15 Common Defects & Solutions in IML Injection Labeling_Technical Support

15 Common Defects & Solutions in IML Injection Labeling

Author:SWITEK

Release Date:2026.08.26

Summary of Common Defects and Solutions in IML Injection Labeling Processing (15 Types of Issues)

With the widespread application of in-mold labeling technology in industries such as motor oil, chemicals, daily necessities, food, and pharmaceuticals, domestic in-mold labeling processing is showing a rapid development trend. Since all links in the IML process are closely interconnected, any minor misalignment can cause a sharp increase in defect rates. SWITEK has systematically organized 15 common problem causes and countermeasures in injection labeling processing:

01. Incomplete Single-Point Injection

Possible Causes: 1. Mold eccentricity; 2. Label material issues; 3. Foreign matter on mold surface.

Solution: Detect and adjust mold eccentricity, clean foreign matter from the mold cavity, and evaluate replacing the label material.

02. Label Crossing

Possible Causes: 1. Label horizontal dimension too long; 2. Seams collide when the fixture adsorbs the label simultaneously.

Solution: 1. Modify the label horizontal dimension; 2. Add mechanical positioning to separate adsorption when the label forms on the electrostatic fixture; 3. Modify the label seam position.

03. Label Punch-Through

Possible Causes: 1. Label dimension does not match the mold; 2. Fixture does not match the actual mold; 3. Fixture and cavity not aligned, causing the label to be pulled out; 4. Label not in position.

Solution: 1. Modify the label according to the actual unfolded dimension of the mold cavity; 2. Modify the fixture dimension; 3. Adjust the IML, mold, and injection molding machine level/perpendicularity and verify the fixture position; 4. Re-adjust the label positioning.

04. Partial Label Slippage

Possible Causes: 1. Barrel temperature too high; 2. Poor mold cooling; 3. Mold eccentricity causing uneven melt flow; 4. High mold temperature affecting adhesion; 5. Small mold taper with insufficient tension; 6. Melt index too high; 7. Uneven static electricity distribution.

Solution: 1. Lower the barrel and mold temperature; 2. Increase mold cooling water; 3. Correct mold eccentricity; 4. Replace the label material or product plastic grade; 5. Modify the PE mold static electricity distribution.

05. Label Shift

Possible Causes: 1. Label dimension does not match the mold; 2. PE mold does not match the mold; 3. Fixture and cavity not aligned; 4. Static electricity too low.

Solution: 1. Correct the label and PE mold dimensions; 2. Calibrate the IML system, mold, and injection molding machine level and perpendicularity; 3. Increase the static generator intensity.

06. Seam Label Punch-Through

Possible Causes: 1. Label seam causing label deformation; 2. Label crossing with weak static electricity; 3. Too much label entering the mold bottom, excessive static electricity causing wrinkling.

Solution: 1. Replace the label; 2. Change the label seam position and strengthen static electricity; 3. Re-finely adjust the label placement position in the mold.

07. Product Bottom Label Not in Position (White Leakage)

Possible Causes: 1. Label longitudinal dimension too short; 2. Product and label finish mismatch; 3. Mold structure issues; 4. Static electricity failure; 5. Label too soft/low density.

Solution: 1. Increase the longitudinal height; 2. Match the surface texture (orange peel label with leather grain mold, glossy label with smooth mold); 3. Add a label pressing structure; 4. Repair static electricity; 5. Increase label density/thickness.

08. Partial White Leakage on Irregular Product Bottom

Possible Causes: 1. Label horizontal dimension too long; 2. Mold eccentricity causing uneven wall thickness; 3. Label not reaching the bottom or label material too soft.

Solution: 1. Confirm the seam position and fine-tune the label dimension; 2. Detect product wall thickness and adjust mold eccentricity; 3. Replace label material with better stiffness.

09. Label Seam Serrated

Possible Causes: 1. Label longitudinal dimension too long; 2. Mold eccentricity; 3. Fixture not aligned causing pull-out; 4. Runner too low; 5. Large mold temperature difference.

Solution: 1. Modify the label and fixture dimensions; 2. Re-verify level and alignment; 3. Adjust the water circuit to "one-in one-out" independent circulation to avoid temperature difference caused by series connection.

10. Flat Label Facing Injection Gate: Label Hole/Punch-Through

Possible Causes: 1. Material temperature too high; 2. Hole dimension mismatch; 3. Injection speed too high; 4. Poor label fit; 5. Gate lacks buffer wave points.

Solution: 1. Lower material temperature and injection speed; 2. Adjust the hole dimension; 3. Optimize the PE mold structure for a tighter fit; 4. Add buffer wave points at the mold gate.

11. Injection Point Burn, Pattern Distortion

Possible Causes: 1. Single-layer label inner printing directly scoured; 2. Material temperature/hot runner temperature too high; 3. Injection speed too fast; 4. Gate has no wave points.

Solution: 1. Adjust the label printing side/use composite film; 2. Lower material temperature and hot runner temperature; 3. Use staged injection (significantly reduce first-stage injection speed); 4. Add wave points at the mold gate.

12. Three/Five-Side Labeling Punch-Through

Possible Causes: 1. Label dimension inaccurate; 2. Cutting burrs uneven; 3. Label exchange position incorrect; 4. Mold bottom glue runner design defect.

Solution: 1. Precisely adjust the label dimension and label library position; 2. Replace the high-precision die to improve cutting quality; 3. Modify the mold, add a bottom plastic melt guide channel.

13. Five-Side Full Wrap R-Corner Punch-Through

Possible Causes: 1. Label interface has a gap during fixture forming; 2. Label adsorption sequence on the PE mold incorrect; 3. Cutting burrs.

Solution: 1. Adjust the label dimension, ensure interface overlap of 0.5~1mm; 2. Modify the PE mold label adsorption sequence; 3. Improve mold bottom melt guidance.

14. Label Wrinkling at Seam/Incomplete Injection

Possible Causes: 1. Label cutting does not match the actual product seam; 2. Label protrudes too much on the PE mold, squeezed and wrinkled at the mold bottom; 3. Label thermal deformation.

Solution: 1. Modify the label die and adjust the seam position; 2. Re-adjust the label library and PE mold配合 position; 3. Replace the label with higher thermal stability.

15. Flat Label Wrinkling

Possible Causes: 1. More than one mold injection gate causing multiple melt flow对冲; 2. Label stiffness insufficient (too soft); 3. PE mold static electricity distribution uneven.

Solution: 1. Replace the high-stiffness label; 2. Re-arrange and optimize the PE mold electrostatic field distribution; 3. Coordinate multi-gate injection timing.

Summary Recommendation: IML processing troubleshooting follows the "easy first, difficult later" principle—prioritize checking static electricity intensity, material temperature/injection speed, and label flatness, then deeply verify fixture and mold three-axis alignment and water circuit cooling.

SWITEK Contact Information

WhatsApp/WeChat/Phone: +86 18665171961

Website: www.switek.com.cn

Address: No. 5, Tangbian Nanwei Industrial Park, Chashan Town, Dongguan City, Guangdong Province

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