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Tablets & Capsules September 2020 21 The blue line represents the contact stage. The black line moving from right to left represents the movement of the stylus as it approaches the surface and presses the particle into place. The red line shows the force required to pull the particle away, indicating the inter- active force between the granule and the surface. If the API is the root cause of the sticking, particularly if it is concentrated in one area of the punch tip, the problem can be resolved by selecting a coating with a specific chemistry to overcome the elemental changes. Deformation mechanics. The deformation mechanics, or the physical properties of the granules being com- pressed, can be either plastic (stays deformed) or elastic (springs back to its original shape) in nature. For formula- tions with more elastic, time-dependent deformation behavior, a long dwell time is critical to creating strong bonds between the particles. When a manufacturing situ- ation requires a greater dwell time, using punches with an extended head flat will enable a suitable compression dwell time for an elastic formulation without slowing the press through sticking. Tablet tooling surface. The morphology (surface roughness) of the punch tip face is critical to stop stick- ing. A common misconception among many tooling sup- pliers is that polishing the punch tip faces to a mirror fin- ish will prevent sticking. However, studies of the interaction between different surface textures have estab- lished that the standard specification for tablet punch tip identifying its elements and also removing very small lay- ers of the coating and the steel underneath, this method can examine any interaction between the tool and formu- lation in a localized area of the punch tip. AFM is also used to analyze interface chemistry and spatial heterogeneity to develop anti-stick coatings. This technique can provide nanoscale imaging of sur- faces and has been used to directly assess parti- cle-to-particle and particle-to-surface interactions [1, 2]. Figure 4 illustrates the stages of the AFM experiment. Figure 4 AFM water contact angle experiment Adhesion force (nN) Relative scanner displacement (nm) 10 0 -10 0 500 Adhesion force Contact Us Today! +1 (856) 234 -3626 ackleymachine.com sales@ackleymachine.com Make Your Mark Ask Us About The New VIP Laser Optional NIR & Vision Inspection Innovative Printing & Laser Drilling Machines Flexible, Affordable & Built to Last Output Rates from 50,000 to 1,200,000 / hour FDA & CE Compliant Machines & Accessories for R&D and Production T&C-sept-2020-081320.indd 2 8/14/20 10:10 AM