During the IML (in-mold labeling) production process, label film wrinkling is a relatively common quality defect. This is usually caused by the combined action of multiple factors such as poor fit, uneven melt flow, force deformation, cavity air entrapment, and shrinkage rate mismatch.

• Poor Fit: The label film cannot closely and well fit the mold cavity.

• Uneven Flow: Molten plastic flows unsmoothly and unevenly during the filling process.

• Excessive Force: High injection pressure causes the label film to be excessively stretched or squeezed.

• Cavity Air Entrapment: Gas inside the cavity cannot be discharged in time during plastic filling, forming air entrapment.

• Shrinkage Difference: The plastic shrinkage rate of the label film and the product to be labeled differs too much.

• Uniform Wall Thickness: The wall thickness design of in-mold labeled products should be kept as uniform as possible.

• Mold R-Angle: The fillet radius of the moving mold or fixed mold is recommended to be designed above 0.3 mm.

• Anti-Deformation Structure: Optimize the label shape, add anti-wrinkle structures to control film deformation.

• Optimize Filling: Adjust the injection filling sequence and speed to effectively alleviate cavity air entrapment.

• Shrinkage Matching: Control the shrinkage rate of the label film and the product to be labeled within a range as close as possible.