In the actual production of cast films, even with stable equipment operation, common issues affecting product quality are inevitable. The ability of a cast film machine to quickly and accurately identify and resolve these problems directly impacts the effective uptime of the production line and product yield. Nanjing sumino Precision Machinery Co., Ltd. has summarized a systematic set of troubleshooting and solution protocols based on practical experience.

 

Gel Specks: Systematic Inspection from Raw Materials to Temperature

Gel specks are one of the most prevalent defects in cast films. Potential causes include impurities or unmelted materials in raw materials, insufficient plasticization due to low melting temperature, inadequate shear force from improper screw configuration, and low mesh count or damage of filter screens.

For troubleshooting, first check whether raw materials are damp or contaminated. Next, verify that temperatures in each zone fall within the material processing window. Finally, inspect filter screen condition and screw wear. Nanjing sumino Precision Machinery can help optimize screw configuration and temperature profiles according to customers’ actual raw materials and processes.

 

Thickness Variation: Targeted Inspection from Die Head to Cooling Section

Film thickness fluctuation compromises the quality of subsequent processes such as lamination and printing. Factors causing thickness variation are generally concentrated in two areas: the die head and the cooling system.

For the die head: check the uniformity of die lip gap, consistent temperature across all die zones, and residual buildup clogging inside the die.

For cooling: confirm uniform surface temperature of the chill roll, appropriate air knife pressure and angle, and stable chill roll rotating speed.

Cast film machines from Nanjing sumino Precision Machinery are equipped with on-line thickness measurement and automatic die lip adjustment systems to effectively reduce thickness variation.

 

Surface Scratches and Film Rupture: Rapid Diagnosis from Roll Surface to Tension

Film surface scratches are commonly caused by foreign matter or scratches on the chill roll surface, as well as carbon deposits at the air knife outlet.

Film rupture usually results from insufficient melt strength, excessive machine-direction tension, or film embrittlement caused by overly low cooling temperature.

During troubleshooting, prioritize checking the surface finish of the chill roll and cleaning air knife outlets. Then sequentially verify whether melt temperature, winding tension and chill roll temperature are properly set.

 

Routine Maintenance is Fundamental for Problem Prevention

Nanjing sumino Precision Machinery provides customers with detailed maintenance manuals and on-site training to help customers establish a preventive maintenance system, eliminate potential faults at an early stage, and ensure long-term stable operation of cast film machines.