Here is the sealing technology description of VFFS machine

Sealing technology in VFFS machines is a key component in ensuring packaging tightness, product freshness, and transportation safety. Its design must adapt to different packaging materials (such as plastic film and composite film) and product characteristics (such as preventing liquids from leaking or preventing powders from sticking). Currently, mainstream technologies can be divided into two categories: heat sealing and specialized sealing technologies. Their specific differences and application scenarios are as follows:

Heat sealing technology uses heat to melt the contact surface of the packaging film and apply pressure to bond it. It is the most commonly used sealing method in VFFS packaging machines and can be categorized into three types based on the heating method and structure:

• Principle: A constant temperature heating block directly contacts the packaging film, melting the film at a stable temperature to create a seal. Electrical heating is a common heating method.
• Advantages: Simple structure, low cost, and easy maintenance. Suitable for single films with uniform thickness and good thermal stability (such as PE and PP films).
• Applications: Packaging granular products (such as sugar and cereal) and block products (such as biscuits) without special leak-proofing requirements. Sealing speeds typically range from 30-60 bags/minute.

• Principle: Utilizing a pulsed "heat on, cool off" operation mode, the NiCr alloy heating wire instantly releases heat, combined with pressure applied by silicone pressure strips to prevent the film from burning or deforming due to prolonged high temperatures.
• Advantages: Precisely controllable heat sealing temperature, compatible with multi-layer composite films (such as PET/PE and NY/PE), providing a stronger seal and reducing thermal shrinkage.
• Applications: Packaging products containing oils and fats (such as nuts) or light liquids (such as sauce packets), or for food and cosmetic packaging requiring a smooth seal.

• Principle: Utilizing high-frequency ultrasonic waves (typically 20-40kHz) to generate mechanical vibration and frictional heat on the contacting surfaces of the packaging film, achieving melt bonding without the need for an external heat source.
• Advantages: Concentrated heating and fast sealing speeds (up to 80-120 bags/minute) are achieved without affecting heat-sensitive products (such as chocolate and probiotic powder) due to high temperatures. Furthermore, it prevents seal failure caused by liquids and powders sticking to heating components.
• Applications: High-speed production lines (such as snacks and frozen foods), heat-sensitive products, or packaging liquids (such as sauces) and fine powders (such as protein powder), which are prone to leaking or sticking.

For special needs such as extended shelf life, leak-proof packaging, and easy opening, VFFS packaging machines can be equipped with the following advanced sealing technologies:

• Principle: The bag is vacuumed before heat sealing, and the air is removed before heat sealing. Some models can also simultaneously introduce protective gases such as nitrogen and carbon dioxide (i.e., modified atmosphere packaging).
• Core Value: Significantly reduces oxygen in the bag, delaying product oxidation and deterioration, extending shelf life by 2-5 times, while also preventing powders and granules from clumping due to humidity.
• Applicable Applications: Products requiring high freshness and stability, such as fresh meat, baked goods, nuts, and pharmaceutical powders.

• Structural Design: Utilizes a "double heat seal" (two parallel seal lines) or a "U-shaped seal" (a U-shaped seal line wrapping around the bag edge). Some models are equipped with a silicone seal ring or Teflon-coated heating block to enhance sealing.
• Core Value: Resolves seal cracking issues caused by transport compression for liquids and pastes (such as shampoo and jam), keeping the bag leakage rate below 0.1%.
• Applicable Applications: Products prone to leakage, such as liquid foods, daily necessities, and pharmaceutical ointments.

• Principle: During heat sealing, a special embossing wheel creates a pre-defined tear line (such as a zigzag or dotted break line) at the seal, or uses easy-tear film in conjunction with low-temperature heat sealing, ensuring easy opening without tools.
• Core Value: Enhances the user experience by preventing package damage and spillage due to overtightening, while maintaining overall sealing performance.
• Applicable Scenario: Single-use, small-package products (such as condiment packets, skincare product samples, and medical disinfectant wipes).

When selecting a sealing technology for a VFFS packaging machine, consider three key factors:

• Packaging Material: For single-film materials (such as PE), constant-temperature heat sealing is preferred; for composite films, pulse heat sealing is preferred; for easy-tear films, low-temperature heat sealing or ultrasonic heat sealing is preferred.
• Product Characteristics: For liquids and heat-sensitive products, ultrasonic heat sealing is preferred; for products requiring freshness, vacuum/MAP heat sealing is preferred; for leak-prone products, leak-proof reinforced sealing is preferred.
• Production Requirements: For low-speed, small-batch production, constant-temperature heat sealing is preferred; for high-speed, large-batch production, ultrasonic heat sealing is preferred; for products with high shelf life requirements, vacuum heat sealing is mandatory.