Paper Bag Machine: The Engine of Sustainable Packaging

The Workflow: From Paper Roll to Finished Bag

The core principle of a paper bag machine is to automate the entire manufacturing process continuously. While designs vary, the general workflow involves several key stages that transform a roll of paper into a finished bag in one seamless operation:

Unwinding and Feeding: A large roll of paper (the base material) is mounted on the machine. The paper is fed into the system under controlled tension to ensure smooth and consistent processing.

Tube Forming and Gluing: The flat sheet of paper is shaped into a tube. This is typically done by folding the paper and applying glue along the edge to create a strong seam—a process known as tube forming and edge gluing (成筒、粘边).

Bottom Forming: This is a critical step where the bottom of the bag is created. For common square-bottom bags, this involves folding, gluing, and pressing the bottom to secure it. More advanced machines can produce various bottom types, such as the robust square bottom often used for shopping bags with handles.

Cutting and Stacking: The continuous tube of paper is cut into individual bags of predetermined lengths. Finally, the finished bags are counted and stacked automatically for packaging and shipment.

The entire process is managed by advanced control systems, often featuring Touchscreen Human-Machine Interfaces (HMI) and Programmable Logic Controllers (PLC) for precise control over speed, dimensions, and glue application.

Key Technical Features and Capabilities

Modern paper bag machines are equipped with features that ensure high productivity, consistency, and quality:

High-Speed Operation: These machines can produce a significant number of bags per minute, with speeds ranging from 40 to 60 bags per minute for many models, making them ideal for large-scale production.

Precision and Consistency: Utilizing technologies like servo control systems and photoelectric tracking, the machines guarantee that each bag is identical in size and print alignment (if using pre-printed paper), which is crucial for brand consistency.

Versatility in Production: A single machine can often be configured to produce different types of bags, including tote bags with handles, flat bags, food bags (like bread bags), and gift bags. They can handle various paper weights, typically from 70 to 230 grams per square meter (gsm).

"Foolproof" Automation: Many machines feature automatic lubrication, tension control, and error-detection systems. If a problem like a paper jam or a misaligned color mark occurs, the machine can automatically stop and alert the operator.

Types of Paper Bag Machines

The term "paper bag machine" encompasses several specialized types designed for different end products:

Single-Sheet Handle Bag Machine: Uses pre-cut single sheets of paper to produce high-quality shopping bags with handles.

Roll-Fed Square Bottom Bag Machine: Feeds from a large paper roll and is highly efficient for producing common shopping bags with a square bottom.

Food Bag Machine: Specifically designed for producing bags used in food service, such as those for bread, pastries, and fast food, often with features for creating specific folds or seals.

Paper-Plastic Composite Bag Machine: Produces heavy-duty bags used for packaging materials like cement, animal feed, or chemicals by combining paper with other layers for strength.