How to weld plastic film with your own hands

Sheet polypropylene is a modern construction material with excellent characteristics. It is used in construction as an insulating material; in addition, it is used to make swimming pools, various containers, ventilation ducts, and is used for finishing individual treatment units.

Welding polypropylene is more reliable than mechanical fastening of sheets and gluing. Heating to the melting temperature ensures the strength of the joints, the seams are sealed, do not allow water to pass through, and do not deform during operation. There are several technologies for temperature bonding of sheet polymer, all of which will be described below. For this purpose, special equipment is used; working with it requires certain knowledge.

Properties and types of polypropylene

Composite and monolithic slabs are created from a polymer material, obtained by rolling, which compact the porous structure, give shape, and create a smooth surface. Main characteristics of the sheet:

• high tensile strength, compression, torsion;
• low specific gravity, no more than 0.92 g/cm 3 ;
• small expansion coefficient, maintains structure homogeneity in the temperature range from +80 to -40°C;
• environmental safety, does not emit harmful components;
• chemical neutrality to aggressive environments of acidic and alkaline nature;
• hydrophobicity: the material does not absorb moisture;
• UV resistance;
• dielectricity.

The material is easy to install using fasteners and can be cut, milled, welded, or glued. The sheet is available in three types:

• dense – has a homogeneous structure;
• cellular – loose, has soundproofing properties;
• foamed - used as insulation.

Welding technology

During temperature bonding, the structure of the polymer is not disturbed; the adhesion of the parts being connected occurs due to the process of interdiffusion. Welding polypropylene sheets involves heating the joint to a viscous-flowing state. When choosing equipment, it is necessary to take into account that when heated slowly at the joints, the material shrinks, and the quality of the seam suffers as a result. The welding temperature depends on the type of tool. For installation of sheets, the polyfuse method is used, when the joints are heated. Another connection is made using an extruder. You can heat polypropylene with an air gun (hair dryer).

Having the necessary equipment, you can join the sheets with your own hands.

Methods for manual welding of polypropylene sheets

During installation, two tools are used: a welding extruder for polypropylene and a hair dryer. Polypropylene wire or welding rod is placed between the sheets to be welded. It is selected according to the type of material being installed and must correspond to it in terms of the class of material and type of manufacture.

To weld polypropylene with a hairdryer, you need a high-power tool; heating is carried out for 5–10 minutes. Before this, it is necessary to prepare the surfaces of the parts to be joined: sand them with fine sandpaper to form uneven surfaces. Then the edge is cut at an angle of 45°. For continuous laying of the rod, a nozzle is used; a welding hair dryer is usually equipped with them. It doesn’t take long to make them from tin yourself. During the process, the joint heats up to 180°C, so sheets up to 20 mm thick are mounted with a hairdryer for welding polypropylene. For sheets over 16 mm, extruder welding is applicable; this is a more reliable joining method. The tool heats the sheet up to 270°C; it is equipped with special attachments that are used when installing complex geometric shapes. They need to work quickly so that the sheet does not straighten out. If there are two nozzles on the unit, it is not recommended to turn on both at once.

The principle of operation of the extruder is to heat the rod to a homogeneous consistency, while simultaneously heating the joint and extruding the extruded polypropylene. There are models of extruders where granules can be placed instead of a rod. They are softened in a plasticizer and pressed into the working area. The result is a very high quality and durable seam.

Automatic welding

Welding machines have been created to connect sheets. This welding equipment creates a smooth, diffuse seam by touching the joint with a heating element. An automatic soldering iron is needed for large amounts of work. The temperature is regulated depending on the structure of the sheet; the machine can weld polypropylene sheets with a thickness of 16 mm or more.

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Professional welding devices

For large-scale work (for example, to create covers for large greenhouses or for commercial activities), it is recommended to use professional polyethylene welding devices.
The advantages of these devices are that they allow flexible adjustment of parameters of pressure, temperature, and speed of movement along the seam. If you are working with the same batch of polyethylene, then by setting the required values ​​once, you can carry out the welding process at high speed. Devices for welding often have setting and tension rollers, which allow the film sheets to be connected to be pulled at the same speed, which has a beneficial effect on the final quality of the seam.

Industrial devices are produced in various types. They can have contact heating or heating carried out by hot air.

Working with large areas of material is economical when choosing a welding connection, since there is no need for adhesives or tape. Productivity and accuracy of work increases significantly. The low melting point and flexibility of the material allows the connection to be made by welding at home. The resulting joint strength mainly depends on the temperature and cleanliness of the surfaces being joined.

