10 Common Paper Cup Machine Problems and How to Fix Them

10 Common Paper Cup Machine Problems & Fixes | Troubleshooting Guide by Ruida Machinery

As a paper cup manufacturer, machine stability and production efficiency are critical to your success. However, even the most advanced paper cup forming machines can encounter issues over time, especially without regular maintenance.

In this guide, we’ll walk you through 10 common paper cup machine problems, how to diagnose them, and practical solutions for getting your production line back on track.

1. Inconsistent Cup Sealing (Side Curling or Opening)

Problem

Cups fail to seal properly, with curled sides or loose joints.

Causes

• Incorrect temperature setting of the side sealing heater
• Uneven pressure on the sealing wheel
• Low-quality or non-uniform PE-coated paper

Solution

• Check the sealing temperature (typically 250–300°C depending on paper type)
• Adjust the pressure of the knurling wheel
• Use uniform and certified PE-coated paper roll to ensure bonding quality
• Related: PE-Coated Paper Roll for Paper Cup Production

2. Cup Bottom Leakage

Problem

Water leaks from the bottom of the paper cup.

Causes

• Insufficient bonding pressure at the bottom heating section
• Improper bottom paper size or folding tension
• Low temperature in the bottom preheating unit

Solution

• Increase bottom heater temperature gradually (not exceeding safety limits)
• Confirm that the bottom disc size matches the cup diameter
• Clean heating plates regularly for consistent temperature transfer

3. Excessive Waste or Paper Jamming

Problem

Frequent paper jams and high paper waste ratio (above 5–8%).

Causes

• Mismatched cup design and mold size
• Improper fan-shaped paper die-cutting
• Loose paper feeding rollers

Solution

• Verify your paper cup die cutting machine settings and template precision
• Lubricate the rollers and check paper alignment
• Use a sharp, calibrated die-cut mold for uniform fan shapes

Related: Paper Cup Die Cutting Machine

4. Motor Overheating or Tripping

Problem

The main drive motor overheats or shuts down during extended operation.

Causes

• Poor lubrication
• Overloaded production settings
• Faulty motor bearings

Solution

• Lubricate all moving parts as per the machine maintenance schedule
• Reduce speed settings (e.g., from 230 pcs/min to 180 pcs/min) during peak hours
• Replace or inspect motor parts if overheating persists

5. Irregular Cup Height or Shape

Problem

Cups produced have uneven height or inconsistent rim shapes.

Causes

• Cup wall paper feeding misalignment
• Fan-shaped paper size variation
• Faulty forming mold or tension spring

Solution

• Adjust paper cup printing machine alignment to reduce paper skew
• Replace damaged tension springs or forming dies
• Calibrate the cup guide track for symmetrical shaping

Related: Paper Cup Printing Machine

6. Holes or Wrinkles on the Cup Body

Problem

Visible pinholes or paper wrinkles after forming.

Causes

• Overheating during side sealing
• Paper moisture imbalance
• Excessive side pressure

Solution

• Fine-tune heating to recommended range (avoid overheating)
• Store raw materials in a controlled environment (40–60% humidity)
• Reduce mechanical pressure slightly on forming unit

7. Machine Stoppage After Few Minutes

Problem

Machine stops automatically shortly after running.

Causes

• Sensor misalignment
• Emergency switch triggered
• PLC control unit error

Solution

• Check all sensor heads and limit switches for dust or blockage
• Reset the emergency stop and run diagnostics on PLC (if applicable)
• Consult manufacturer for software resets or part replacement

8. Noise and Vibration During Operation

Problem

Unusual noise or shaking during production cycles.

Causes

• Worn-out bearings or belts
• Loose structural bolts
• Imbalanced forming dies

Solution

• Inspect and tighten all major fixtures weekly
• Replace worn belts and apply grease to all gears
• Check cup forming mold concentricity

9. Incomplete Cup Ejection or Blockage

Problem

Cups do not eject properly, causing a jam in the discharge section.

Causes

• Ejection cylinder pressure drop
• Cup stacker misalignment
• Build-up of cup residue or dust

Solution

• Increase pneumatic ejection pressure slightly
• Clean the cup stacking channel regularly
• Adjust the discharging belt or tray position

10. Inconsistent Production Speed

Problem

Speed fluctuates or drops below the set number (e.g., 180 pcs/min instead of 230 pcs/min).

Causes

• Worn gear parts
• Paper feed tension variation
• Voltage fluctuations

Solution

• Replace aging gears or belts
• Stabilize the voltage with an AV regulator
• Run calibration to restore consistent speed

Related: Automatic Paper Cup Forming Machine

Maintenance Tips for Smooth Operation

Need a complete preventive maintenance checklist? Contact us.

Final Thoughts

Regular troubleshooting and proactive maintenance can significantly reduce downtime and improve machine life. Whether you're running a new startup or managing a high-capacity factory, understanding these common issues helps ensure consistent production of high-quality paper cups.

At Zhejiang Ruida Machinery Co., Ltd., we’re committed to supporting every customer with the tools and knowledge they need to run smoothly.

Need Technical Support?

If you're experiencing any of the problems above—or want to upgrade to a more reliable paper cup production line—feel free to contact our support team for guidance, spare parts, or machine upgrade advice.