Issue link: https://www.e-digitaleditions.com/i/1163217
Tablets & Capsules September 2019 13 Dents or dings are major contributors to premature punch-tip wear and failure, and improper handling is their most common cause. Tablet tooling is made from hardened steel, but punch tips are very delicate and easy to damage if they impact another punch or fall on an unprotected floor. The area of highest concern is the land around the perimeter of the punch cup, which is the part of the tool that tends to wear out first and that tends to take the most abuse during handling. Good handling is crucial not only to the life of the tool but also to the proper functioning of the tablet press. A damaged tool can damage the press during operation, which can then impact the next set of tooling, causing a quickly increasing cycle of damage. Tool handling. Companies often blame tool damage during handling on clumsiness or inattention, but proper tool handling procedures can go a long way toward pre- venting damage from occurring. Minimizing handling steps will protect your tools. Examine a tool's life-cycle and write down each step that requires handling: • Decide which tasks you can complete together. For example, do you remove a tool from a tote to per- form a visual inspection, put it back in the tote, and then repeat the process to measure working length? Could you remove a handling step by staging these tasks together? Before choosing an alternative tool steel or coating to protect against flashing from excessive tooling wear, nutraceutical manufacturers should first consider decreas- ing the cup depth and increasing the land width. A shal- lower cup can reduce the amount of compression force required to make a suitable tablet, and a wider land makes for a stronger tool. Excessive compression force. Some machine opera- tors may apply more force than needed to compress a good tablet. This practice increases the pressure in the punch cup, which can lead to increased wear or even fractures to the punch tips. This additional wear increases the clearance between the punch tip and the die, causing more flashing. Using an overload setting that's no more than 20 per- cent higher than the average compression force required to make a suitable tablet is acceptable as long as the coef- ficient of variation (CV) is not wildly high. Typically, a CV value of less than 5 is considered good. The overload settings will alert the operator when compression-force variations are higher than expected, providing the oppor- tunity to correct the variation and reducing the likeli- hood of increased wear. Tablet shape. Shaped punches don't wear evenly around the perimeter of the tip. Since the roller applies torque to the punch head during compression, the punch tip naturally rotates in the direction of turret rotation and becomes snug against opposing corners of the die wall. As a result, flashing is typically uneven on shaped tablets. As previously mentioned, using an interchangeable set- ting tool to pre-torque the punches in the direction of turret rotation when aligning the dies can help reduce uneven flashing. Tooling support. Discuss your options with a tooling company when initially designing a tablet and take advantage of their many years of experience as well as the large cross-section of customer experiences upon which they draw. A tablet design that looks perfect from a mar- keting perspective may not lend itself to ease of produc- tion in a rotary tablet press, and an experienced tooling engineer can help you achieve the tablet design you want while minimizing flashing and maximizing productivity and safety. Tool handling and maintenance Tool maintenance is just as important as other aspects of tableting but is sometimes overlooked, with companies varying greatly in their maintenance practices. Working with your tooling supplier to create good tool-handling and maintenance practices can help reduce flashing. Be sure to include periodic preventive maintenance (PM) schedules in your standard operating procedures (SOPs), optimized for the product or products you're manufactur- ing. To start, review your tool maintenance SOPs with a tooling supplier. Tooling suppliers are the best source for tips to extend tool life. I would also recommend involv- ing your alternate tooling supplier in this process to gain a different perspective. Do you have blank tablets or capsules? We have the printer for you. We have the printer for you. We have the printer for you. We have the printer for you. We have the printer for you. We have the printer for you. We have the printer for you.