitol, PVP, hydrophilic silica or powdered sugar.
|5.||Insufficient or improper lubricant.||Increase the amount of lubricant or change the type of lubricant.|
|6.||Granular mass too cold to compress firm.||Compress at room temperature.|
Table.28. The Causes And Remedies Of Capping Related To 'Machine' (Dies, Punches And Tablet Press)
|1.||Poorly finished dies||Polish dies properly. Investigate other steels or other materials.|
|Deep concave punches or beveled-edge faces of punches.||Use flat punches.|
|3.||Lower punch remains below the face of die during ejection.||Make proper setting of lower punch during ejection.|
|4.||Incorrect adjustment of sweep-off blade.||Adjust sweep-off blade correctly to facilitate proper ejection.|
|5.||High turret speed.||Reduce speed of turret (Increase dwell time).|