Powder or mother granule in rotated fluid-bed will undertaken the action of air flouting force in ring gap, rotating centrifugal force and gravity itself and appear cycle rope strain shape.

• 粉末或者目力在旋转流化床内，受到环隙空气浮力，旋转离心力、自身中力作用，呈环周绳股状，粘和剂或包衣液喷入料层形成真球度及高的丸粒或连续均匀的衣膜。