Capping Machine Common Problems and Solutions: A Key Guide to Stable Production Line Operation

In modern packaging production lines, capping machines play a crucial role. Whether in the food and beverage, daily chemical, pharmaceutical, or chemical industries, the quality of bottle cap tightening directly affects product sealing, appearance, and consumer experience. However, in practical use, capping machines often encounter various problems, leading to decreased production efficiency, increased product defect rates, and even damage to brand image.

To help companies better utilize capping equipment and reduce downtime due to malfunctions, this article will systematically summarize the nine most common problems with capping machines in production and provide actionable solutions and optimization suggestions.

I. Loose or Untightened Caps

Typical Manifestation:The bottle cap loosens with a slight twist, easily falls off during transportation, and has poor sealing.

Common Causes:Torque setting is too low / Worn capping head rubber sleeve / Deviation in bottle cap and bottle neck dimensions / Insufficient clamping force causing bottle slippage

Solutions: Increase the torque setting, and upgrade to a servo torque control system if necessary / Check if the capping head rubber sleeve is aging and replace it promptly / Check if the bottle cap and bottle neck meet standard dimensions / Increase the clamping force or replace the clamping belt with a non-slip material

Professional Advice:For high-end products (such as cosmetics and pharmaceuticals), it is recommended to use a servo capping system that can precisely control torque to ensure consistency.

II. Over-tightened Caps or Stripped Threads
Typical Manifestation: Bottle caps are deformed, difficult to open, threads are damaged.

Common Causes: Torque setting is too high / Excessive downward pressure from the capping head / Bottle cap material is too soft

Solutions: Reduce the torque setting / Adjust the capping head height to avoid excessive pressure / Replace with a bottle cap material that is more resistant to torque

Professional Advice:
For soft caps (such as PET caps), special attention should be paid to the balance between torque and downward pressure.

III. Crooked Caps (Misaligned Caps)
Typical Manifestation: The bottle cap is not aligned, tilting after being screwed on, affecting appearance and sealing. Common

Causes: Inconsistent cap dispensing direction from the cap sorter / Misalignment of the capping mechanism / Incorrect bottle orientation when entering the capping area / Misalignment between the capping head and the bottle neck

Solutions:Adjust the cap sorter's outlet direction / Calibrate the capping mechanism position / Adjust the conveyor belt guide to ensure bottles enter the capping area upright / Adjust the capping head position to be concentric with the bottle neck

Professional Advice:
Cap misalignment problems are often related to bottle orientation.  It is recommended to add a bottle positioning device before capping.

IV. Bottle Slipping / Unstable Clamping
Typical Manifestation:The bottle rotates with the cap during capping, preventing proper tightening.

Common Causes: Worn clamping belt / Insufficient clamping force / Bottle body material is too smooth

Solutions: Replace the clamping belt / Adjust the clamping distance and pressure / Add anti-slip strips or use a more suitable clamping structure

Professional Advice:
For glass bottles or smooth plastic bottles, it is recommended to use a clamping belt with a high coefficient of friction.

V. Capping Speed Does Not Meet Requirements
Typical Manifestation: Insufficient production capacity, unable to match the filling line cycle.

Common Causes: Insufficient number of capping heads / Cap sorting speed is too slow / Conveyor line speed mismatch / Equipment aging

Solutions: Increase the number of capping heads (e.g., upgrade from single-head to multi-head) / Upgrade the cap sorting system (vibratory feeder → elevator → rotary cap sorter) / Adjust the overall line speed to match / Check if motors, belts, bearings, and other components are aging

Professional Advice: For high-speed production lines, rotary multi-head capping machines should be prioritized.

VI. Bottle Caps Cannot Be Automatically Applied

Typical Manifestation: Bottle caps get stuck, fail to dispense, or fall off, leading to frequent downtime.

Common Causes: Inconsistent cap orientation / Cap sorter blockage / Unsmooth capping track / Unstable cap size

Solutions: Adjust the cap sorter vibration frequency or direction / Clear blockages / Adjust track width and angle / Switch to a more stable cap supplier

Professional Advice:For irregularly shaped caps, it is recommended to use a dedicated cap sorting system.

VII. Unstable Torque

Typical Manifestation: In the same batch of products, some caps are tight, while others are loose. 

Common Causes: Mechanical torque structure wear / Unstable air pressure (pneumatic capping machine) / Servo torque parameters not calibrated / Inconsistent hardness of capping head rubber sleeves

Solutions: Regularly calibrate the torque system / Check if the air source pressure is stable / Adjust the servo torque curve / Replace with rubber sleeves from the same batch

Professional Advice: Torque consistency is the core of capping quality.  It is recommended to establish a regular calibration system.

VIII. Bottle Cap Cracking / Scratching

Typical Manifestation: Indentations and cracks appear on the bottle cap surface, affecting the appearance.

Common Causes: Excessively hard capping head rubber sleeves / Excessive downward pressure / Excessive torque

Solutions: Replace with softer rubber sleeves / Adjust the capping head height /Reduce the torque setting

IX. High Equipment Noise / Significant Vibration

Common Causes: Bearing wear / Unbalanced capping head / Loose machine frame

Solutions: Replace bearings / Calibrate the capping head / Check and tighten machine frame screws 

   Conclusion: Stable capping quality comes from continuous optimizationThe stable operation of a capping machine depends not only on the quality of the equipment itself, but also on correct debugging, maintenance, and control of production details. By promptly identifying problems, accurately determining the causes, and taking effective measures, companies can significantly reduce defect rates, improve production efficiency, and ensure that products maintain a good image in the market.