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What is the difference between a heat sealing machine and an induction sealing machine? This paper examines the difference in the case of an automated line.

Often, clients new to packaging approach Benefel asking for heat sealing equipment to seal their product without realising that this older, less sophisticated method of sealing a product is not what they really want.  In terms of machine versatility, pricing, safety and set up nearly all these clients are better served using induction seal machinery.

Below are some key differences in the sealing machinery and sealing process:

Heat sealing machinery disadvantages:

1. Products are sealed without their cap or lid in place.
2. Product handling is more complicated when automated as the products need to be transported, without spillage, in the sealing machine using cups or turrets in open containers.
3. Machinery is more dedicated to specific sizes of containers, given the complexity of transporting open containers.
4. Versatility of heat sealing machinery is limited and requires significant change parts if a different size or shape container is to be sealed using the same machine.
5. There is a physical source of heat that comes into contact with the container to melt the seal in place.
6. The machinery is often rotary in nature increasing the size and cost of equipment compared to induction sealing machinery.
7. The process cannot be started instantly as the physical sealing heat required needs the sealing element(s) to reach temperature.
8. Physical handling of the product means the machine has many more service and set up issues compared to the induction sealing process where there is no physical contact.
9. Heat sealing requires a larger sealing surface to work well; for instance if you look at a Yoghurt tub you will see the packaging is designed with a turned out flat rim to accept the heat sealing foil.

Heat sealing machine advantages:

1. The sealing material per unit is usually less than induction sealing material.
2. Products can be sealed without a lid or cap.  Note there are Capless induction sealing machines but they are not so common and are usually more expensive.
3. You can visually inspect each seal as there is no cap or lid covering the seal during the sealing process.
4. Very low cost plastic seals (without a metal foil layer) can be used.  This is a big advantage when the primary reasons for sealing do not include moisture and oxygen barrier requirements.
5. Larger diameter jobs beyond 70mm will use a large amount of sealing material per item and hence the availability of lower cost sealing films becomes a more significant advantage for heat sealing.

To list the induction machine advantages and disadvantages would be to simply reverse the above mentioned factors.  Nevertheless the benefits of induction sealing can be summarised below:

• Induction machines have a smaller machine foot print
• Induction machines are lower priced
• Induction machines do not need to touch or handle the product
• Induction machines are simpler and safer to operate having no physical source of heat
• Induction machines are versatile and can handle many different shapes and sizes of containers.
• Induction machines can be powered on and ready for production nearly instantly.
• Induction machines are much faster to adjust and set up for different jobs.
• Induction machines are far easier to move from one production line to another as they can simply be wheeled into place over an existing section of conveyor.

There are companies that are dedicated to converting old heat sealing machines over to induction sealing machines, whereas the reverse case does not exist pointing to the generally accepted opinion that when you need to seal a Jar or bottle the most likely method will be with an induction seal.

There is still a place for heat sealing usually limited to applications where the sealing diameter is more than 70mm and the volumes of the same size product are very large and changeover of sizes and shapes is not required.  The other main application for heat sealing will be where the product has no lid or cover and the sealing film is what is relied upon to complete the package.

 

Induction heat sealing is a simple non-contact process that transfers heat using the power of electromagnetic induction.  While it may sound daunting, it is used in a great number of industrial processes like welding, sealing and even cooking.

Induction Sealers

Induction sealers are also known as heat sealers. They transmit an electromagnetic field which creates eddy currents in a metallic foil attached to the bottle or the container. This foil is generally an aluminium based foil. This inner seal usually within the cap or lid is placed in the magnetic field and the eddy currents heat the foil seal.  A bonding layer laminated to the Foil layer and in contact with the neck or rim of the container melts and forms a bonding layer once the heating has stopped and the liner and container surfaces cool down.

Induction sealing machines comprise a power source, a sealing head or coil and a cooling system. There are two levels of Induction sealing machines we offer: Entry Level Low Cost Induction Sealing Machinery and High End Medium Priced Induction Sealing Equipment. In both levels of our induction sealing equipment we stay away from water cooling; all our units are air cooled.

We are committed to delivering the most technologically advanced and cost-effective solutions for your operation. Our application particular solutions make certain of maximum uptime and performance. Benefel’s unparalleled support and induction sealing innovations empower packaging operations around the globe.

Earlier, traditional induction sealers were cooled by water, and the power generator used to be at the floor level. This used to be connected to the sealing head, mounted above the conveyor, by combined electrical and cooling cables. Modern sealing machines are air-cooled. This provides for a more compact machine. And the entire unit can be mounted above the conveyor.

Innovation continues to push induction sealing technology forward. This innovation has led to not only smaller systems as electronics have gotten smaller but also simplified the induction sealer by eliminating the need for a water cooling system for most applications. Today’s induction sealer requires very little maintenance and has unmatched reliability. Induction technology is now available to seal containers without a rigid plastic cap! Whether you want to seal your product with or without a cap, inspect the package and then cap the package or if your application does not call for a cap(e.g. yogurt, juices) Benefel’s induction technology provides many benefits over the hot plate used in conduction sealing.

Induction sealing systems come in many different shapes & sizes. Your application and production requirements determine which system is right for you. Our SealerOn Induction Machine Range is designed for both laboratory testing , manual environments and slower line speed applications.  In addition, we offer The MeRo Induction Machine Range – High End Medium Priced Induction Sealing Equipment with unique features like adjustable width heat sealing tunnels and energy Transfer process validation measurements.  Whether your product is packaged at only a few containers a minute or hundreds of containers per minute, Benefel has an in-line system that will seal your product.

 

Product manufacturers across categories like household chemicals, cosmetics, pharmaceuticals, and food and beverage industry play an increasingly important role in meeting consumers’ changing needs and values. They need to ascertain that their products reach their consumers in top condition.  Poor merchandise state such as leaking and damaged containers, spoiled and contaminated products are major complications that put safety at risk.

