What Machines Are Needed To Produce Plastic Bags?

Plastic bag production is a multi-step industrial process that requires a series of specialized devices to work together. Depending on the type of plastic bag (e.g. flat bag, waistcoat bag, roll bags, etc.) and the production process (e.g. blowing film, casting film, etc.), the equipment required varies, but core equipment generally comprises seven categories:
I. Raw Material Processing and Mixing Equipment
* Mixer
:: Self-assembly: polyethylene (PE) granules, mother granules and additives (e.g., antistatic agents, toughening agents) are mixed in proportion to ensure uniformity of raw materials.
* Type: High-speed mixer, vertical mixer, etc.
* Application Scenarios: Production of colored bags, antistatic bags or bags with special properties is required.
* Feed System
:: Function: Automatic delivery of mixed raw materials to the blower hopper, reducing manual intervention.
* Class: Vacuum feeder, spiral conveyor, etc.
ii. Blown Film Forming Equipment (core equipment)
* Blown Film Machine
* ​​Function: molten plastic granules are extruded through a ring die and inflated with high-pressure gas to form thin film tube, which are then cooled and solidified into flat films.
Key Parameters:
Screw Diameter: Determines production capacity (e.g., 50mm screw for small equipment, 120mm screw above for high-speed production lines).
Diameter of die: affects film width (general range 300-3000mm).
Blow-up Ratio: Control film thickness uniformity (usually 2-4 times).
Type:
Single-Layer Blown Film Machine: production of ordinary PE bags, low cost, limited performance.
Multi-Layer Co-Extrusion Blown Film Machine: 2-7 layers of composite film, PE/EVA/PE) can be extruded simultaneously to improve puncture resistance and barrier properties, suitable for food packaging or medical supplies.
Cooling Air Ring
Function: Unified cooling film through circular air duct to prevent thickness deviations caused by temperature inhomogeneity.
Technological Upgrade: Intelligent air rings can adjust airflow in real time and limit film thickness error to ±0.005mm.
III. Film reprocessing equipment
Roller
Function: the cooled film into large rolls (up to 1 m in diameter or larger) for subsequent slitting.
Type: Surface winding machine (suitable for applications with high requirements for high film surface flatness), central winding machine (simple structure, low cost).
Slitting Machine
Function: Cut large rolls of film to a specified width (e.g., 300mm, 400mm) and roll them upside down into small or single rolls.
Key Components: circular knife or pneumatic knife, cutting accuracy up to ±0.5mm.
IV. INTRODUCTION Bag Forming Equipment
Hot Cutting Bag Maker
Function: Reduce film to specified size using heating wire or ultrasonic technology and heat seal the bottom of the bag.
Type:
Flat bag maker: produces simple flat bags up to 300 times perminute.
Vest bag maker: Increases stamping and folding process to produce supermarket shopping bags.
Serial Continuous Roll Bag: Precut and tear lines at the mouth of the bag to produce supermarket food storage bags.
Key Parameters: Heat sealing temperature (adjustable 120-180°C), sealing strength (≥8N/15mm required). Printing press (optional)
Features: Print brand logo, bar code or warning labels on film surface.
Type:
Gravure Printing Machine: high precision (150 lines/inch), suitable for mass production.
Flexographic Printing Machine: Environmentally friendly water-based inks for food packaging.
Digital Printing Machine: does not require plate making, suitable for small batch customization.
Glue Spraying Machine (optional)
Role: Spray hot Sprays hot melt adhesive strips on the opening of the bag for sealing self-sealing bags or express bags.
Precision Requirements: spray volume error should be controlled within ±0.01g/m2 to avoid glue leakage or incomplete sealing.
V. Auxiliary Equipment
Air Compressor
Role: Supplying compressed air to the air shaft and pneumatic components a the blown film machine; pressure is typically ≥ 0.6 MPa.
Freezer truck
Function: Circulate cooling water, reduce die head temperature, prevent plastic from overheating and decomposing.
Waste Recycling systems
Function: Recycling scrap materials, after shredding, cleaning, granulation and reuse, reduce raw material cost. VI. INTRODUCTION Intelligent Upgrade Equipment (Standard Configuration of Modern Production Line)
PLC control system
Function: integrate temperature, tension and speed sensors, monitor and adjust die head clearance and bursting rate in real time.
Visual Inspection System
Function: a CCD camera is used to Detects film thickness, printing color deviation or sealing defect, automatically eliminate defective products.
Robotic Arm
Function: to replace manual labor, complete raw material processing, finished product stacking, etc., and improve production efficiency.
VII. Environmental Protection and Safety Equipment
Exhaust Treatment Device
Function: Purify volatile organic compounds (VOCs) produced in blowing film.
Safety gear
Functions: including emergency stop buttons, protective cover, light curtain, etc., to prevent operators from touching high temperature or rotating parts.
Equipment Selection Recommendations
Small workshop: choose a single-layer blown film machine + flat bag making machine. Investment costs range from $100,000 to $300,000 and are suitable for under 50,000 bags per day.
Medium factory: adopt a multi-layer co-extrusion blown film machine + vest bag machine + machine + gravure printing machine, invest approximately 500,000-2,000,000 RMB, can produce high-end packaging bags.
Large-scale enterprises: the integration of fully automated production lines (from raw materials to finished products, one-click operation) and an MES system, digital management, investment of more than 5,000,000 RMB.
Through rational equipment configuration, plastic bag production can be fully automated from raw materials to finished products, ensuring product quality and environmental performance in line with industry standards, while improving production efficiency.