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Heat Sealer

A heat sealer machine (or bag sealer) is a device used to seal various types of packaging and thermoplastic materials. There are different designs for different sealing work requirements.

When choosing a heat sealer, the first and most obvious question to ask is what are you trying to seal?

Heat sealers are used to seal a wide variety of materials to suit many different applications and projects.

Heat seal bags are hermetically sealed ensuring that your products are tamper proof, airtight, waterproof and hygienically enclosed.

Often you will have a pre-cut bag or pouch that will contain identical monolayers. In other words just ‘single layer’ materials. Like simple plastic bags.

Other packaging like foil bags or gusset pouches may have several layers that need to be sealed at once. So, your sealer will need to be suitable for laminated, multi layer materials.


Hand Held Heat Sealers


Hand Held Heat Sealers

Hand Held Heat Sealers are a speciality for Valdamark. These are machines we use in our own hand fabrication and production facilities. We know and trust them as the best available for professional heat sealing.

Our current range are all lightweight, easy to use machines that create optimal seals consistently and with ease. This is essential when doing mid to high volume sealing work as the operator will require a reliable machine that is lightweight to avoid handling fatigue. Most importantly of all though is that the machine is safe to use!

In our experience most of the commercial hand heat sealing machine models on the market are unsuitable for repeat or high volume sealing.

We have machines like the WSZ which is preferred for thick, multi layered, heavy gauge industrial packaging like bulk bags, octabin liners and other export packaging materials. The WSZ machines are available in either 300mm & 400mm jaw widths and can be supplied as standard or with PTFE coated blades.

All our machines are approved to the CE standard as well as being built in accordance with the GS standard for electrical work. Each comes complete with a 2 years manufacturers warranty.


Impulse heat sealer

Bag Sealer

Impulse heat sealer machines deliver heat in an impulse (or short interval).

They use a low voltage heating containing wires that have virtually no heat up time. This allows you to get up to your desired temperature and seal in seconds.

The heating element then cools down but retains the pressure allowing the seal to set.

This makes them economical to run as from a power perspective, the power is only used during the actual sealing process.

Usually these devices are used on packaging that contains identical thermos-plastic films on all seal sides. This is usually a polythene material but not necessarily as they can, and often are used for thinner gauge laminate materials.

Our most popular unit here is the ISZ hand held heat sealer. This professional, portable machine can seal virtually any thermoplastic film safely and efficiently. It’s lightweight and fast operation make it a perfect choice for the sealing of larger or more awkwardly sized products that can be difficult to manoeuvre around.

ISZ Impulse Sealers will suit most projects, being able to easily handle polythene films up to 600 gauge or 150 microns. Typically though we find our sealers can seal single layer films in excess of 300 microns quite easily.

If you require a standing unit then the range of HPL table top machines are our most popular model here. It’s a fixed unit available in a variety of different sizes complete with a cutter function as standard.

There are devices available for heavier gauge or multi layered polythene. As well as this other material constructions like Nylon, Polypropylene, Polyurethane and PVC can be suitable for an impulse sealer. We would advising trialling this tough first. .

All our impulse sealers have built in electronic timers so you can accurately control the sealing cycle.

Some models go further with the addition of a specification timer that indicates the seal cooling period. This feature allows you to maintain the quality and consistency of seals even more accurately.

Click to watch a video of the ISZ  product range



Constant heat sealer

Heat Sealing Machine

A constant heat sealer machine will deliver heat in just that way, constantly! More specifically this concept refers to a manual sealing machine whereby heat is applied for as long as the operator compresses the sealing bars.

In other words you select the appropriate sealing temperature and clamp the seal for as long as is necessary for the material to weld!

This is slightly different to an impulse sealer in that with an impulse machine the only setting is ‘on & off’. You cannot adjust the temperature usually. The seal time is pre-set by the operator. Usually between 1 & 10 seconds.

Constant machines do seem to be slightly better suited for heavy duty bag sealing as you are able to take advantage of the higher temperature settings and also time each seal. This makes ideal for industrial bag sealing. The WSZ is very compatible with bulk bags, container liners, octabin packaging & gusset bags.

It is worth considering though that modern impulse heat sealing machines such as the ISZ will match the performance of constant heat sealers in terms of seal quality and strength.


Click to watch a video of the WSZ product range


To crimp or not to crimp? 

The word crimp refers to the serrated seal pattern on some packaging machines. Its primarily there to improve seal strength and avoid de lamination of any multi layered materials.

This id often referred to as the crisp bag sealer. Or crimp heat sealer.

It’s the clients personal preference to have this or not.

The WSZ machine featured above is our most popular machine for this type of heat sealing.

This hand held heat sealing machine features two serrated jaws and is suitable for cellophane, waxed papers, barrier foils and other metallized or aluminium laminates.


What material will you be sealing ?

