Heat Sealer Machines
Heat sealing or bag sealing machinery is used to seal polythene and plastic bags as part of a packaging process. Heat sealing is used in packaging for a huge range of products of many different dimensions, shapes and materials. It is one of the most widely used ways of creating a protective enclosure which also facilitates handling.
There are multiple different types of machinery available for heat sealing, and PPMA members and exhibitors at the annual PPMA Show provide hugely valuable insights into the options available for producers and packaging companies.
Plus, if you're looking for labelling machinery to complement any packaging processes, you can find more information and PPMA exhibitors in the labelling machinery sector here.
What are the types of heat sealing machinery?
The two core types of heat sealer are impulse sealers and constant sealers. The two types have been developed for different applications, but both machines work on the basis of the application of electrically heated bars under pressure to form a closed seal for plastic bags.
Impulse heat sealers
Impulse heat sealers have one or two heating elements. The elements are heated only when they are closed around the bag. The jaws of the sealing machine press the heating elements against a heat-proof rubber pad for the length of time required to create a secure seal. A short cooling time allows the plastic to fuse properly. The elements are coated or covered to ensure that the bag does not stick to them when the jaws are released.
Constant heat sealers
Constant heat sealers maintain the heat in the elements, so that they are always ready for operation at an accurately controlled temperature. The sealing operation is the same as in impulse sealers, but can be constant rather than intermittent. Generally, constant sealers can operate at a higher temperature than impulse sealers so are more suitable for thicker, or layered, thermoplastic packaging materials.
Impulse heat sealers vs constant heat sealers
When deciding whether to buy an impulse sealer or a constant sealer, it is important to understand the heat required for the packaging you wish to use, how many packs you wish to produce, and their size.
Impulse heaters are the entry point for heat sealing machines and, depending on their specification, are entirely suitable for businesses packing up to 20 products per hour, or possibly more. They are also relatively low on electricity usage because they are only heated while the seal is formed. They are also an easy way of sealing on more than one side of the pack, simply by manually turning the pack.
Constant sealers are more expensive, and use more power, but they are capable of sealing heavier gauge plastics, films with a foil content, or multiply films. They are also designed with automated feed options and accelerated production. For commercial businesses producing 50 or more packs per hour, constant sealers are likely to be the best option.
Which materials are used in heat sealing?
Heat sealing only works with thermoplastic materials which soften under heat and harden when cooled. Many packaging operations use plastic films supplied in tubes which are sealed and cut, while others use open bags, pouches or single sheet films for sealing bespoke packaging.
Commonly used bagging materials include:
- Polyethylene including HDPE, LLDPE
- Polyethylene Terephthalate (PET), also known as Mylar
Materials which require higher temperatures achieved by constant heat sealers are:
- Aluminium foils
- Barrier foils
- Laminate foils
- Coated papers
- Cellulose films
- Cellophane films
The choice of material used in a bagging operation will depend on the products being packed. For example, in the food sector, lighter products such as cereals are generally bagged in light polyethylene or polypropylene. Sterile products which need high levels of protection from moisture and the environment are frequently packed in foils, as are various foodstuffs including ground and whole bean coffee.
Handheld heat sealers
Handheld bag sealers are manually operated and require the placing of bags into the jaws of the machine which is then switched on to heat and form the seal. Hand held equipment is a versatile solution for businesses packing relatively few products, and does not require significant amounts of space.
Buyers should look for handheld machines which are light in weight and designed with safety in mind. Controls too offer significant operational advantages such as timers for sealing and cooling. Hand held sealers are usually impulse machines, but hand held constant machines are also available for packaging materials which require higher temperatures.
Tabletop heat sealers
Tabletop sealers are compact sealers which are more comfortable to operate than handheld sealers. They take away the need for holding the sealer and can achieve higher throughputs. Table top machines are also available with integrated cutters which accelerate the creation of finished packs.
Foot operated heat sealers
Operation by a foot pedal allows packing staff to control sealing machines and leave their hands free to lift or position products on the sealer. Floor standing heat sealers can usually be adjusted for operation from a sitting or standing position. Both impulse and constant machines are available in foot operated models.
Rotary heat sealers
Rotary heat sealers are a type of constant heat sealer with bags or bagging materials fed by a horizontal roller or belt conveyor, with vertical feed systems used for liquid or powder products. They require limited manual handling and so are frequently used for sterile packing. Rotary sealers are also capable of achieving significantly higher outputs than handheld or table top machines and so are used in larger packaging operations.
Vacuum heat sealers
Heat sealing is a feature of most vacuum packing machines. Once a vacuum has been created in a chamber or external vacuum machine, the container needs to be sealed immediately, and heat sealers are an integral part of the design of the equipment. In chamber vacuum machines, the heat sealer operates within the vacuum chamber. For external vacuum packers, the heat sealer is integrated into the machine’s gripper bar.
Thermoform Heat Sealing Machinery
Thermoforming involves the heating of a plastic sheet to a temperature at which it becomes pliable. This enables the plastic to be formed into a particular shape for its purpose. It is also in widespread use in the pharmaceutical industry for blister packaging for pills and other medication in which a foil cover is heat sealed over the base plastic material.
Find Heat Sealer Machine Suppliers
See a full list of PPMA Member companies that supply a comprehensive range of heat sealer machines.
Take a look at the different processing and packaging machinery in thePPMA Show's Machinery Spotlight, where there is a variety of different machinery to fit different requirements.
Heat sealing machinery FAQs
What type of products can be packed in heat sealed bags?
Heat sealed bags and pouches work very well for a multitude of food, drink and pharmaceutical products, as well as for general purpose packaging. Buyers should be aware of whether the weight or dimensions of their products will be suitable for heat sealed bagging, or whether more robust types of packs need to be used.
What packing material can be heat sealed?
The vast majority of heat sealed packs are plastic based bags, foil pouches and stand-up pouches. Heat sealing is also used to affix foil covers and lids to containers and trays, frequently as part of a thermoform packing line.
Are heat sealed packs crimped?
Some heat sealers come with the ability to crimp the seal with a serrated finish. Crimping improves the strength of the seal and reduces the likelihood of damage to laminated packing materials. Many producers choose crimping for a more professional appearance for their packs.
Can heat sealed bags be printed?
Pre-printed films and foils are frequently used in heat sealed packs to carry branding and consumer information. More sophisticated constant sealing machines are available incorporating a print facility for batch numbers, use by dates and other variable information.
How much does a heat sealing machine cost?
Simple handheld impulse machines can be sourced for a few hundred pounds or less, which can be perfectly adequate for a home-based artisan business producing a few dozen packs a week. Costs go up with better performance in terms of temperature, the machine’s size, the quality of the machine’s materials and components, and the range of materials which can be sealed. For most commercial businesses, a table top machine will be required, with costs in the region of £500 to £1,000. State of the art, high throughput rotary heat sealers are likely to take costs into the thousands, depending on size, capacity and controls.