side seal is a packing device that converts a flat roll film into a three-sided bag. It seals both sides and the bottom. The fourth edge remained open for filling. You may have seen this type of package in disposable ketchup packets, shampoo samples packets, coffee creamer packets packets and drug unit dose packets. It is one of the most common pouch formats in soft packaging. The design is simple. The machine was sealed on three sides and left open. The product is then bagged. The last side can be sealed on the same production line or later in the production process.
This paper introduces what Three Side Seal Bag Machine is. It covers the two main machine types on the market. The working process of sealing, suitable material and the quality standard of the finished product are also described. It also includes what to check before buying a machine. Adopting Zhuxin Machinery and other well-known enterprises' production equipment. Founded in 1989, the company is a manufacturer of bags in 1989. It exports full film to thebag production line.
The Two Configurations Behind the Name
In the packaging industry industry, the use of "three-sided seal"is relatively lax, consumers will often get the "three-sided seal" statement. Buyers may be confused because two different machine types can produce similar looking pouches.
Pre-Made Pouch Machines (Bag-Making Machines)
The machine runs the film through a folding table. It has two side seals and one bottom seal. It can also use folding as the bottom. The machine then cuts each pouch. The output is a pile or roll of empty pouches. The pouches are then filled and sealed on separate filling equipment. Most of the machines listed as "three-sided baggers" fall into this category. They make bags, but they don't fill them.
Vertical Form-Fill-Seal (VFFS) Machines
In the packaging industry industry, the use of ``three-sided seal"is relatively lax, consumers will often get the ``three-sided seal" statement. Buyers may be confused because two different machine types can produce similar looking pouches.
Pre-Made Pouch Machines (Bag-Making Machines)
The machine runs the film through a folding table. It has two side seals and one bottom seal. It can also use folding as the bottom. The machine then cuts each pouch. The output is a pile or roll of empty pouches. The pouches are then filled and sealed on separate filling equipment. Most of the machines listed as "three-sided baggers" fall into this category. They make bags, but they don't fill them.
How a Three Side Seal Bag Machine Works, Step by Step
side seal is mainly divided into five stages in each production cycle. The process is similar for different machine configurations.
1.Film Unwinding and tension control
The packing film roller is mounted on the unfurling shaft at the rear of the machine. Common materials are PE, polypropylene, BOPP, composite film and so on. The film passes over dancer rollers and tension sensors. These parts keep the film flat and reduce wrinkles.
Proper tension control is important. Uneven tension causes folds to move. It can also cause the side seals to be uneven and cause printed registration marks to move in position. This can increase waste of materials during high-speed production.
2.Folding or Tube Forming
In prepackaged bags, the film passes through a folding plate, also known as a folding plate. The former folds the film in half along its length. The folds form the bottom of the finished pouch. This produces one of the three sealed edges.
On a VFFS machine, the former wraps the film around the molding tube. Film becomes tubes. Then seal the overlapping edges with a longitudinal seal. This creates the back slits of the bags under the eyes.
3.Heat Sealing on three sides;
The sealing section is the main part of the machine. Heated sealing jaws is compressed with a pneumatic cylinders or servo cam film. Heat melts the sealant layer. Pressure and residence time, then the film layers are glued together.
In sequential design, the machine is first side seals. If the bottom seal is separate, then it creates the bottom seal. In a simultaneous design, one inverted-U sealing jaw can complete all three seals at once.
Depending on the film material, the sealing temperature is usually 100–220° C. Each seal has its own temperature control. The bottom fold has two film layers, so it may need different heat settings from the side edges .
4. Photoelectric Registration
For printed film, a photoelectric sensor reads the registration number on the film. The machine then adjusts the film's position in real time. This helps the cutting blade land between two printed patterns.
Without registration control, the graphics may not stay in position. Cuts can also be made through the logo. Most modern machines automatically stop when the registration number is not detected. This helps prevent a lot of misprinting going to waste.
5. Cutting and Collection
Seal film moves to the cutting station. High-speed machines often use rotary knives. Eager blade can be used in BOPP, OPP and other films.
Cut pen strokes to separate each pouch. The finished pouches are then transferred to conveyor belts or stacking bin. Some machines also use a perforation wheel. This keeps the pouch in a rolling connection. This format applies to torn sachet strips used in vending machines and catering services.
What Films Can It Process?
The three-sided bag holder requires good heating and tension control. Each type of film requires a different seal setting.
Polyethylene (LDPE/HDPE) -Low melting point, a wide sealing range. Widely used in retail, food bags.
Polypropylene and BOPP – these materials have a high melting points. They need more precise temperature control. BOPP can also be used to shrink wrap and bakery packaging.
Laminate and aluminum foil-these are used in barrier pouches for coffee, medicine and food condiments. They require longer sealing times and precise pressure. Heat must pass through multiple layers without damaging the sealant.
