Understanding the Difference Between Impulse Heat & Constant Heat Sealers

As the flexible packaging sector grows, additional heat sealers are being developed to meet customer demand.

Constant Heat Sealers

Here at Valdamark, we are proud to deliver some of the leading sealing solutions in the UK.

While there are many options for extremely specialised sealers, only three methods of heat sealing are prevalent: impulse sealing, direct heat sealing, and constant heat sealing.

Understanding the benefits and drawbacks of each technique might help the buyer make an informed choice for their application. If you’re not certain what kind of heat sealer you require, whether it’s impulse or constant / continuous, don’t hesitate to get in touch with Valdamark Direct today.

What Is An Impulse Sealer?
Heat sealing on the impulse method is frequently used to weld thermoplastic materials such as Polyethylene and Polyurethane that need a temperature of about 170°F (76.7°C) to form an effective seal.

This versatile method may also be used for sealing a range of other brands and materials, including Mylar, Tyvek® and a wide variety of other bag, pouch and tubing types.

Impulse sealing is frequently utilised to close multi-layer, metalised, and oxygen barrier bags and pouches. An impulse heat sealer may properly join two sheets of thermoplastic materials, if properly configured.

How Do Impulse Sealers Work?
Impulse heat sealers typically have two (round or flat) replaceable heating elements made of a specialised material – often a form of Nichrome alloy – located in the top and/or bottom of the sealing bars. The Nichrome element is sandwiched between a resilient, heat resistant rubber pad and a protective Teflon fabric.

After the materials to be sealed are positioned in the sealer jaws, the operator closes them, and keeps them in-place with the help of pneumatic or mechanical force (depending on the sealer). To create the required sealing temperature, an electric current is then used to heat the element for as long as required.

After the heat cycle is completed, the jaws continue to keep the workpiece in place so that the welded material may cool and fully fuse. Heat sealing generally requires a unique combination of heat, pressure, and time between each step, depending on the substance being used.

What Are The Advantages of Impulse Sealing?
There are many advantages when it comes to impulse sealing, particularly for individual products or smaller packaging runs. Some of the main advantages that businesses across the world choose to take advantage of include:

  • Heat sealing process is extremely quick
  • No preheating required
  • Sealing elements are simple to replace
  • A wide range of materials can be sealed including thick bags
  • Very little energy is used during the sealing process

What Are The Disadvantages of Impulse Sealing?
There are some disadvantages that should be considered when impulse sealing is being used, which include:

  • Requires frequent operator attention
  • Cannot be used for large runs or production lines
  • Can sometimes be more expensive than other types of sealers


What Is A Constant Heat Sealer?
Constant heat sealers, also known as continuous heat sealers, are ideal for high-volume sealing of thermoplastic materials. This type of sealer is frequently used in industrial and production line settings where products need to be sealed rapidly and efficiently.

How Do Constant Heat Sealers (Continuous Heat Sealers) Work?
While the main theory of heat sealing remains the same, a constant heat sealer uses a band of heating elements that are in constant contact with the materials being sealed. As the name suggests, this method involves sealing products by continuously passing them underneath a set of heated jaws.

This means that a constant or continuous heat sealer can package a significantly larger number of products in a shorter period of time than an impulse sealer.

Constant heat sealers, like impulse sealers, use two heated sealing bars – but in contrast to the impulse technique, the sealing bars are continuously maintained at a specific sealing temperature.

Constant heat sealers can keep an accurate degree of temperature control in sealing bars once they have reached operating temperature.

Most contemporary continuous heat sealing machines include safety barriers to prevent burn injuries, even when the seal bars are hot. This makes them ideal for a range of environments, including busy warehouses and factories.

What Are The Advantages of Constant Heat Sealers?
There are many advantages to using a constant heat sealer, which is why they are so popular in production line settings.

Some of these advantages include:

  • Ideal for high-volume sealing
  • Very little operator attention required
  • Rapid and efficient packaging
  • Can be used for large runs or production lines
  • Consistent seals every time

What Are The Disadvantages of Continuous Heat Sealers?
Although there are many advantages to using a constant heat sealer, there are also some disadvantages that should be considered.

These disadvantages include:

  • More expensive than impulse sealers
  • Can be more difficult to set up and operate
  • Not as versatile – can only be used with certain types of thermoplastic materials
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