Double Impression in Tablets

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Double Impression in Tablets

1.10.1.9

Double impression in Tablets and Solution

(1)

Definition: 'Double Impression' involves only those punches, which have a monogram or other engraving on them.

Reason: At the moment of compression, the tablet receives the imprint of the punch. Now, on some machines, the lower punch freely drops and travels uncontrolled for a short distance before riding up the ejection cam to push the tablet out of the die, now during this free travel, the punch rotates and at this point, the punch may make a new impression on the bottom of the tablet, resulting in 'Double Impression'.

If the upper punch is uncontrolled, it can rotate during the short travel to the final compression stage and create a double impression.

Table.42. The Causes And Remedies Of Double Impression

Sr. No.

CAUSE

REMEDIES

1.

Free rotation of either upper punch or lower punch during ejection of a tablet.

-Use keying in tooling, i.e. inset a key alongside of the punch, so that it fits the punch and prevents punch rotation.

-Newer presses have anti-turning devices, which prevent punch rotation.

About the Author

Dr.Mukesh Gohel's picture
Author: Dr.Mukesh Gohel

Dr. Mukesh Gohel is principal, professor at the LMCP, Ahmedabad served in academics for more than 40 years. He provides training in leading pharmaceutical industries in the areas of Design of Experiments and Quality by Design. His current areas of interest are direct compression and improvement of drug dissolution.

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