Heat Sealer 101 Basics and Benefits

Small Business

Packaging is essential – it protects valuable and (sometimes) fragile products during transit. Not only can poor packaging result in the loss of goods but also the loss of profits. Packaging must be fit for purpose, providing a protective barrier between goods and outside elements. Heat-sealed packaging can provide protection and preservation for several items. With proper materials, the heat seal mends two ends together to form an enclosure from exterior products. There are many variations and configurations of heat sealers. In this guide, we explain what heat-sealed packaging is, its many different iterations, types, and specific benefits, and the best practices for using heat-sealed packaging.

What Does a Heat Sealer Do?

Some polymers are thermo-reactive, changing shape and form at high temperatures. Plastics such as polyethylene, polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC) are all thermo-reactive plastics used in bags and other packaging containers that, at the right temperature (roughly 140 degrees Fahrenheit), can have two layers pressed and melded together by a heated machine. This is known as heat sealing.

The type of sealer used depends on the polymer material being sealed, its thickness, and desired production levels. Heat-sealed packaging is quick, efficient, and perfect for high-speed operations. It also provides all-around coverage and complete enclosure of individual or multi-product packs.

As a packaging application, heat sealing has fewer initial investment requirements and is more cost-effective than other forms. The consumer also has a simple time handling and opening heat-sealed packaging. For more information, check out our heat-sealing plastic guide – to find out exactly how the heat-sealing process works.

Do You Need a Heat Sealer for Shrink Wrap?

Heat sealer machines play a vital role in the shrink-wrapping process. At the beginning of fully enclosing any heat shrink-wrapping project, a plastic film is placed around the contents and sealed. For the process to work – and the film to fully wrap around its contents – it must be sealed shut, turning a sheet of film into a bag-like product or enclosing an open bag. The seal seams for shrink wrap are thinner than seals for thick materials.

Some shrink wrap processes such as shrink banding and shrink sleeves do not require a sealer to apply the material. They are not for a full enclosure but for branding or tamper evidence.

What Temperature is Needed to Heat Seal Products?

Thermo-reactive plastics have heat seal temperatures at different levels, so the machine needs to meet the required temperature to seal the wrap being used effectively. The degree of heat needed depends on the material used and its thickness. Plastics such as polyolefin shrink at 280–350 degrees Fahrenheit (121 degrees Celsius), while polyethylene has a heat-sealing temperature of 140 degrees Fahrenheit, or 76.6 degrees Celsius. Polypropylene seals at roughly 248–253 degrees Fahrenheit, or 120–123 degrees Celsius. Temperature cooldown and seal time are also important factors, and thicker bags will require more heat and often have a longer seal and cooldown period.

Can You Use Any Bag with A Heat Sealer?

Technically speaking, plastic is a thermo-reactive material, and any plastic bag can be heat-sealed or melted together. However, it’s essential to consider the different melting points of each plastic type, and the fact that some plastics aren’t mendable and will melt when heat is applied. The melting will not be aesthetically pleasing or practical. So, to ensure the safety of the user, and the integrity of the packaging – and to avoid burning the sealed product – be sure only to use heat seal-approved packaging. A material needs to be mendable and, if it is, it will facilitate the heat-sealing process to occur safely and as expected when heat is applied.

Past a sealable bag, users must make sure the bag will accomplish the task it is used for. Thickness and any other specific properties, such as an oxygen barrier, anti-static properties, or the ability to reclose are always a concern. The material the bag is made from can also make a big difference in the outcome after a heat sealer is used with a bag.

Which Heat Sealer Is Best?

There are many different types of heat sealers – including impulse sealers such as L-bar sealers and I-bar sealers, constant heat sealers, foot switch-operated sealers, and direct sealers – but the qualities that make the most effective heat sealer for a given project are narrowly defined.

Some of the critical considerations when choosing which heat sealer to use include size and portability, energy usage, volume and durability, and price. Different types of heat sealers are suited to a variety of packaging projects and different material types. L-bar and I-bar sealers are commonly used in shrink-wrapping projects, providing a convenient seal around the plastic film before being shrunk down. Plus, a range of portable machines is ideal for smaller or individual projects.

Larger sealers are commonly used for mid-level sealing. For shrink wrap, it’s preferable to have a thin seal and rounded sealing edge. A flatter seal is best for thicker materials, which also provides extra flexibility in the material to stop liquids and heavy products from spilling.

Constant heat sealers are durable and often prove cost-effective for high-volume projects and higher-grade materials. Flat wire seals can be up to a quarter, to two inches thick, while round wire seals average at about one inch thick.

Ultimately, to determine the best heat sealer, you should know the material's type and thickness, along with desired production levels. From there, you can better determine which sealer is best.

