Issue link: https://www.e-digitaleditions.com/i/870536
Tablets & Capsules September 2017 23 Is your operation ready for multi-tip tooling? Almost all presses can accommodate multi-tip tooling, but several aspects must be considered before investing to ensure production runs smoothly. The press must be in good working order, with no sig- nificant wear in the turret area, including punch guides, keyways, and die pockets. Replace the cams if they show excessive wear or degradation to prevent damage to the punch heads. The upper turret must have a keyway in the guide to ensure the punch tips align with the dies. The lower tur- ret doesn't require a keyway because the punch tips remain in the dies. Nonetheless, keyways are beneficial there because they speed setup and reduce the likelihood of damage to the lower punch tips. The feeder paddles may need modification to ensure they deliver enough formulation to the dies. This could be as sim- ple as lowering the paddle assembly closer to the die table or it may require using a paddle feeder with angled blades. Not all press instrumentation and monitoring systems can accommodate multi-tip tooling. Assess the system before installing multi-tip tooling to ensure it can provide accurate production information. The tablet ejection sys- tem must be able to handle larger production volumes to avoid blockage in the discharge chute. Adjusting the take- off angle may be necessary so that individual tablets don't interfere with each other during ejection. Test the flowability of the formulation. Multi-tip tabletting may require the dies to fill faster, which requires good flow of the granulation. If the granulation doesn't flow fast enough, problems can occur, including material bridging, feeder overfill, and tablet weight variation. You may need to modify the feeder mechanism to allow the press to maintain its turret speed. This may include modi- fying the feeder paddles, as mentioned above, and/or the feed frame so it can accommodate a larger hopper. Particle size distribution is another important factor. If the formulation has a high percentage of fines, particles may be more likely to enter the clearance between the tip and die wall, build up, and cause tightness and friction in the lower punches, leading to premature head wear and damaged cam tracks. If it's not possible to modify the particle size distribu- tion, consider changing the tablet design and/or the working tolerance between the tip and die wall as a work-around. You should also assess the design of the tablet. Naturally, tablet size is the primary factor that deter- mines how many tips a punch can accommodate, but shape matters, too. Ovals can be challenging to arrange while maintaining a robust punch, optimizing die filling, and improving tablet take-off. If your press includes a wash-in-place system or if con- tamination and space constraints are major concerns, monoblock tooling is likely the best option. Whatever you decide, assess the quality of the tooling and the process used to make them to determine whether they will enable the tooling to withstand the rigors of produc- tion and allow the press to work at the compression rates and speed your operation requires. —S.O.