Date: 07-12-2021

Plastic Bag Sealing Machine or sealing equipment are devices used to enclose packages having liquids,food in bags, or pouches using flexible films. Some key specifications and essential facts about sealing machines include the sealing method, sealer type, and sealing materials.

 

Working Of Sealing Machines - Sealing Methods

The Sealing machine achieves their core function (creating secure closures) through various methods. Here's a breakdown of some common sealing technologies:

 

1. Heat Sealing: This is the most widely used method. It utilises heat to melt a thermoplastic material (plastics that soften upon heating) on the packaging, forming a strong bond when cooled.

 

• Heat Sealers: Heat Sealing Machine apply heat through bars, wires, or plates to create the seal. They come in various types like:

  • Impulse Heat Sealers: Deliver short heat bursts for quick sealing of thin materials.

  • Continuous Heat Sealers: Apply constant heat for creating long, uninterrupted seals on bags or pouches.

  • Handheld Heat Sealers: Portable and manual for low-volume tasks.

  • Foot Pedal Heat Sealers: Offer hands-free operation for increased efficiency.

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2. Cold Sealing: This method uses pressure-sensitive adhesives pre-applied to the packaging material. When two adhesive surfaces are pressed together, they form a bond without heat.

• Cold Sealers: These machines apply pressure to activate the adhesive bond. They are suitable for materials sensitive to heat or those with pre-applied adhesive coatings.

 

3. Induction Sealing: This method uses electromagnetic fields to heat a metal foil liner placed inside the cap of a container. The heat melts the foil, creating a tamper-evident seal between the cap and the container.

• Induction Sealers: These machines generate the electromagnetic field to heat the foil liner. They are ideal for applications requiring tamper-evident seals, like food and pharmaceuticals.

 

4. Ultrasonic Sealing: This method uses high-frequency ultrasonic vibrations to create frictional heat at the interface of two materials, causing them to melt and fuse together.

• Ultrasonic Sealers: These machines generate the ultrasonic vibrations for creating the seal. They are suitable for materials that don't respond well to heat, like some technical fabrics or certain food packaging materials.

 

 

 

Materials Used For Sealing Machines

The strength of the sealing bond depends highly on the materials used, climate factors, and applied pressure. Different sealing methods require different types of materials.

 

Cold Seal Materials:

There are 6 types of cold seal materials, each having its own peculiar characteristic for different industrial applications.

1. Cohesive Polypaper: A cohesive poly paper is a combination of paper and film packaging materials. This poly paper is considered to be weather-resistan material making it good for products that are vulnerable to climatic change.

2. Cohesive Linerboard: This is an extra heavy-duty paper that provides increased protection to the package. These are customizable with tear strips for easy opening.

3. Returnable Cohesive Package: It has built-in resealable tape for return-ability and perforated packaging for easy peeling.

4. Cohesive Film: Cohesive film is lightweight and flexible in nature. It is mainly used in chocolate bar packaging owing to its water-resistant and puncture-resistant characteristics.

5. Cohesive Single-Face Corrugated: It is considered to be a better option than bubble wrap packaging as it provides better protection to the package. It can be customised with a tear strip for easy opening.

6. Cohesive Paper: It provides protection to products from dust and dirt and is an economical packaging and wrapping material.

 

Heat Sealing Materials:

Since heat sealers are the most used equipment in the food and medical industry, they are used to seal a variety of thermoplastics like PET, HDPE, LDPE, etc. Each plastic is used for different industrial applications.

1. Polystyrene (PS): It is a colourless plastic that lacks flexibility, hence is rigid. It is mostly used to package foods.

2. Low-Density Polyethylene (LDPE): It is thinner and has high heat resilience. Owing to its high toughness and flexibility, LDPE is majorly used in heat sealing applications as a film to protect the package. It is also FDA-approved.

3. Polyvinyl Chloride (PVC): It is the most common type of plastic that is used to maintain the life of the products inside, including medicines. Clear vinyl chloride is used as packaging for medicines, and also as a shrink wrap for a variety of products. It is also used in blister packagings such as for breath mints and chewing gums.

4. Polyethylene Terephthalate (PET/PETE): It is a lightweight plastic that is converted into completely rigid or partially rigid to make it more damage-resistant, and to help increase the shelf life of beverages and solid food inside the container.

5. Silicone: At times, silicone sheets are also used for sealing flexible and rigid packaging. The most common flexible packaging types that use heat sealing include flow wrapping, pouch sealing and, bag sealing, while common rigid packaging applications include cup, tray, and tub sealing.

 

Difference Heat Sealing and Cold Selling

The main difference between heat sealing and cold selling lies in the method used to create the seal and the applicability for different products. Here's a breakdown:

Heat Sealing:

• Method: Uses heat to melt a thermoplastic material (plastics that soften upon heating) on the packaging, forming a strong bond when cooled.

 

• Machines: Heat sealers apply heat through bars, wires, or plates to create the seal. Common types include impulse heat sealers (short heat bursts), continuous heat sealers (long, uninterrupted seals), handheld heat sealers (portable and manual), and foot pedal heat sealers (hands-free operation).

 

• Applications: Suitable for a wide range of products and packaging materials like:

  • Food and beverage packaging (bags, pouches for snacks, coffee, tea)

  • Pharmaceutical packaging (vials, bottles, blister packs for medication)

  • Manufacturing (sealing electronic components, spare parts)

  • Retail (creating custom packaging or resealing merchandise)

 

• Advantages:

  • Creates strong, airtight, and watertight seals.

  • Versatile and suitable for various materials.

  • Cost-effective solution for many applications.

 

• Disadvantages:

  • Not ideal for heat-sensitive products (chocolate, some electronics).

  • Requires compatible packaging materials (thermoplastics).

  • Risk of burning or damaging materials if heat settings are not adjusted correctly.

 

Cold Sealing:

• Method: Utilises pressure-sensitive adhesives pre-applied to the packaging material. When two adhesive surfaces are pressed together, they form a bond without heat.

 

• Machines: Cold sealers apply pressure to activate the adhesive bond. They are ideal for materials sensitive to heat or those with pre-applied adhesive coatings.

 

• Applications: Used for specific products and packaging materials like:

  • Food packaging ( resealable pouches for snacks, cheese)

  • Medical packaging (additionally sealed envelopes for documents)

  • Envelopes and pouches with pre-applied adhesive strips

 

• Advantages:

  • Faster sealing process compared to heat sealing (no heating required).

  • Suitable for heat-sensitive products.

  • Often requires less operator skill compared to heat sealers.

 

• Disadvantages:

  • Bonds may not be as strong or durable as heat seals.

  • Relies on the quality and compatibility of the pre-applied adhesive.