Pouch Sealer

Many sealers can seal different types of materials, but it is important remember that some are not suitable for certain materials and different thicknesses.

Our range of heat sealers are market leading and will seal the majority of flexible packaging materials and constructions. The best way to be certain is to send us a sample for testing.

  • Polyethylene including HDPE, LLDPE and PE
  • PVC
  • Polyethylene Terephthalate or PT
  • Aluminium Foils
  • Metalized Polyester
  • Cellulose or Barrier Foils


Foot operated bag sealer machines

Foot Operated Bag Sealer

Our HPL range are all foot operated impulse sealers as standard.

A foot pedal allows the operator to complete the seal cycle ‘hands free’ whilst safely allowing them to concentrate on positioning the packaging correctly. It is a faster process as well.

The HPL is a professional machine that is perfect for use in medical and pharmaceutical packaging environments.

Well suited to the sealing of sterile barrier packaging films it can be supplied as a stand alone machine or with a range of options including a work table and roll holder/ film unwinder.

If you are looking for a standing sealer take a look at the V2A vertical stand and work table options for further improved efficiency.

This food grade, stainless steel construction is a popular configuration where Good Manufacturing Practice (GMP) guidelines need to be adhered to. These products conform in full with the CE European Safety Standards and carry the GS standard for electrical and technical work.

Sealing machines have different widths to suit the width of the seal you want to create. As a rule, choose a sealer that is between 20mm and 50mm wider than the width of your packaging.

This just gives you more manoeuvrability as the packaging can easily be positioned without overlapping the edges of the machine.

Our heat sealing machines start at 300mm width all the way up to 1000mm. These sizes will suit most projects but bespoke widths can be made to order.


Heavy duty bag sealer

Click to watch a video of the HPL product range


Table Top Heat Sealers

These manual operation machines are ideal where film on a roll needs to be cut to size.


Table Top Heat Sealer




Rotary Heat Sealers

Rotary Heat Sealer


Rotary foil bag sealers are usually used for laminated materials made up of multiple layers of thermoplastic film.

These can have different mechanical properties and melting points depending on the construction.

Laminate Foils, coated papers, cellulose films, cellophane and polypropylene films will often require a constant seal.

Our devices all have temperature controllers to keep the seal bars at the desired and precise temperature.

With constant sealing the inner layer is sealed without any defect to the backing material.


Click to watch a video of the HPL Rotary Sealer


Which is best? An impulse or a rotary heat sealer?


Medical Sealers



In general heat sealers can be divided up into a couple of categories. On the one hand you have the impulse sealers which often feature a jaw or clamp in order to make the seal. They require a manual operation.

As touched upon before the operator will place the bag between the heated bars, compress the jaw and wait a few seconds depending on the material. The bars and then lifted and the seal is then allowed to cool.

Impulse heat sealers are available in both table top and hand held formats.

A rotary heat sealer works slightly differently.

Here the packaging pouch is fed through a sealer either from the left or right side. A roller belt or band feeds the pouch between the sealing bars allowing heat and pressure to be applied.

This creates a consistent and optimal seal quality!

When making a decision you need to consider what you are sealing and what the requirements of the finished seal are.

If for example the bag needs to be kept completely sterile you should gravitate towards a rotary heat sealer. If not an impulse sealer machine may be sufficient.

When considering a impulse sealer it is important to remember that process of sealing pouches and packaging essentially involves a human, and so is exposed to human error.

Somebody must make the decision as to how long the pouch is compressed and so runs the risk of not allowing adequate time for an optimal seal.

Often this is not visible to the naked eye.

The pouch may hold the contents but the seal is poor with small gaps that compromise sterility and lead to defected product.

A rotary heat sealer eliminates this risk and the pressure that is applied remains consistent and and allows for consistency.


Is a Band Sealer the same as a rotary sealer?

Band Sealer

Essentially yes! But it depends on the specification. Band Sealer machines are often to referred to as rotary band sealer machines or continuous sealer machines.

They feature a motorized belt or band as opposed to roller trays which speed up the sealing time. This makes them ideal for mid to high volume sealing.

Most models can seal in excess of 50 pouches per minute depending on size.

They can feed from right to left or left to right. A vertical continuous band sealer allows the pouches to be sealed from top to bottom.


Horizontal Sealer

What about traceability?


For projects undertaken in a healthcare and pharmaceutical setting it is very likely you will require a rotary heat sealer. In addition to the improved and consistent seal quality you also have the option to print information on one side of the seal.

Many of these sealers feature a self contained printer which can print key information such as who made the seal and the and at what date and time. You may wish to add additional information such as the expiry date and the department responsible. Here trace ability is ensured in the event a mistake is made.

