School of Engineering and Sustainable Development, De Montfort University, Leicester LE1 9BH, United Kingdom; Department of Engineering, University of Leicester, Leicester LE1 7RH, United Kingdom.
Department of Engineering, University of Leicester, Leicester LE1 7RH, United Kingdom.
Int J Pharm. 2019 May 30;563:135-155. doi: 10.1016/j.ijpharm.2019.01.068. Epub 2019 Feb 10.
In pharmaceutical tablet manufacturing, the powder formulation is filled into a die and compacted into a tablet using rigid punches. Die fill is important because it limits the productivity of tablet presses and determines key quality attributes of tablets including weight and content uniformity. Die fill occurs due to gravity and suction fill mechanisms. A model linear shoe-die filling system has been instrumented with pressure measurement devices for detailed characterisation of air pressure evolution as the powder mass is delivered in the die. Systematic experiments were carried out using a range of microcrystalline cellulose powders to explore the role of powder properties (such as particle size and bulk density) and operating parameters (such as shoe and die geometry, shoe and suction punch kinematics and powder filling level) on powder delivery. Existing models were found inadequate to describe the mass flow rate of powders under a diversity of gravity and suction filling conditions. The pressure measurements enabled the development of a new die fill model using the Buckingham Π theorem. The model includes separate terms for the contribution of the mass of powder delivered under gravity and suction fill mechanisms. The experimental procedures required to extract the parameters of the model are described. The model is applicable to the handling and dosing of fine and cohesive powders where small differences in air pressure have a significant impact on the powder flow process. The practical application of the model for predicting die filling behaviour in a high-speed rotary tablet press is demonstrated by assuming operating conditions of a typical rotary tablet press. This approach can be adapted to assist formulation design and process development for operations involving handling and dosing of fine and cohesive powders.
在制药片剂制造中，粉末制剂被填充到模具中，并使用刚性冲头压缩成片剂。模具填充很重要，因为它限制了压片机的生产率，并决定了片剂的关键质量属性，包括重量和含量均匀性。模具填充是由于重力和抽吸填充机制引起的。已经对模型线性鞋模填充系统进行了仪器化，配备了压力测量设备，以详细描述粉末质量在模具中输送时的空气压力演变。使用一系列微晶纤维素粉末进行了系统实验，以探索粉末性质（如粒径和堆积密度）和操作参数（如鞋和模具几何形状、鞋和抽吸冲头运动学以及粉末填充水平）对粉末输送的作用。发现现有的模型不足以描述在各种重力和抽吸填充条件下粉末的质量流量。压力测量使我们能够使用 Buckingham Π定理开发新的模具填充模型。该模型包括重力和抽吸填充机制下输送的粉末质量的贡献的单独项。描述了提取模型参数所需的实验程序。该模型适用于处理和计量细小和粘性粉末，其中空气压力的微小差异对粉末流动过程有重大影响。通过假设典型旋转压片机的操作条件，演示了该模型在预测高速旋转压片机中的模具填充行为的实际应用。这种方法可以适应于处理和计量细小和粘性粉末的操作，以协助配方设计和工艺开发。
