Plastic Bag Production Process: Step-by-Step Manufacturing Guide (2026)

For investors and manufacturers entering the packaging industry, understanding the end-to-end plastic bag production process is the foundation of success. It is not just about melting plastic; it is about precise temperature control, tension management, and selecting the right machinery for each stage.

This guide outlines the 5 core stages of manufacturing plastic bags, mapping each step to the specific equipment required to optimize your output and quality.

Step 1: Raw Material Mixing

Every great product starts with the right recipe. The primary raw materials are Polyethylene (PE) resins:

• HDPE (High-Density Polyethylene): Used for strong, thin bags like supermarket T-shirt bags.
• LDPE (Low-Density Polyethylene): Used for glossy, flexible bags like luxury shopping bags or trash liners.
• Additives: Calcium Carbonate (filler to reduce cost), Masterbatch (for color), and UV stabilizers.

The Process: These materials are fed into a high-speed mixer to ensure a uniform blend before entering the hopper.

Step 2: Blown Film Extrusion

This is the most critical stage. The mixed pellets are transformed into a continuous roll of plastic film.

• Melting: The extruder screw melts the plastic at high temperatures (approx. 200°C).
• Blowing: The molten plastic is extruded through a circular die and inflated with air to form a "bubble." The size of this bubble determines the bag's width and thickness.
• Cooling & Winding: The film is cooled by an air ring, flattened, and wound into jumbo rolls.

Required Machinery: To ensure uniform thickness and a stable bubble, you need a high-performance Film Blowing Machine. Advanced models feature Rotary Die Heads and ABA Co-Extrusion technology for cost savings.

Step 3: Flexographic Printing (Optional)

If you are producing branded shopping bags, the film roll must be printed before it is cut.

The Process: The film roll is passed through a printing press where ink is transferred onto the surface using flexible relief plates.

Required Machinery: For high-speed production, a Flexographic Printing Machine is the industry standard.

• 2-4 Color Stack Type: Ideal for simple logos on T-shirt bags.
• 6-8 Color CI (Central Impression): Essential for high-precision, photo-quality images.

Step 4: Bag Converting (Cutting & Sealing)

This is where the film roll becomes a finished bag. The roll is fed into a cutting machine that heat-seals the bottom or sides and cuts the film to the desired length.

Selecting the Right Machine:

• For T-Shirt Bags: Use a Heat Sealing Cold Cutting Bag Machine. It punches out the "U" shape handle automatically at high speeds (up to 300 pcs/min).
• For Garbage Bags: Use a Bottom Sealing Bag Machine. These handle thicker films and create a strong seal to prevent leakage.
• For Bread/Clothing Bags: Use a Side Sealing Bag Machine. This creates a neat seal on the sides, often used for BOPP/PP display bags.

Quick Comparison: Which Machine Do You Need?

Step 5: Recycling (The Zero-Waste Loop)

Modern manufacturing must be sustainable. The "waste" produced during cutting (like the handle punch-outs from T-shirt bags) should not be thrown away.

The Process: Scraps are fed into a Plastic Recycling Machine (Granulator), melted down, and turned back into pellets. These recycled pellets can be mixed with virgin material in Step 1 to reduce raw material costs significantly.

Conclusion

Setting up a plastic bag production line requires syncing the right film blowing, printing, and bag making technologies. A mismatch in capacity or compatibility can lead to bottlenecks.

Ready to start? At Newtop Machine, we don't just sell machines; we provide full-line solutions.

• Read our guide on Types of Plastic Bag Making Machines to dive deeper.
• Contact our engineering team today for a customized factory layout proposal.