Issue link: https://www.e-digitaleditions.com/i/1000772
Tablets & Capsules July 2018 37 Beyond proactive maintenance: Resizing tool lengths The critical punch dimension for ensuring consistent tablet production is the working length. Working length is the distance between the surface of the punch head flat and the deepest point in punch cup. The working lengths of each punch in the set must be within the tolerance range determined by internal standard operating proce- dures (SOPs) to ensure that the tablets produced by all the tools in the tooling set meet the required parameters. Visually inspect and measure each punch after cleaning and before transferring the tooling into storage. In most cases, punches that are out of spec with respect to work- ing length can be lightly machined and put back into ser- vice. If the working length of your tooling is out of spec, contact your tooling supplier to discuss repair options. Proper lubrication, cleaning, polishing, handling, and storage can help maintain the integrity of your tablet compression tooling and ensure consistent and efficient tablet production while prolonging tool life and reduc- ing downtime. By implementing a proactive tooling maintenance program, you're not only protecting your company's investment and reducing variable costs, you're helping to maintain or increase production output and improve tablet quality. T&C Cory Terry is manager of parts and accessories at Natoli Engineering (636 926 8900, www.natoli.com). begin to appear, but in many cases, proper polishing will allow a company to place previously unusable tools back into service. The best method for polishing punches is to use a large, unsewn cotton buff wheel. Unlike automated pol- ishing, the cotton-wheel method also refurbishes the punch, which can often double the tool's usable life. Manual polishing refurbishes the punch cup, restores land (the thin flat area around the perimeter of the punch cup), and repairs minor damage to the punch head, back angle, and barrel. However, only a well- trained and experienced tooling technician should per- form this procedure, because an inexperienced techni- cian could destroy a set of tools by over polishing the punches. Great care should be taken to ensure that only a small amount of material is removed during polishing. Handling and storage. A surprising number of tools need to be replaced each year due to punch-tip damage caused by mishandling. Nicks and dings on and around the punch tip are commonly known to cause black specs and product discoloration in tablets as well as capping, lamination, and other visual defects. The costs of such mishandling "accidents" by tablet compression techni- cians add up, but you can minimize them by implement- ing a systematic tooling handling and storage procedure. Proper handling and storage can be as simple as using tooling storage bins available from your tooling supplier. These bins separate individual tools and keep them from striking one another during transport and storage. Other handling solutions include racks and cabinets that pro- tect the tools during transport and storage. It's also a good idea to use a desiccant pack inside the sealed tool- ing storage box or drawer to minimize surface damage from moisture. Photo 2: Using an unsewn cotton wheel to manually polish tools often doubles their usable life.