Application of high frequency heat sealing machine in hot sealing of liquid bag pipe

I. Application Background and Requirements

The connection between liquid bags (e.g., infusion bags, blood bags, nutrient solution bags) and catheters is a critical step in medical packaging, requiring compliance with the following criteria:

• Sealing Integrity: Prevent liquid leakage or external contamination.
• Pressure Resistance: Withstand pressures during transportation and storage.
• Biocompatibility: Materials must be non-toxic, non-irritating, and meet medical-grade standards.
• Production Efficiency: Adapt to large-scale industrial manufacturing.

Traditional heat sealing methods (e.g., hot plate welding, ultrasonic welding) face challenges such as low efficiency, poor sealing, or limited material compatibility. In contrast, high-frequency (HF) heat sealing machines, leveraging high-frequency electromagnetic field heating, have emerged as an ideal solution for liquid bag-catheter sealing.

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II. Working Principle of High-Frequency Heat Sealing Machines

1. High-Frequency Electromagnetic Field Heating
   A high-frequency oscillator (typically 27.12 MHz) generates an electromagnetic field, causing intense molecular friction in the plastic at the connection interface, resulting in rapid localized melting.
2. Pressure Assistance
   Controlled pressure is applied during heating to ensure tight material contact and uniform weld formation.
3. Cooling and Solidification
   Rapid cooling post-welding stabilizes the weld structure.

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III. Technical Advantages of HF Heat Sealing for Liquid Bag-Catheter Connections

Advantage	Description
High Efficiency & Energy Savings	Heating time: 1–2 seconds; energy consumption reduced by over 50% vs. traditional methods.
Superior Weld Quality	Weld strength ≈ material base strength; smooth surfaces with no burrs; excellent sealing.
Broad Material Compatibility	Suitable for PVC, TPU, PE, and other medical-grade plastics.
Sterility Assurance	No adhesives/solvents required; avoids secondary contamination.
High Automation	Integrates seamlessly into automated production lines for continuous output.

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IV. Key Process Parameters for Liquid Bag-Catheter Sealing

Parameter	Role	Typical Value	Adjustment Guidelines
Frequency	Controls heating depth/efficiency	27.12 MHz	Fixed; no adjustment needed.
Power	Regulates weld temperature	5–15 kW	Adjust based on material thickness/speed.
Pressure	Ensures material contact	0.2–0.8 MPa	Insufficient pressure may cause delamination.
Welding Time	Controls melt depth/strength	1–3 seconds	Excess time risks material degradation.
Mold Design	Determines weld geometry	Customized	Precision-matched to bag/catheter dimensions.

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V. Application Cases

1. Infusion Bag-Catheter Connection

• Materials: PVC liquid bag + TPU catheter
• Process:
  • HF heat sealing at 1.5 seconds with 0.5 MPa pressure.
  • Weld strength ≥80% of base material; passes 30-second pressure leak test.
• Advantages:
  • 30% faster cycle time; reduced labor costs.
  • Smooth weld minimizes catheter damage.

2. Blood Bag-Blood Collection Tube Connection

• Materials: Multilayer film (PET/AL/PE) + PVC blood tube
• Process:
  • Two-step HF sealing:
    1. Pre-weld: Low power (5 kW) for 1 second to align components.
    2. Final weld: High power (12 kW) for 2 seconds for robust bonding.
• Advantages:
  • Prevents delamination in multilayer films; maintains barrier properties.
  • Passes biocompatibility tests (no leachables).