Bonding polypropylene sheets

Products with uneven surfaces are bonded chemically. This method is rarely used due to the fact that polypropylene is a difficult-to-glue material, it requires a special composition, traditional mixtures for plastic are not suitable, you need to pay attention to this. There are several types of glue:

• thermoactive based on polyphenolic resins or two-component, with a hardener or hardens when heated;
• thermoplastic one-component, the curing temperature must be indicated on the packaging.

The second problem with gluing is the preliminary marking of all parts before assembly; any mistake will lead to a large loss of material, and the work will have to start again. Marks are made on the ends of the parts to be joined so that the surface remains clean.

Let's sum it up

Typical welding mistakes that beginners make:

1. Wet and dirty joints reduce the quality of the connection; they can get dirty when laid on a flat surface, so this is also cleaned.
2. Wrong choice of filler rod; it is important to know the markings of the sheet before purchasing it. Letter symbols indicate the type of polymer: BS (block layer), V (foamed), G (homogenized), M (monolithic), PP (polymer).
3. Uneven heating of the working area and the additive; if the rod is soft, it will be difficult to press it between the elements being welded, it will bulge, and it will be easy to pull it out. If the additive is colder than the sheet, wrinkles will form at the seam.
4. Low or high speed of adding the additive: at low speed, deposits will form, at high speed, the seam will tighten.
5. To check the strength of the connection, the cooled seam is heated with hot air, then all defects become noticeable.

Soldering technology

Welding of different parts of a polyethylene film occurs by exposing its edges to a temperature equal to the melting point of the material, followed by tight compression of the layers.

The compression of molten polyethylene connects the parts of the elements at the molecular level, forming a strong weld seam.

However, in order for this seam to be reliable and withstand the load, you need to use suitable welding equipment, as well as observe the nuances of the technology. It is important to maintain a suitable temperature level, which ranges in a narrow range from 130 to 160 degrees Celsius.

Despite the fact that the film polymer compound does not look much like metal in appearance, the rule of thoroughly cleaning the surface also works with it.

Particles of foreign inclusions can disrupt the molecular structure of the junction of two films. Therefore, surface cleaning plays a key role in preparation for welding.

In addition, the following rules must be observed:

1. All parts of the material that will be soldered must be made in one batch
2. The melting temperature during welding must not be violated. An underestimated temperature will create a weak connection, an overestimated one will deform the material.
3. Re-welding of edges that have already been heat treated is not permitted.

Also, the quality and strength of the film seam is influenced by the tool with which it is created. You need to choose the right welding device. It is advisable to take one that will have fewer problems in handling.

Main characteristics of polypropylene

This material is produced industrially from macromolecules of an isotactic structure, and the process of formation of polypropylene in the form of sheets is as follows: the molten material is passed through rollers. Polypropylene is characterized by its use in the creation of various containers, large-diameter pipes, it also has insulating properties and in this area it has also found active use.

Let us note the main characteristics characteristic of sheet polypropylene:

• Does well in humid environments
• Differs in mechanical strength,
• The material is resistant to various chemicals: alkalis, acids, salt solutions.
• Not afraid of ultraviolet rays.

Another important feature characteristic of polypropylene is the versatility of its installation. This material can be cut and joined in many ways. Currently, the most commonly used are the following:

• Mechanical. It involves the use of fasteners. It is worth noting that a structure made in this way will not have high thermal insulation properties.
• Gluing. This method is very popular because the material is in good contact with mechanical substances, and the glue will not damage it in any way.
• Welding polypropylene sheets. Using this method, you will get a high-quality and durable connection; a special tool for welding polypropylene will help with this.

Technologies for welding polypropylene

• extruder welding,
• welding polypropylene sheets with a hair dryer,
• connection using a polyfusion method (similar to resistance welding).

Let's take a closer look at each of the technologies.

The first type of welding is based on the use of a special apparatus - a manual extruder to connect parts. The device is small in size and comes with different sized attachments.

It is well suited for connecting three-dimensional parts that have a fairly complex structure. For example, welding of membrane roofing is very often carried out using this machine. It is also successfully used as a machine for welding PVC pipes.

Most often, the extruder used for welding polypropylene is equipped with a mechanism responsible for supplying air, through which the plastic in the welding area heats up and becomes softer.

