Square Bottom Paper Bag Machine: The Intelligent Manufacturing Core of Eco-Friendly Shopping Bags

The square bottom paper bag machine is a dedicated automated device for producing square flat-bottom paper bags. It can complete the entire production process in one go, including paper feeding, forming, gluing, bottom folding, pressing, cutting, and optional handle pasting. Finished bags feature a flat base, stable standing performance and strong load-bearing capacity, making them the core production equipment for eco-friendly packaging in retail, food, gift and other industries.

1. Definition and Core Applications

Also known as flat-bottom paper bag machine, it differs from pointed-bottom bag machines. Its finished products adopt square/rectangular bases with neat and upright bag bodies, large capacity and self-standing capability.

Core application scenarios:

• Retail Shopping: Brand handbags for clothing, shoes & hats, beauty, jewelry and more;

• Food Packaging: Packaging bags for coffee, bakery, takeaway and fast food (e.g., KFC, Starbucks);

• Gift Packaging: Handbags for festival gift boxes, tobacco & alcohol, cultural and creative products;

• Commercial Packaging: Supermarket shopping bags, book & file bags, agricultural product storage bags.

2. Classification by Functional Configuration

1. Standard Non-handle Type: Produces only square bottom bags without handle pasting, featuring low cost and high speed (150-260 pieces per minute);

2. Fully Automatic Integrated Handle Type: Integrates paper rope/flat handle manufacturing and pasting to form handbags in one process, serving as mainstream high-end models;

3. Inline Printing Integrated Type: Equipped with 1-4 color flexographic printing, completing bag making and printing synchronously without secondary processing.

3. Core Structure and Working Principle

3.1 Seven Core Units

1. Feeding Unit: Hydraulic lifting unwinding, constant tension control and automatic deviation correction to ensure stable paper feeding without deviation;

2. Tube Forming Unit: Multiple guide rollers and folding molds fold roll paper into a tubular shape with side gluing and bonding;

3. Cutting Unit: Servo fixed-length cutting with a precision of ±0.5mm;

4. Bottom Folding & Forming Unit: The core module that completes base folding, creasing, gluing and pressing via professional molds to form a standard square flat bottom;

5. Optional Handle Pasting Unit: Automatic feeding, cutting, gluing and pasting of paper rope/flat rope for firm connection with the bag body;

6. Conveying & Counting Unit: Finished product output, automatic counting and stacking, docking with the bag receiving platform;

7. Intelligent Control Unit: Adopts PLC, servo motors and touch screen for parameter setting, fault alarm and automatic lubrication.

3.2 Overall Working Principle

Roll paper → Hydraulic loading → Constant tension conveying → Side gluing → Tube forming → Servo fixed-length cutting → Base folding + gluing + pressing (square bottom forming) → Optional handle pasting → Cooling shaping → Conveying and counting → Finished product stacking.

The whole production line only requires 1-2 operators, greatly reducing labor costs with a waste rate of ≤1%.

4. Core Advantages (vs. Traditional Bag Making)

1. Superior Product Performance: Square bottom bags bear heavy loads (5-10kg), stand steadily with an elegant square shape, effectively upgrading brand image;

2. High Production Efficiency: Fully automatic continuous production delivers efficiency 15-25 times that of manual bag making and over 30% higher than pointed-bottom machines;

3. Wide Material Compatibility: Compatible with kraft paper, white cardboard, coated paper, composite paper and other materials to meet diverse application needs;

4. High Automation Level: Equipped with servo control, automatic deviation correction and fault alarm, easy to operate; new operators can master the machine within 1-2 days;

5. Great Environmental Value: Fully degradable and pollution-free finished bags replace plastic bags, complying with the global plastic restriction trend.

Summary

As a key piece of equipment in the eco-friendly packaging industry, the square bottom paper bag machine stands out with high efficiency, stable operation, premium finished products and energy-saving environmental protection, becoming the preferred bag-making equipment for retail, food, gift and other industries. With the rising global environmental awareness and consumption upgrading, market demand for square bottom paper bag machines keeps growing. The industry is evolving towards high speed, intelligence and multi-functionality, empowering the green transformation and high-quality development of the packaging industry.