Thanks to worldwide application knowledge and the most advanced production techniques, the ability to realize a perfect seal every time is now achievable. 

The use of the induction sealing system, when properly applied, can enhance the value of the product.  By making the container airtight (hermetic), it provides a tamper proof seal that prevents all the above mentioned problems while maintaining a professional overall look. The induction sealing system is also ideal to extend product shelf life and to preserve freshness that fosters consumer confidence.

What to look for in an Induction Seal:

• A good seal is achieved within minutes of the induction sealing process. For total sealing – induction foil manufacturers highly recommend 24 hours before the best end result is achieved
• Over Heating – Pay attention to any signs of scorching or melting inside the cap
• Under Heating – if the foil sealing layer did not melt and bond with the entire rim of the bottle or jar top neck surface.
• Proper Heating – is determined if the foil totally seals around the rim of the product and secondary cap lining materials, the bottle neck and the cap are not overheated.
• An experienced operator will know how warm a bottle lid should get before it starts to cool.
• An experienced eye will pick symmetric heat patterns in the induction foil and in foam backing material behind some induction foils

 Proper Induction Sealing is met if:

1. For non breakable containers, the seal can usually stand the force of dropping without the cap.
2. For easy-peel seals, the seal can be taken off without leaving behind a foil ring.  For permanent weld seals the foil will need to be cut.
3. No leak after being dropped

 How to achieve a perfect induction Seal?

To realize a consistent product seal, container, cap closure, lining material, and induction sealer should be well matched. To find the right combination, we recommend that you consult with your cap closure lining material supplier or Induction Sealing equipment supplier.  To record the energy transfer window for good sealing results we recommend and supply the Linepatrolman™.

Container

The majority of induction sealed containers are plastic, however, glass containers can be induction sealed too –

usually for dry products like coffee.  The choice of container type is made based on the product compatibility, marketing and logistic considerations. 

Cap Closure

The cap closure needs to have a flat inside area to hold an induction liner.  Screw on caps allow for a wider range of hard and soft cap lining materials.  Snap on caps are generally more suited to softer cap lining material.  If using a two part induction sealing material where a foil separates from a backing material, the cap may need to have features that retain the backing material when the two part induction material separates as the container is opened.

Lining Materials

The determination of the appropriate induction seal material is dependent on the following:

• What the container is made of
• Product content
• Duration of usage
• Cap Tolerance any Type (eg Screw on or Snap on caps)
• Method for which the lining material will be inserted into the cap
  

Induction Sealer

Choosing the right machine for your needs is an important task. In determining the right supplier, be sure that they:

• The supplier can offer technical advice on the induction sealing process and if necessary participate in the closure and container development side of things where necessary.
• The supplier of the machinery either supplies or can also advise on the supply for the induction lining material.
• The supplier ONLY provides CE safety certified equipment.  Induction sealing equipment involves very high electric currents and electromagnetic fields.  Places like China and India are producing and supplying very low cost options WITHOUT CE certification.

 

 

Induction Heat Sealing is a packaging process that does not physically touch the product.

Making use of the near magical properties of magnetic fields, without any physical contact, an induction machine is able to heat and seal a specially formulated sealing material to the rim of a bottle or container.

Often referred to as induction machines, bottle sealing machines offer the manufacturer and consumer alike a level of product integrity that cannot be achieved with a plastic cap alone.

 

The induction process is achieved using high levels of current passing through a sealing head coil back and forth at a high frequency.  This process creates a localised magnetic field that goes up and down at high frequency.  This magnetic field can pass through the air and through plastic but when it gets to metal it “induced a current back and forth in that metal.  This induced current mirrors the current in the sealing head coil that created the magnetic field in the first place.

A bottle sealing machine relies on the bottles being fitted with caps or closures which have had an induction heat sealing material placed into them prior the cap being applied to the bottle.  This induction heat sealing material usually comprises layers that include a backing to give the seal some rigidity, a layer of aluminium to “catch” the magnetic field and a sealing layer which is heated by the aluminium.  The sealing layer is heated and then, having passed the area of the cap sealing machine, given a chance to cool and “set” onto the top rim of the bottle.

What keeps the induction cap sealing material in the cap or lid prior to the cap or lid being placed onto the bottle or jar?

The most common technique is where the cap is designed to have retaining clips or a retaining ring above top cap threads.  The liner is pushed into the cap and it “flicks passed” the retaining feature in the cap.  Usually, enough room is left for the liner so when the cap is twisted off the liner does not have to twist with the cap.

How does the liner come out of the cap after it has been induction sealed to the bottle?

After the induction sealing process the sealing layer melts and then sets to form a bond between the lining material and the bottle or jar rim.  When the consumer twists the cap off container, the retaining feature of the cap effectively “flicks passed” the foil bonded to the container.

Bottle sealing with the induction process avoids the need to handle the product or packaging films during the production process.  It is a process that avoids direct heat and surfaces too hot to touch and bottle sealing machines can be set and adjusted very easily – especially if they are like the MeRo induction machines with energy transfer feedback or if you use a Line-Patrolman which provides this feedback measure for your cap sealing machine setting.

Often the first place a product will spoil is just under the cap due to ingress or escape of gases and/or liquid.  The metal layer within the induction sealing material serves the dual purposes of a conduit to take the magnetic energy from the bottle sealing machine and convert it to heat energy required to activate and set the sealing layer and it serves as a packaging sealing layer with barrier qualities of near zero levels for transmission of gases and liquids.  The barrier properties of foil are what saves large shipments of product from being cosmetically damaged by leakage and they are also what keeps products smelling so fresh and fine powders remaining so dry.