How Does a Stretching Machine Ensure Uniform Film Thickness?
Time：
2026-07-02 11:16
In the production of biaxially stretched films, stretching machines align molecular chains via longitudinal and transverse stretching, endowing films with outstanding mechanical and optical properties. Film thickness uniformity serves as a core indicator for evaluating product quality, and it directly affects the stability and yield of downstream processing procedures such as printing and lamination. Relying on its self-developed technical center, Nanjing sumino Precision Machinery Co., Ltd. analyzes how stretching machines achieve precise thickness control from two critical dimensions: the temperature control system and the clip chain system.
Uniformity of the temperature system lays the foundational guarantee for stretching quality. During stretching, the film must be heated to an optimal stretching temperature in the preheating section and maintained within a constant temperature field throughout the stretching section. Uneven temperature distribution will create inconsistent elongation rates across different film zones, resulting in thickness deviations or even film rupture. Stretching machines manufactured by Nanjing sumino Precision adopt a zoned independent temperature control system, paired with high-precision temperature sensors and optimized hot air circulation design. This delivers evenly regulated temperature distribution across the full film width, effectively eliminating thickness fluctuations and concentrated internal stress caused by temperature discrepancies, and laying a solid foundation for consistent film thickness.
Precision of the clip chain and track system acts as the key to uniform stretching. In the transverse stretching section, clip chains grip the film edges and travel along dedicated tracks. Stable clamping force of the clip chains and smooth track operation directly determine the uniformity of film deformation during transverse stretching. Nanjing sumino Precision utilizes high-rigidity clip chain structures and precision-machined tracks, combined with servo drives and closed-loop control systems. This ensures excellent synchronization and reliable clamping of clip chains under high-speed operation, mitigating uneven stretching triggered by mechanical vibration.
The setting section represents the final stage for locking film performance. Stretched films undergo thermal setting to eliminate internal stress and fix molecular orientation. Stretching machines from Nanjing sumino Precision are equipped with multi-section independently temperature-controlled setting zones and rapid cooling systems, which accurately regulate crystallinity and residual stress. They keep the film thermal shrinkage rate within target ranges, improving dimensional stability and winding flatness. Through systematic coordination of the temperature control system, clip chain system and setting process, the stretching machine can continuously produce high-quality films featuring uniform thickness and stable performance.
Sumino Heavy Machinery Industry (Nanjing) Co., LTD.
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Adress：No. 116, Suyuan Avenue, Jiangning District, Nanjing
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