Seven Steps to Solving Tabletting and Tooling Problems---Step 3: Repair

Carrying on from our weekly column to help you eliminate a number of tablet manufacturing problems and tablet tooling failures with a simple seven-step tool-care process, we look at the third step, Repair. This is part of I Holland’s PharmaCare seven-step process for tooling maintenance.

Step 3: REPAIR


Light surface wear, corrosion, and minor damage on tooling can be repaired and re-worked to a useable condition. Worn tips can result in poor quality tablets and inferior embossing definition, this can lead to picking and sticking. Equipment such as a motorized chuck and double ended polishing motors are used in conjunction with abrasive polishing accessories. Repair should be carried out by well-trained and experienced maintenance technicians to ensure that the tooling does not exceed tolerance limits. Repair should not be carried out on any coated tooling as this may remove the coating from the punch.

If the damage is only slight, it may be possible to use Step 3 to repair the damage, removing any burrs and re-working the tip edges to a good useable condition, ensuring consistent tablet appearance. If it is found that there is head wear to the punches and for example the head ‘dwell’ flat, which is in contact with the pre-compression and main compression rollers, any light wear can be removed using mildly abrasive materials followed by remedial polishing through Step 3. This should then be followed by measurement of the critical working length during the measurement stage, Step 4, which we will discuss next time.

When in a new condition, the surfaces of tablet punch faces are usually polished to a high mirror finish; however, these can deteriorate over a period of time due to the continuous compaction of granules. This deterioration can lead to tabletting defects such as ‘picking’ and ‘sticking’ brought about by adhesion of the product to the now rough finish. This deterioration can be identified during assessment (Step 2: Assess), the granule can then be cleaned off with an efficient cleaning system (Step1: Clean), and the finish can be improved or repaired by using a remedial polishing process and finished using the automatic polishing method to be outlined in Step 5. Any repair work should be followed by Step 4: Measuring, which is essential after repair to ensure that critical tooling dimensions have been maintained within an acceptable working tolerance. We will look at this in the next issue.

Andy Dumelow is PharmaCare manager at I Holland.