Plastic Bag Production Process: From Raw Material to Final Product


Plastic Bag Production 101: From Raw Material to Finished Product

For manufacturers and buyers in the plastic packaging industry, understanding the end-to-end production process of plastic bags is essential for selecting the right machinery, optimizing output, and ensuring product quality.

This article outlines the five core stages of plastic bag production, with a focus on the equipment and technical considerations at each step.
Plastic Bag Production Process

1. Raw Material Selection

The primary materials used are polyethylene resins:

  • HDPE (High-Density Polyethylene) – Used for lightweight, high-strength bags like T-shirt bags.
  • LDPE (Low-Density Polyethylene) – More elastic and glossy, suitable for thicker bags, such as shopping and garbage bags.
  • LLDPE (Linear Low-Density Polyethylene) – Offers better puncture resistance and flexibility.

Producers often blend different resins and add color masterbatch, UV stabilizers, or antiblock additives depending on product specifications.

2. Film Blowing Process

The blown film extrusion line transforms raw pellets into continuous plastic film rolls:

  • Process: Resin is melted in an extruder, formed into a tube, then inflated vertically using compressed air.
  • Key Equipment:
    • Blown Film Machine with air ring and IBC (internal bubble cooling)
    • Rotary die head for uniform thickness
    • Auto winder for continuous roll production

Precision in cooling, film thickness control, and tension adjustment directly affects the stability and quality of the finished bags.

3. Bag Converting

The film rolls are then processed by plastic bag making machines which cut, seal, and finish them into different bag types.

Depending on the bag style, the following machines may be used:

  • Bottom seal bag making machine – for flat bags and garbage bags
  • T-shirt bag making machine – high-speed punching and sealing
  • Side seal bag machine – for courier bags and soft loop handle bags
  • Zipper bag making machine, bag-on-roll machine, etc.

Key performance indicators (KPIs) to consider when selecting machines:

  • Output speed (bags/min)
  • Material compatibility
  • Servo-driven control accuracy
  • Automation level (auto stacking, counting, punching)

Plastic Bag Making Machine Comparison Table

Different plastic bag making machines offer different speeds, levels of automation, and applications. Here's a quick comparison to help you choose the best fit for your production goals:

Machine Type Suitable Bag Types Output Speed (pcs/min) Automation Level Ideal For
T-shirt Bag Making Machine Grocery, T-shirt, handle bags 100–300 High Supermarket bag production
Bottom Seal Bag Machine Garbage, flat bags 80–200 Medium General packaging applications
Side Seal Bag Machine Courier, mailing bags 60–150 Medium E-commerce and logistics packaging
Zipper Bag Machine Zipper-lock, slider bags 40–80 Low–Medium Food, apparel, or medical packaging
Bag on Roll Machine Perforated roll bags 150–400 High Food-grade, supermarket use

4. Optional Inline or Offline Printing

If brand or product information needs to be printed, plastic bags are either printed inline during film blowing or offline using:

  • Flexographic Printing Machine – Ideal for high-speed production, water-based inks, and consistent quality.
  • Gravure Printing Machine – Used for high-resolution and multicolor designs.

Critical parameters:

  • Register accuracy
  • Drying efficiency
  • Ink adhesion

5. Inspection, Packaging, and Output

Before delivery, the bags undergo:

  • Heat-seal strength testing
  • Dimensional checks
  • Visual inspection for printing or cutting defects

Automatic counters and stackers are used to bundle bags in set quantities. Bags are packed manually or with semi-automatic systems, then palletized for shipment.

Conclusion

Efficient plastic bag production requires precise control over every stage — from material formulation to machine configuration. The right combination of blown film lines and bag converting machines directly impacts product quality, production speed, and cost control.

If you’re planning to upgrade or set up a production line, understanding which machines best suit your output needs is critical.

Learn more here: What Are the Types of Plastic Bag Making Machines?

For equipment selection, customization, or production consulting, contact Newtop Machine — we provide tailored solutions for your production goals.