Paper and coatings-these are becoming more common as brands use more recyclable packaging. Biofilms may require lower temperatures and slower production speeds to prevent blistering .
Typical film thickness is between 15 and 120 microns. Thicker laminate machines use stronger sealing frames and wider sealing jaws. Lightweight OPP machines, such as the RQL series from Zhuxin Machinery, are designed for high-speed hot sealing and thermal cutting. Applicable to OPP, BOPP,4etc.
Why Seal Quality Is a Science, Not an Afterthought
Sealing protects the product from the outside environment. Seal strength is an important factor for packaging engineers and managers.
The industry standard method for measuring seal strength is ASTM F88/F88M, or "Standard Test Method for Seal Strength of Flexible Barrier Materials." The test measures the force required to separate material strips containing seals. It can also determine the cause of seal failure. ASTM describes seal strength as a quantitative indicator of process validation, performance and control. This means that the bag maker should have a consistent seal during production, not just a strong seal from time to time [3].
For food packaging, the film must also comply with local regulations. In the United States, Chapter 21 of the Federal Code of Regulations regulates exposure to food as an indirect food additives. Parts 174 -178 include adhesives, coatings, polymers and production aids.
The main rule of the European Union is Regulation (EC) 1935/ 2004. It requires food contact materials to prevent harmful substances from being transferred to food. European Commission Regulation (EU) No 10/2011 also lists approved substances for plastic materials and sets overall migration limits .
If you export sachets to the US or EU, ask your machine supplier for documents linking the film, ink and adhesive systems to the regulations. Film suppliers are also required to produce compliance statements.
Machines can be made of substandard film into well-sealed pouches. Compliance depends on the packaging materials, not the setting of the machine.
Applications Across Industries
Pocket dust collector is small, leakproof and low cost. side seal are used in many industries:
- Food and spices-Ketchup, mustard, soy sauce, instant coffee, sugar, salt, spices and baking kits.
- Pharmaceuticals-sachets of powder, granules and liquids per unit dose. These products need to be highly sealable to meet regulatory requirements.
- Cosmetics and personal care-Shampoo, lotion and cream sample packs.
- Hardware and electronics-gadgets, fasteners and electronics that need dust and static protection.
- Logistics-Polymex Preferred Pack adopts self-adhesive sealing seal on three sides.
Zhuxin Machinery The RQL-600/800/1000 series shows the range of these machines. These side-sealed hot cutters can produce 40–198 bags per minute, depending on model. They can handle up to 600mm of sealing and cutting. They range in width from 580mm to 980 mm. They are used in products such as socks, towels, bread and jewellery .
How to Choose a Three Side Seal Bag Machine
Buyers simply look at the listed production speed and pick the wrong machine. Here are a few things to look out for before you buy:
1.Empty Pouches or Filled Pouches?
First, decide if you need a pre-made pouch machine or a VFFS line. The two machine types are different. They cannot replace each other. Product listings don't always make that clear.
2.Seal Width and Heating Capacity
A Wider seals provides stronger sealing. They also require more heating power and longer sealing times. Choose the sealing jaw width according to your product's barrier needs. Don't only choose based on the maximum size listed in the directory.
3.Changeover Time
If you produce a many SKUs, choose a machine that stores the formula in PLC. The system saves on temperature, bag length and speed settings. These settings can then be loaded again in a short time. Modern servo-driven machines can store product settings the HMI.
4.Frame Rigidity
The sealing process forces the machine repeatedly. A sturdy frame helps keep the sealing jaws alignment. Machines with cast-iron frames, such as the Zhuxin RQL series, can maintain a better chin over time. This can improve the consistency of the seal and prolong blade life.
V. After-Sales Service and online integration
Bagging machines cannot be used alone. We can also produce diaphragm blower, flexible printing press, cutting machine and other equipment suppliers, such as Zhuxin Machinery, can provide a complete production line. One vendor can handle the whole system. You can then adjust thickness of the film, print registration, and bag dimensions together.
Conclusion
The three-sided bagging machine swaps a roll of film for a large number of identical pouches. It is done by folding, sealing and cutting the film. The process looks simple enough. It requires precise tension, temperature and time.
If you need empty prefabricated pouches or padded sealing lines, the key points are similar. Choose the machine according to your own production process. Check that the film and seal comply with the food exposure rules of the target market. These include 21 CFR in the US, Europe Regulation (EC) No. 1935/2004 and European Union Regulation (EU) No. 10/2011. seal quality was tested using recognized methods such as ASTM F88.
Suppliers with long manufacturing experience and complete production line capabilities can also make the procurement process easier. Zhuxin Machinery, which has been in business since 1989, can help buyers adjust the production process from film to bags through a supplier's equipment.
