How a pedal heat sealing machine closes a bag

The bag rests on the shelf in front of the jaws. The operator lays the bag mouth flat across the bar, then presses the foot pedal. This closes the jaws on the bag; on the impulse models it also starts the heating.

Heat and pressure join the two film layers, and the seal sets as it cools. A foot pedal sealer leaves both hands free to hold the bag straight and flat.

First, you fill the bag with the product. Next, you lay the mouth of the bag flat across the bar using both hands, making sure there are no folds. Then, you press the foot pedal to close the jaws. On the constant heat model, you hold the pedal down for the seal time. On the impulse models, you hold it until the light goes out and one to two seconds more, then release the pedal and take the bag away; the seal reaches full strength as it cools.

It is important to leave enough empty film above the contents of the bag. This extra space allows the mouth to lie flat across the bar without pulling product into the seal area. If the contents are too close to the sealing line, they can get trapped in the seal, which weakens it and can cause leaks. For example, when sealing a bag of powder, make sure the powder sits well below the mouth before sealing.

The shelf in front of the jaws supports the filled bag during sealing, so the weight of the contents does not pull on the seal while it is still warm. Always hold the bag mouth stretched with both hands as the jaws close. Any fold or wrinkle in the mouth is a weak spot where the bag may open later.

Impulse heat sealer or constant heat: how they work

The ZONE300D is a constant heat sealer. The bar stays at the set temperature, ready for every bag. This model seals thick bags and aluminium-laminated (foil) bags. The seal is 300 mm long and 14 mm wide, and the temperature is adjustable from 0 to 300 °C.

The ZONE450F and ZONE600F are impulse heat sealers. A wire in the bar heats only while the jaws are closed, then cools under pressure. The seal sets before the bag is released. Both seal PE and PP film and multi-layer film. The ZONE600F closes wide bags up to 600 mm in one press. If you need a foil bag sealer, choose the ZONE300D.

The ZONE300D produces a seal that is 14 mm wide, which is wider than the 2–5 mm seal made by the ZONE450F and ZONE600F. A wider seal is useful for heavy or bulky contents, as it gives the seal more area to carry the load. For example, a heavy bag of granules up to 300 mm wide is closed on the ZONE300D, where the 14 mm seal carries the weight of the contents. The impulse models, with their narrower seal, are suited to standard PE and PP bags.

The ZONE300D keeps its bar hot the whole time it is switched on, so it is ready as soon as the pedal is pressed. The impulse models draw their heating power only during the short pulse when the jaws are closed, so between bags they use no heating energy.

With the constant heat bar, it is important to keep hands clear of the sealing area, as the bar stays hot even when not sealing. Always switch the machine off during longer breaks to avoid accidental burns and to save energy. After switching the ZONE300D on, wait until the bar has reached the set temperature before sealing the first bag.

An impulse bar is cold between bags, so there is less risk of accidental burns during setup or bag placement. The seal cools under pressure before the jaws open, which gives a flat and neat finish on thin film. This process adds one to two seconds of waiting per bag, but it means the seal is set before the bag is moved. In summary, foil laminates and thick bags up to 300 mm wide are sealed on the ZONE300D; PE and PP bags of normal thickness go to the ZONE450F or ZONE600F, which also take bags wider than 300 mm.

ZONE300D, ZONE450F and ZONE600F: comparison table

The table below compares the ZONE300D, ZONE450F and ZONE600F heat sealers by seal length, heating type, films sealed and main settings.

To use the comparison table, start with the film row: if you need to seal foil bags, only the ZONE300D is suitable. Next, compare the seal length with your widest bag mouth, then the seal width, which is wider on the constant heat model. Finally, check the supply row, because the ZONE300D runs on 220 V only, while the impulse models can run on either 110 V or 220 V.

Which bags a plastic bag sealer closes, by model

The ZONE300D seals PE and PS film and multi-layer laminates, including aluminium-laminated bags. The ZONE450F and ZONE600F seal PE and PP film and multi-layer film. The seal length is 300 mm, 450 mm or 600 mm depending on the model.

A poly bag sealer must cover the full width of the bag mouth in one press. The ZONE600F closes sacks, liners and covers up to 600 mm wide.

Foil laminates are used when you need to keep light and moisture away from the goods inside the bag. These bags are sealed on the ZONE300D, which seals aluminium-laminated and other multi-layer laminates. A foil bag keeps moisture out only if the seal is complete along the whole mouth, so check each seal by eye.

Bags with side gussets have four layers of film at the folds, which makes sealing more demanding. The gussets must be folded evenly, and the whole bag usually needs a little more heat or a longer heating time than a flat bag of the same film, because the seal has to go through four layers at the gussets. For example, when closing a gusseted liner, make sure the folds are flat and raise the setting if the seal at the gusset is weaker than the rest.