What Are the Different Types of Heat Sealers?

There are many different types of heat sealers, and it’s essential to understand the unique functions of each, as well as any benefits and potential drawbacks. Below are the main categories of heat sealers:

Impulse Heat Sealers: One of the most common types of heat sealers. They have one or two heating elements that are covered by a layer of Teflon tape that avoids the risk of the polymer sticking to the heat sealer. The two elements are pressed together over the seal, and a microswitch engages to apply heat. Heat cannot be activated while the bar is open. The seal time usually lasts about two seconds. A key benefit of impulse sealers is safety and cost – while not being used, the heated elements cannot be activated, reducing the likelihood of accidental burns. They are also on the lower end for cost.
Foot Operated Sealer PSB These sealers are usually mounted on desks and activated with a pedal. They can be set to close and open at set intervals. These sealers help output a high volume of seals within a set time, usually on a factory conveyer belt.
Direct Heat Sealer PSF: Also known as constant heat sealers, they can be programmed to pre-heat at different temperatures remotely, which is perfect if a company is working with multiple different types of plastic bags with different melting points. These are also capable of making a more resounding seal, at 10mm, which provides added strength to the sealed package for greater protection during transport.
Continuous Motion Sealers: These heat sealers have continuous sealing ribbons, and bags are sent along a conveyor belt for sealing. Continuous motion sealers are used for high-speed applications and can seal light to a medium-thickness of bags at high speeds.

Which Is the Most Durable Sealer?

A key consideration in determining how durable a sealer is is the sealing blade's quality and type. Impulse sealing blades can quickly wear out if the blade is thin. The more durable sealers are typically hot knife, constant heat sealers. Wider sealing bands for thicker materials can last hundreds of thousands of seals with proper cleaning and maintenance.

What Is the Difference Between Impulse and Constant Heat Sealers?

The main difference between impulse heat sealers and constant heat sealers is in the heating process. While both heat sealers operate using electricity, impulse heat sealers use only a brief pulse to provide heat for a few seconds. Constant heat sealers, however, provide a continued source of heat. While constant heat sealers pose a potentially greater risk to the user through the continuous heat source, they also provide a higher level of overall heat for helping to fuse higher grades of polymer thickness with higher melting points. Impulse sealers are more commonly used to seal at lower production levels and often lighter materials.

Is a Heat Sealer the Same as a Vacuum Sealer?

Heat sealers and vacuum sealer machines are both commonly used to seal plastic bags, but heat sealers only use heat to seal the ends of a bag, while a vacuum sealer removes air from the bag before applying the heat seal. Vacuum sealing is preferred for perishable items such as food, as the absence of oxygen extends a consumable product’s shelf life.

Check out our helpful guide to learn more about the vacuum packing process! Or for more help finding the perfect packing and sealing machine for your packaging projects, chat with our expert team today.

Material Types
PE: Polyethylene
PP: Polypropylene
PPY: Polypyrrole
PVC: Polyvinyl Chloride
POF: Polyolefin
Cello: Cellophane
COEX: Coextruded

Frequently Asked Questions (FAQs)

Q: What Type of Material is a Heat Sealed Bag?
A: Heat Sealed Bags are usually made from some form of poly plastic due to their relatively high tensile strength and ability to be molded with a temperature heat seal. For poly bags with a higher tensile strength, transparency, and electrical insulation, polyethylene terephthalate (PET) is preferred.

Q: Are Heat Sealers Safe?
A: Hand heat sealers and sealer machines are safe when used carefully and with training. Sealer machines heat up quickly when set to high temperatures and should never be handled around exposed skin or left running unoccupied.

Q: What Temperature Is a Heat Sealer?
A: Heat sealing is used for welding together two layers of thermoplastic, usually as a seal in a thermoplastic bag. Thermoplastics are heat reactive and tend to melt and seal at roughly 140 degrees Fahrenheit, which means a heat seal must press together two layers at this temperature to seal them properly.

Q: How Long Does it Take to Heat Seal a Product?
A: It is determined by the thickness and type of material used, but will often take less than two seconds to fully seal.

Q: What is a validatable Sealer?
A: The benefit of a validatable sealer is the ability to verify temperature, speed, and bar pressure during the process. This is required for any packaging needing to meet International Packaging Standards 11607-2.

Q: Does the heat sealer need to be the size of my product?
A: If using a bar sealer, the sealing bar should be larger than the product being wrapped. A complete seal will not be reached if the bar is shorter than the product.

Q: How often do heat sealer parts need to be replaced?
A: When stacking pallets before transit, it’s important to make sure all items are stacked evenly with balanced surface area distribution. Poor stacked pallets are harder to store and more likely to break during transit, leading to higher carrying and replacement costs for damaged products.