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14 Pharmaceutical Technology TRENDS IN MANUFACTURING 2022 eBOOK P h a r mTe c h . c o m Solid Dosage flat), crucial for tablet weight and thickness. Over- all length is another key measurement. This is the nominal reference length or total punch length from the head flat to the edge of the punch tip. It is essential to measure at regular intervals dur- ing production. Tooling will wear, and this can lead to inconsistences in overall and working punch lengths across the set. New tooling should also be measured to verify specifications and ensure it is correct before use. Don't assume that because it is new it is correct. Tools should also be measured after any repair work as this can affect tablet weight variation. Tab- let weight measurement is a universal tablet quality control parameter to ensure the correct dosage of medicine is contained in each tablet. Non-uniform or excessive variation in punch working lengths is one of the more common causes of tablet weight variation and should be monitored closely. If weight control is critical, upper and lower punches can be measured and matched to minimize dimensional variation. Finishing touches Correctly polishing tooling helps to maintain a suitable surface and restore the optimum finish to prevent problems like sticking or picking. This step can also remove light corrosion and help to repair small amounts of damage and abrasion that have occurred during production. The correct polishing method is crucial to ensure that the embossing definition is maintained. Prob- lems with embossing are largely caused through abrasion, which appears in a series of scratches to the tool face and is the result of frictional forces ap- plied to the tooling surfaces. Over polishing, or the use of incorrect materials during the process, can adversely affect tooling and cause a lack of emboss- ing definition. Routine polishing can help to restore edges of the embossing, maintain the profile over a longer pe- riod of time, and improve surface finish. Light polishing should be performed on a frequent basis and after every campaign. It can be achieved through manual or automated methods but due to the controlled and repeatable process, adoption of an automated polishing regime would always be Figure 4. If the granule being compressed is particularly hard and abrasive, the tooling will wear faster. Figure 5. Repairing coated punches increases the risk of compromising the functional performance of the coating.