Thicker film needs more heat or a longer heating time to seal properly. Thick bags go to the constant heat model, as its bar stays hot and can deliver enough heat for the seal to hold.

If you are sealing a bag with a zipper, always seal above the zipper, never across it, because the zipper does not seal and keeps the mouth from lying flat.

Settings and handling: impulse sealer and constant heat

On the constant heat model, set a low temperature and raise it in small steps until the seal holds. The seal time is how long the pedal is held down. On impulse sealers, start with a short heating time and add tenths of a second until the seal holds.

Lay the bag mouth flat across the bar with no folds. On impulse models, wait one to two seconds after the light goes out, then pull the bag away sideways, never forward: the seal has set but is still warm, and pulling forward can open it.

To find the right setting for a new bag, use a real sample. Start with a low temperature or a short heating time, seal the bag, let it cool, then pull the two sides apart. If the seal peels open, raise the setting a little and try again. The right setting is found when the film tears beside the seal instead of the seal itself opening.

Signs that the setting is too high include the film shrinking away from the bar, turning thin or burning through, or sticking to the PTFE cloth. If the setting is too low, the seal peels open with little force. Check the setting again when a new delivery of bags arrives, because the film thickness can differ from one batch to the next. After many bags in a row the jaws of an impulse model warm up, so a heating time that was right at the start may later be a little too long; check a seal now and then during a long run.

It helps to write the correct setting for each bag type on a card and keep it at the machine, so the next operator does not have to start from zero. On the constant heat model, count the same time for every bag, so each seal gets the same amount of heat.

Pedal heat sealer or band sealer: which fits

A pedal heat sealer closes one bag at a time with heat and pressure. This suits packing stations where bags are filled and sealed by hand. A band sealer carries bags between belts and seals them without stopping, which fits lines with many bags per hour.

The three heat sealers here are pedal models for closing bags by hand: as an industrial heat sealer at a packing station, each one closes a bag up to the length of its bar in one press.

With a pedal sealer, the operator controls the pace of work. Filling the bag and laying it flat on the bar take most of the time, while the sealing step itself takes only a few seconds. If the time spent filling and preparing the bag is longer than the sealing time, switching to a faster machine will not speed up the packing station. A pedal sealer also takes bags of different sizes one after the other without any change, while a band sealer is set up for one bag size and is meant for a steady flow of the same bag.

Band sealers come in vertical versions for filled bags that stand upright and horizontal versions for flat bags. Many band sealers can print a date or code into the seal during the process.

Because a vacuum packing machine removes the air, it is the choice for goods that must be kept away from air; a pedal model closes the bag with the air inside. The pedal models here stand on their own column, with a shelf for the bag and a foot pedal that leaves both hands free to position the bag. This setup suits long bars and heavier bags better than a small sealer placed on a table.

Which materials can be heat sealed

A heat sealer joins two layers of thermoplastic film, such as PE or PP, by heat and pressure. A laminate seals when its inner layer is a sealable film, and that includes foil laminates; aluminium-laminated bags are sealed on a constant heat sealer.

Paper or cardboard alone does not seal. With printed or laminated bags, the inner layer decides, not the outside: a bag printed on the outside seals like its inner film.

As a rule, both layers must be the same plastic: PE seals to PE and PP to PP, but PE does not seal to PP.

Ask your bag supplier for the material and thickness of the bag, and check if the inner layer is sealable. This information decides which model and settings you need. For example, if the supplier confirms a thin PE film, the impulse models are the ones to look at, and the heating time is then set to suit the film thickness; a thick PE bag goes to the constant heat model.

A paper bag with a PE lining seals like PE: the heat passes through the paper and the two PE linings melt together inside the seal, so it needs more heat or time than a PE bag. The ZONE300D can also seal PS film, while the impulse models are made for PE, PP and multi-layer film.

What makes a seal hold on a bag

A seal holds when the heat, the pressure and the time suit the film. The temperature or the heating time is set on the machine for the bag material and its thickness, and adjusted until the seal holds without burning or shrinking the film.

The bag mouth must be clean, dry and flat across the bar. Folds or powder in the seal area weaken the seal. A wide seal carries heavy contents and looks even. A narrow impulse seal uses little energy because the bar heats only during the seal.

The pressure needed for a good seal comes from the pedal and the top pressure pad. If seals start to fail in one place along the bar, check the pad and the PTFE cloth at that spot first: a damaged pad gives uneven pressure, and a worn cloth makes the film stick and heat unevenly.

A good seal is clear and even, without wrinkles, bubbles or burnt spots. To keep the seal area clean while filling, fold the top of the bag outward like a cuff or use a funnel, so powder or liquid does not touch the inside of the mouth where the seal will be. With liquids, keep the bag upright so the liquid stays away from the mouth until the seal has cooled. A good seal is the same along its whole length; a weak spot at one end often means the bag was not laid straight.

