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 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 standard bag or pouch that could contain identical monolayers. So you would need to seal just two layers of material.
Other packaging like coffee bags or gusset pouches may have several layers that need to be sealed at once. So, your sealer will need to be suitable for this.
What material will you be sealing ?
Many sealers can seal different types of materials, but it is important remember that some are not suitable for certain materials and different thicknesses.
Polyethylene including HDPE, LLDPE and PE
Polyethylene Terephthalate or PT
Cellulose or Barrier Foils.
What size sealer will you need ?
Sealer blades ( or jaws ) 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 maneuverability as the packaging can easily be positioned without overlapping the edges of the machine.
Our Heat sealing machines
Two types of heat ! Impulse Sealer and Constant Sealer
Impulse 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 be used for thinner gauge laminate materials.
Standard Impulse Sealers will suit most projects, being able to easily handle polythene films up to 600 gauge or 150 microns.
The Audion Sealboy is our most popular unit here. It’s fixed unit available in a variety of different sizes with or without a cutter.
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 but we would advise a trial 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.
Rotary heat sealers
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.
Barrier 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.
Which is best? An impulse or a rotary heat sealer?
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?
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.
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.
To crimp or not to crimp? The crimp sealer question.
The word crimp refers to the seal pattern on some bag machines. Its primarily there to improve seal strength and avoid de lamination of any multi layered materials.
Many people refer to this as the crisp bag sealer. Or the plastic bag crimper.
It’s the clients personal preference to have this or not.
The Audion Futura Cello 150C model is our most popular device.
This hand held crimper sealer features two serrated jaws and is suitable for cellophane, waxed papers, barrier foils and other metallized or aluminium laminates.
Do I need a heat sealer with cutter or without?
Heat sealers with cutter knives are for those who wish to make their own custom sized bags.
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 Audion Sealkid Heat Sealer 200m
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.
If you decide on a hand held heat sealer the
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.
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 to 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 weather 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, fiberglass 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 0.5% 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.