In the plastic film industry, cast film and blown film processes have long occupied a core position. With distinct technical characteristics and performance advantages, they compete fiercely in various packaging and application scenarios. As the two mainstream film production processes, their differences in process principles, product performance and applicable fields are significant, becoming a key consideration for industry selection.

     The cast film process uses a T-die to extrude the melt, which is rapidly cooled and shaped by a chill roll, mainly relying on unidirectional stretching. This unique forming method endows it with prominent advantages: the fast cooling speed inhibits polymer crystallization, resulting in excellent optical properties such as high transparency and low haze, making CPP cast film crystal clear; the thickness tolerance can be controlled within ±1.5%~3%, with exceptional flatness, suitable for high-speed printing and precision coating; the production speed can reach over 500m/min, efficiently meeting the needs of large-scale orders. Its applications focus on fields requiring high appearance and precision, such as inner layers of food packaging, stretch film, hygiene product materials and aluminized substrates.
     The blown film process extrudes the tubular melt through an annular die, inflates it into a bubble with compressed air, cools it by an air ring, and achieves biaxial stretching through longitudinal traction and transverse inflation. Films produced by this process have balanced longitudinal and transverse strength, high toughness and outstanding puncture resistance, so heavy packaging such as supermarket shopping bags and chemical fertilizer bags mostly adopt this process; at the same time, it has low equipment threshold and flexible specification change, can achieve high barrier properties through multi-layer co-extrusion, and is widely used in fields such as agricultural film and heat shrinkable film.
     During selection, comprehensive consideration of product needs is required: cast film is preferred for scenarios pursuing high transparency and adapting to high-speed processing; blown film has more advantages for scenarios emphasizing toughness and durability and requiring flexible production change. Neither process is absolutely superior; the key lies in matching the application scenario and production requirements.

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