The seal gains its strength as it cools, so do not pull at the bag or load the seal while it is still warm. For heavy contents, making two seals one above the other gives an extra margin of safety; the second seal goes a little above the first, on film that is still clean and flat.

What decides the price of a bag sealing machine

The price of a bag sealing machine depends on the heating type, the temperature or time control and the build of the frame and the jaws, more than on the length of the bar.

The current price of each heat sealer is shown on its product card above, and all three come with a 12-month warranty. For a quote, use the Get offer button on the product card; the Add to inquiry button collects several products into one request.

The running cost is small: it is the PTFE cloth, the heating wire on the impulse models and the top pressure pad. Keeping a spare set of these parts at the machine avoids unplanned stops at the packing station.

The ZONE300D keeps its bar hot with two 175 W elements, so it is always ready to seal. The impulse models, ZONE450F and ZONE600F, draw 800 W or 1000 W, but only during each short heating pulse. Where bags are sealed at intervals rather than continuously, the impulse models use less energy over a shift.

How long the sealing bar has to be

The sealing bar must be at least as long as the bag mouth is wide. If the bar is too short, the bag needs two presses, which leaves a weak spot where the seals overlap. The whole mouth has to lie flat across the bar in one press.

To choose the right bar length, measure the bag mouth lying flat and compare it with the bar: the ZONE450F takes bags up to 450 mm wide, but a bag that fills the bar right to the ends is hard to lay down straight. If your widest bag is close to the length of a bar, the next longer bar makes the work easier and avoids weak spots at the ends.

When measuring bags with side gussets, fold the gussets in before measuring the width. A long bar also closes small bags: you can seal two or three small bags side by side in one press, as long as their mouths lie flat and do not overlap. The ZONE300D, ZONE450F and ZONE600F offer bar lengths of 300 mm, 450 mm and 600 mm.

What to check before you order a heat sealer

Check the widest bag mouth you need to seal, the film and its thickness, and whether the bag is a foil laminate. Count how many bags you close per hour, measure the space at the packing station, and make sure there is a single-phase socket with a separate earth. Note also whether the bags are filled with powder, liquids or heavy goods, because that decides how the mouth is kept clean and whether a double seal is needed.

The comparison table above then shows which of the three fits: foil bags up to 300 mm wide point to the constant heat model, wide sacks to the longest bar.

Ask the bag supplier for a few sample bags as well, so the setting can be found with real bags on the first day.

If sealing becomes the slowest step at your packing station and the number of bags per hour keeps growing, a band sealer that moves the bags through without stopping fits better than a pedal sealer.

Plan the space around the machine. The footprint ranges from 345 × 480 mm for the ZONE300D to 700 × 570 mm for the ZONE600F. Allow extra room for the operator and for a table to hold filled and empty bags on either side. Heavy bags need a place to rest right after sealing, close to the machine, so the seal is not loaded while still warm.

Care and wear parts for your heat sealer

Never close the jaws empty: it burns the PTFE cloth. The PTFE cloth and heating wire (on impulse models) are wear parts. Replace the top pressure pad if the seal becomes uneven.

Keep the bar and PTFE cloth clean and dry. Never clean them wet or scrape hardened film off with anything hard. All models run from a single-phase socket with a separate earth. No compressed air is needed.

The PTFE cloth covers the sealing bar and prevents the film from sticking during sealing. When the cloth is burnt, torn or has film stuck to it, the seal becomes uneven and the film may start to stick to the bar. In this case, replace the cloth to restore a clean, even seal. For example, if you notice the bag is hard to remove or the seal looks rough, inspect the PTFE cloth first.

A heating wire that has burnt through will not seal the bag at all, so keep a spare wire and a spare cloth at hand for the impulse models. Always clean the bar when it is cold, using a dry, soft cloth to wipe off any film residue. Switch the machine off and unplug it before you change any wear part, to work safely and avoid electric shock.

Questions about heat sealers

Can these heat sealers close foil or aluminium bags?

Yes, on the ZONE300D: as a constant heat sealer it seals aluminium-laminated (foil) bags up to 300 mm wide and multi-layer laminates. The impulse models are made for PE, PP and multi-layer film.

What is the longest bag mouth these machines can seal?

The ZONE600F impulse heat sealer closes bags with a mouth up to 600 mm wide in one press. The ZONE450F seals up to 450 mm and the ZONE300D up to 300 mm.

What power supply do these heat sealers need?

All three heat sealers run on an ordinary single-phase socket with a separate earth. The ZONE450F and ZONE600F can use 110 V or 220 V, and the ZONE300D uses 220 V.

Do these heat sealers need compressed air?

No, none of these heat sealers need compressed air. They are pedal sealers and require only a single-phase electric supply.