One example would be if a patient has contracted an infection during a surgical procedure. It may be determined the cause was a pair of contaminated scissors. The hospital can then trace back to where and when that particular instrument was sterilsed and sealed. The underlying cause could be anything from a faulty sealing bar to an incorrect setting but having the information printed on the packaging allows for trace ability & accountability.



Do I need a heat sealer with cutter or without?


Heat Sealer with Cutter

Heat sealers with cutter knives are for those who wish to make their own custom sized bags from film on a reel.

Often with lay flat tubing or another polythene material. Here you just measure the material to size and cut off any excess by closing the jaw and sliding the easy to use cutter blade.

Our most popular model here is the standalone table mounted HPL 450 or 630m.


Which are the best Heat sealers for plastic bags?

As above it will depend on the material of your packaging, the environment and the volume of sealing you need to do.

If you decide on a table top heat sealer the HPL 300 BMS & HPL 500 BMS are excellent mid range options. These are impulse bar sealers that feature interlocking magnets to ensure perfect seals for every seal.  Available in both 300mm & 500mm cutting lengths.

A good choice for high volume sealing would be the HPL 450, 630 & 1000 AS machines.

heat sealer for plastic bags


What is a barrier bag?

A barrier bag is a packaging format that contains non permeable material like aluminium foil or nylon. This type of packaging is ideal for goods that will be transported or stored long term.

A 3 side seal flat pouch is the most common barrier bag format. As well

Usually these are 3, 4 or 5 ply (layer) materials. This gives the packaging a low moisture vapor transmission rate (MVTR) when sealed optimally. You can also include desiccant bags or silica gel sachets to further increase product life span. When packaged properly goods can be stored without defect for years.

Why are Polyethylene and Polypropylene bags not ideal for long term storage?

Unlike the barrier bags mentioned above Polyethylene and Polypropylene based materials are porous. This means that regardless of thickness or gauge they will allow moisture, oxygen & gas into the bag over time.


What are the benefits of vacuum sealing?

There are numerous benefits to vacuum sealing. One is space saving. Once a product is vacuum sealed the packaging forms itself around the product to fit the shape, this minimizes storage space. Others include protection from contamination and extension of shelf life. Once the oxygen from the enclosure is extracted fresh goods last longer.


What is Modified Atmosphere Packaging (MAP) or Nitrogen Purge?

Modified Atmosphere Packaging is used to improve the shelf life of certain products. Mainly foodstuffs like fresh meat & fish or coffee & teas. A Nitrogen purge (or flush) can often be added as an optional extra too many vacuum chamber and vacuum impulse sealers as it removes moisture and harmful gases from the bag.

Decreasing the products exposure to atmospheric hazards like this increases shelf life.


What is the best way to determine which heat sealer is most appropriate and the settings that I will need?

If you are unsure which heat sealer is most suitable for your project we recommend that you send a sample pouch or piece of material for testing. In addition if you have any more information like a packaging specification this is always helpful, most manufacturers will advise on the approximate temperatures for the sealing of each film. It provides us with a good starting point in order to conduct some sealing tests.

If you prefer you can do this yourself once you receive the machine. Generally we recommend that you start off with a seal time of 2 – 3 seconds at 150 degrees Celsius. Then let the seal cool for 2x or 3x the heat time. This should give you a good indication of whether to increase or decrease the temperature & sealing time.


Are there any materials that cannot be sealed by Valdamark Heat Sealers?

Our heat sealers are not able to seal denim, vinyl, fibreglass or cellophane.


Does Valdamark provide an after sales service and replacement parts?

Yes. Valdamark supplies from stock a range of HAWO spare parts including those for the WSZ & ISZ models. Specifically this includes the most commonly used consumable parts like PTFE (Teflon) strips as well the heating elements, thermostats and welding bands.

Hawo Heat Sealers have a warranty returns rate of less that 0.05% of total sales. In the unlikely event your heat sealer does fail get in touch with us first to discuss this. If troubleshooting indicates a defect we will happily take the heat sealer back under warranty.


Does Valdamark calibrate any of the heat sealers?

Yes we do!  We offer a simple and convenient calibration service for all our medical sealer machines. We understand that down time is an important consideration for clients who rely on their machine for production continuously. We are flexible in delivering our calibration service and can often do this on site when arranged prior.

Our maintenance and calibration services are delivered in full compliance with BS EN 868-5 & ISO 11607-2. For audit assurance we issue a fully traceable certificate confirming seal strength and integrity.


Why a HAWO Heat Sealer? 

Hawo Heat Sealer machines are trusted by the worlds leading brands in a diverse range of sectors. Medical, Industrial, Life Sciences, AgroFoods and Textile are just some of the markets served by HAWO products.

HAWO GMBH is a globally active company that concentrates on future focussed heat sealing innovations. With many patents, trade marks and technological know how HAWO has become the world leader in it’s field.

All it’s innovations are geared towards the customer with precise and functional ergonomics built in to every machine.