As a professional R&D and manufacturer of polymer material processing equipment, POTOP has long been dedicated to the field of cast film extrusion. Our extrusion dies for cast film machines feature sophisticated structural design and reliable performance, widely used in material research, formula testing and pilot production.
Three Types of Extrusion Dies: Structure & Characteristics
●T-die
The T-die adopts a standard manifold with a simple and straightforward structure. It is easy to machine and maintain. Molten material remains in the runner for a relatively longer time, so this die is ideal for general polyolefin resins with good thermal stability. It is commonly used to produce regular films and sheets with moderate thickness tolerance, perfectly suited for basic formula development and simple sample preparation.
●Fish-tail die
Featuring a fan-shaped runner, the fish-tail die has a moderate spreading angle and medium melt distribution capacity. With balanced comprehensive performance, it works well with most medium-viscosity resins. It is widely applied in trial production and small-batch manufacturing of general packaging films and conventional functional films, delivering a good balance between cost and forming quality.
●Coat-hanger Die (Mainstream & Recommended Model)
As the flagship product of Guangzhou Putong, the coat-hanger die consists of three functional sections: manifold section, fan-shaped spreading section and die lip section.
Compared with the T-die, it has a smaller manifold diameter, which greatly reduces melt residence time. This makes it particularly suitable for special resins and ultra-thin sheets that are sensitive to heat and shear duration.
The manifold diameter gradually decreases along the material flow direction and forms a reasonable inclination with the cross-section of the die lip. This design realizes precise melt distribution across the full die width and significantly improves thickness uniformity of films and sheets.
With a larger spreading angle than the fish-tail die, the coat-hanger die delivers higher distribution efficiency. It shortens the overall axial length of the die and reduces pressure drop during melt transportation, thereby boosting production capacity.
From the perspective of rheology, the coat-hanger die maintains constant pressure drop inside. Its forming performance will not be affected by operating parameters, ensuring outstanding operational stability. Currently, it has been widely adopted as the top choice for high-precision cast film production.
Forming Process Features
Melt distribution performance of the extrusion die is the core of cast film processing. Equipped with our professional coat-hanger die, the cast film machine converts cylindrical molten raw materials into flat and uniform sheet flow via optimized runners, manifolds and choker structures.
The processing technology boasts three core advantages:
●Uniform flow across full width: Consistent flow rate, temperature and material properties at the die outlet effectively avoid film thickness deviation.
●High-pressure dense forming: Optimized runner design creates stable internal pressure to eliminate weld lines and enhance the density and mechanical strength of finished products.
●Low deformation & stable operation: Precision flow path design prevents product distortion and warpage, meeting the production requirements for ultra-thin and high-precision functional films.
Process Adaptation & Industry Applications
Supported by our full range of extrusion dies, POTOP cast film machines are compatible with PE, PP, EVA, PA and various functional resins for R&D and testing purposes. Our equipment serves a wide range of industries including polymer materials, packaging, new energy, medical materials and agricultural products.
For high-end applications such as high-barrier films, ultra-thin samples and premium functional films, we standardly equip the production line with coat-hanger dies. Combined with an automatic control system, the whole process from material melting, uniform distribution to cast film forming runs stably and continuously.
