If you run a paper cup, paper bowl or paper container production line, side seam leakage is one of the most annoying quality defects. Even if your paper cup forming machine runs normally, you may still get customer complaints: finished paper cups seep water or leak at the vertical seam after filling hot drinks, cold beverages or oily food. So why do some paper cups leak at the seam?
The core reason for side seam leakage is the exposed paper fiber at the overlapping bonding edge. Standard die-cut paper blanks have a raw paper edge without PE coating. When you fold and heat-seal the blank into a cup body, the overlapping seam leaves bare paper fiber open to liquid. Liquid will wick along the porous paper fibers, causing water seepage, leakage or oil penetration. Adjusting sealing temperature, increasing pressure or changing glue formulas can only ease the problem, but cannot completely solve the exposed paper edge issue. Uneven coating, paper blank offset, unstable sealing temperature and worn sealing wheels will further raise the leak rate.
Many paper cup manufacturers keep optimizing the cup forming machine parameters, yet reject rates stay high. The real breakthrough is pre-processing the paper blank edge before cup forming.
This is exactly where the paper blank skiving machine from Shunda Machinery (诚达机械) helps you fix seam leakage at the source.
Shunda Machinery paper blank skiving machine processes paper blanks through a complete set of precision milling, folding and pressing procedures. The machine mills the blank edge thinly, folds the PE-coated layer over the paper edge, and compresses it firmly. After skiving treatment, the whole bonding seam is fully covered with intact PE film, with no bare paper fibers exposed.
With this skiving process, your paper container side wall will no longer leak from the seam. Besides stopping water leakage, the skived edge also blocks oil penetration effectively, which is ideal for paper bowls, soup cups and snack containers holding oily food. Meanwhile, the seamless PE-covered joint greatly improves air tightness of paper cups and paper bowls, helping finished products perform better for hot liquid, cold drink and takeaway packaging.
Using the Shunda paper blank skiving machine brings clear advantages for paper packaging manufacturers:
- Eliminate side seam leakage fundamentally, instead of relying only on sealing adjustment
- Prevent oil seepage for soup, noodle and oily food paper containers
- Upgrade air tightness of finished paper cups and paper bowls
- Reduce defective rate and customer returns
- Compatible with PE coated paper, PLA biodegradable coated paper for eco-friendly paper packaging
- Easy to match with existing automatic paper cup forming lines
Many paper cup factories have already upgraded their workflow: paper blank skiving first, then cup forming. Compared with traditional direct sealing of raw-cut blanks, skived blanks deliver far more stable sealing results, especially for high-speed production lines.
If you are troubled by paper cup seam leakage, oil seepage and unstable air tightness, the Shunda Machinery paper blank skiving machine is a proven upstream solution to improve your paper container quality.
