Hot melt adhesive labeling machines play a crucial role in modern packaging production. Due to their high efficiency, stability, environmental friendliness, and cost-effectiveness, they have become the preferred equipment for many manufacturers. This article introduces two types of labeling machines: linear and turret models. We will analyze their working principles, advantages, and disadvantages while providing selection recommendations.
Hot Melt Adhesive Labeling Machine
Labels and Containers
Labels
- Roll-type labels with an inner diameter of 6 inches and a maximum outer diameter of Ø500mm
- Label materials: OPP, BOPP
- Label thickness: 20~60μm
- Label length: 165mm325mm, width: 30mm200mm
- Photoelectric detection blank spacing: 5mm
Containers
- Round bottle diameter: Ø50mm150mm, height: 30mm320mm
- Container materials: plastic (PET, HDPE, PP, PVC), glass, and metal
- Labeling position: 10mm~165mm from the bottle bottom
Applications of Hot Melt Adhesive Labeling
- Mineral Water & Tea Beverages: Labels are applied after filling. The bottle's weight affects labeling accuracy. The adhesive must be low-odor, low-viscosity, operable at low temperatures, and capable of easy reflow, making it ideal for high-speed automated production lines.
- Carbonated Beverages & Soft Drinks: Labels are applied before filling. The bottle weight and expansion due to carbon dioxide filling may affect labeling accuracy.
- Deyu Adhesive for Beverage Bottles: Features low odor, low viscosity, low-temperature operability, and easy reflow, ensuring label stability even after filling.
- Dairy Product Labels: Uses a low-viscosity, cold-resistant adhesive that ensures label integrity even in refrigeration. Suitable for both room-temperature and refrigerated dairy products.
Basic Working Principle of Hot Melt Adhesive Labeling Machines
Hot Melt Adhesive Heating & Supply
Heating Process
Hot melt adhesive blocks are placed in a heating tank, where a uniform heating system melts them to a temperature range of 120°C to 160°C. Different brands require precise temperature control to ensure optimal adhesive fluidity and bonding performance. Insufficient temperature results in poor adhesion, while excessive temperature may cause carbonization or overly fast flow.
Adhesive Supply System
Once melted, the adhesive is transported through a pump or cylinder to adhesive supply pipes and then delivered to the glue application plate. The system maintains a constant temperature and stable adhesive flow, controlled through speed, pressure, and temperature regulators to ensure uniform and consistent supply.
Label Feeding
Automatic label feeders extract labels from the roll while tension control and horizontal alignment devices ensure precise and undistorted label entry into the cutting area.
Cutting Technology
Labels enter the cutting zone, where rotating blades precisely cut them to the required length. Color sensors detect mark points on the labels to ensure size accuracy.
Vacuum Drum Transfer System
After cutting, individual labels are held by a vacuum drum to maintain stable positioning during rotation. Before entering the adhesive zone, the labels are fixed onto the vacuum drum, where the front and rear edges receive approximately 10mm of adhesive to ensure firm attachment.
Hot Melt Adhesive Application System
Adhesive Application Plate
Hot melt adhesive is transferred to the application plate, which features grooves or distribution holes to ensure even adhesive spread onto the drum for subsequent application.
Adhesive Scraper
A scraper removes excess adhesive from the drum, precisely controlling the adhesive thickness to prevent overflow or uneven application.
Uniform Adhesive Coating & Thickness Control
After cutting, labels enter the adhesive application zone, where adhesive is evenly applied to the label's back or designated areas. This ensures strong adhesion without excessive glue affecting the final appearance.
Comparison: Linear vs. Turret Hot Melt Adhesive Labeling
Linear Hot Melt Adhesive Labeling Machine
Working Principle
- Linear Bottle Conveyor: Bottles move along the production line in a straight path.
- Labeling Process: Labels are automatically cut, coated with adhesive, and applied using friction and pressure mechanisms.
- Advantages
Compact Design: Saves factory space.
- Simplified Mechanism: Fewer components require changes when switching bottle types, with a simple gear, belt, or chain-driven system.
- Lower Investment Cost: More affordable initial equipment cost.
- Disadvantages
- Maintenance & Changeover Challenges: The compact structure limits maintenance space, and bottle type changes require lengthy adjustments.
- Higher Wear & Tear: Increased friction in label application, vacuum drums, and bottle guides accelerates wear.
- Limited Application Scope: Mainly suitable for round bottles; rectangular or multi-sided bottles pose alignment challenges.
- Lower Labeling Accuracy: Labels are applied while bottles move along a conveyor, making it harder to maintain consistent positioning.
- Production Speed Limitations: Faster speeds compromise stability and accuracy.
Turret Hot Melt Adhesive Labeling Machine Working Principle
- Screw Conveyor System:
Bottles are separated and guided into the star wheel through the screw conveyor. - Star Wheel System:
- Infeed Star Wheel: Bottles are delivered one by one to the turret mechanism. The infeed star wheel positions the bottles accurately for the next steps.
- Outfeed Star Wheel: Bottles with applied labels are transferred to the outfeed star wheel, which moves the labeled bottles to the conveyor for further processing or packaging.
- Turret System:
- Rotational Movement: The main turret (the larger circular wheel) rotates to transport bottles through various labeling stations, ensuring each bottle passes through the correct processes.
- Individual Bottle Rotation: Each bottle spins on its axis via a smaller rotating wheel (the smaller circle inside the turret), ensuring that the bottle rotates while the label is being applied, resulting in precise and consistent label placement.
Advantages
- Versatile: Handles a variety of container shapes (round, square, multi-sided).
- High Labeling Accuracy: Bottles are stabilized by top pressure, preventing vertical shifts and label misalignment.
- Fast Production Speeds: The combined turret and bottle rotation system ensures smooth, high-speed operation.
- Stable Labeling Performance: Optional air-pressure adjustments simulate post-filling bottle conditions, maintaining consistent label adhesion.
Disadvantages
- Larger Footprint: Requires more factory space.
- Complex Structure: Involves multi-axis movement and precise controls, requiring skilled maintenance.
- Higher Initial Investment: Advanced control systems and precision engineering increase costs.
- High-Speed Synchronization Requirements: Additional synchronization systems are needed to maintain labeling quality at ultra-high speeds.
Conclusion
After comparing linear and turret hot melt adhesive labeling machines, it is clear that both have distinct advantages and disadvantages in terms of working principles, structural design, labeling precision, and production speeds:
Linear Labeling Machines
- Pros: Simpler structure, smaller footprint, lower investment cost.
- Cons: Challenging maintenance and changeovers, limited application scope (mainly suitable for round bottles), lower labeling precision, and speed limitations. Particularly, bottle friction and positioning can cause label adhesion instability.
Turret Labeling Machines
- Pros: Greater adaptability (suitable for various bottle shapes, including round, square, and multi-angled containers), higher labeling accuracy, faster production speeds, and more stable labeling. (Can also be equipped with an inflation system to simulate the pressure of filled bottles, ensuring consistent labeling results.)
- Cons: Larger size, more complex design, and higher initial investment cost.
After a comprehensive comparison, while linear labeling machines offer advantages in terms of cost and space, turret labeling machines are better suited for meeting high-end, diverse packaging requirements in terms of labeling precision, application range, and production efficiency. Given the market demand for high-quality product appearance and production speed, our company specializes in turret labeling technology. Its superior stability and precision can significantly enhance overall production efficiency and product presentation. Therefore, we highly recommend turret hot melt adhesive labeling machines as the preferred choice.
For further inquiries about hot melt adhesive labeling machines, please contact our expert team. We are dedicated to providing the best solutions for you!
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