Sealing machines 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 machines generally work on two methods: heat sealing and cold sealing. Hot
sealing is one of the most commonly used sealing methods in the sealing industry.
Cold sealing is a method that involves water-based cohesive coating used to seal a wide range
of film packaging and paper material. Cold sealing is considered to be a complex packaging
method as it involves two films that are laminated together to produce a single inseparable
As the name suggests the cold sealing method lacks heat and is a self-seal adhesive that
requires low pressure to seal the packaging. The films and the cold seal should be highly
compatible to produce a strong seal otherwise this sealing method can be highly unstable.
Cold sealing has many advantages over heat sealing, one of them is speed. Cold sealing is 10
times faster than the heat sealing method and is less damaging than the latter.
Cold sealing can be done either manually or by using machines. Cold sealing machines come in
a variety of models like a mini cold sealing machine and tabletop cold sealing machine to suit
low volume business to high volume business.
Heat sealing is the process of sealing two similar thermoplastic materials using heat and
pressure. Heat sealing machines are mainly of two types- hot sealer bars and impulse sealing
Hot Bar Sealers:
Hot bar sealers are equipment that uses heated bars kept at a constant temperature.
This process is also known as Direct Contact Thermal sealing. This involves heated bars
that directly contact the surface of the material to heat and produce an effective sealing
The bars come with a Teflon guard to avoid the sticking of the thermoplastics to their
Impulse Heat Sealers:
Impulse heat sealers involve a heating element, placed between a tough artificial
rubber. The heat is generated only when electric current flows through the wire of the
sealer as the heating element in impulse sealers is not constantly heated.
The pouch/bag is placed in the heat sealer and is held in between the jaws of the sealer
by applying pressure from the sealing arm. An electric current heats the heating element
for a specified period, which can be adjusted and controlled by the timer provided on the
The heating elements in impulse heat sealers are made up of nichrome which is located
in the top and bottom of the sealing bars.
The major advantage of impulse heat sealers is their safety. High heat is only present
when the sealing jaws are closed under pressure with the pouch in between the jaws.
This means that it is not possible to get burned when contacted with the jaws. While the
jaws can retain a small amount of residual heat over continuous use, the temperature
never reaches a dangerous level hence ensuring the safety of workers.
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-resistant
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
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-
5. Cohesive Single-Face Corrugation: It is considered to be a better option than
bubble wrap packaging as it provides better protection to the package. It can be
customized 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 colorless 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
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
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.
Sealing machines generally find their applications in the food, beverage, and medical sectors.
Each sealing method caters to different types of businesses. For example, cold sealers are
majorly used for snack bars, candy bars, and chocolates, while hot sealers are executed in
preserving fresh vegetables and meat.
From short businesses to large, our team at Smart Packaging Systems can help you with proper
sizing, material selection, and correct sealer that fit your needs at an economical price.