The technology for welding polypropylene using the extrusion method must be carried out with a mandatory condition: in the weld area it is necessary to use an additive substance, which is usually polypropylene wire. Hot air heats the surfaces of parts being welded to a viscous state. The additive that passes through the extruder also becomes hot and is mixed with the base until a homogeneous substance is obtained. This method allows you to connect very thick parts, for example welding a membrane roof, as well as materials whose thickness is small. Therefore, welding of polyethylene sheets is also very often carried out using this technology.

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roof welding with extruder

The next method is welding polypropylene sheets with a hairdryer. An important and integral component of this technology is the flow of heated air (170°C-180°C).

construction hair dryer

This method has found its application in fastening parts whose material thickness does not exceed 20 mm. Such indicators are typical for polyethylene sheets. In this regard, it becomes clear that the seam that is ultimately formed will not be very strong. Therefore, welding polypropylene sheets using a hair dryer can only be used if the parts being joined are small in size and will not be subject to heavy loads in subsequent use.

The main equipment for polyfusion welding of polypropylene is special welding moving tables. Two sheets are placed on the machine, then they are well fixed with a special clamping device. The person performing the work must set the thickness and length of the elements that will be welded. Next, the ends of the sheets are pressed tightly against the heating element; when the desired temperature is reached, this heating element leaves the welding zone, and sliding tables press the parts. The result is a very reliable and high-quality seam, which, in terms of its technical and operational characteristics, is the best obtained by other methods.

Hot gas welding

When welding with gas, all the heat comes from the heated gas, which already transfers it, coming out of the nozzle of devices and hot air guns of various designs. In this case, as a rule, the coolant is argon, carbon dioxide, nitrogen and, of course, air. The choice of gas depends precisely on the properties of the plastic that will be welded. For example, some types of plastics are highly susceptible to oxygen, and therefore better seams are obtained when choosing a gas like argon.

The technology for welding plastics with gas provides two options: with the use of filler material and without its use. When a rod is used, its diameter is usually 2 - 6 mm. The additive must be made from the material that is planned to be welded. In some cases, special plasticizers are added to the rod to improve the quality of welding.

The diagram shows: a - welding without nozzles, b - welding with a nozzle for hard thermoplastics, c - welding with a nozzle for soft thermoplastics, d - welding with a nozzle for hard and soft thermoplastics. 1a - standard nozzle, 1b - productive nozzle, 2 - base material, 3 - pressure roller, 4 - filler rod, 5 - guide channel, P - direction of pressure on the filler material, V - welding direction.

The main technological parameters of gas welding using a rod include:

• Gas flow and temperature level
• Materials used and rod cross-section dimensions
• Feeding rod angle
• Additive clamping force
• Angle of the heating apparatus to the plane of the part
• Speed ​​of welding work performed

The outlet gas temperature should not exceed 50 - 100 degrees Celsius higher than the viscous flow temperature of the polymer. The distance between the nozzle and the material should be 5 - 8 mm and maintained statically throughout the entire welding process.

If the angle of the rod is more than 90 degrees, the material placed in the seam will elongate and may be damaged during cooling. At an angle of less than 90 degrees, the rod will heat up faster than the polymer material, while the consumption of the rod will increase, and internal stress will arise in the seam. The strength of such a seam may decrease.

The angle of inclination of the burner axis to the plane of the products is 55-65 degrees, and then decreases to 45 degrees. In this case, the gas jet is directed at the base material, because its mass is greater than the mass of the rod. Welding speed can fluctuate greatly and can reach up to 15 m/h.

conclusions

In this way, you can connect not only polypropylene sheets, but also PVC films, HDPE sheets, and parts made of sheet plastic.

You should choose a welding machine based on what material you are joining and what the welded elements will be used for. You can do the welding yourself and choose: a hair dryer, an extruder, and also weld using the polyfusion method.

One of the most common methods of joining polypropylene is welding. This technology is the most popular and effective, this is explained by the thermoplasticity and strength of the materials. Welding of polypropylene sheets occurs due to their joining end-to-end or at right angles. You can also use an extruder, hair dryer or butt welding machine for joining.

Welding of polyethylene and polypropylene (PE, PP)

Materials such as polyethylene and polypropylene are the most common thermoplastics due to their basic properties. These are common polymers that are inexpensive and easy to weld using hot welding methods. The scope of application of these polymers is also huge, from films and pipes, to insulation, parts for construction and even food containers and containers.

It is important to note that not all types of welding are suitable for PP and PE. So, for example, it is impossible to weld with high-frequency currents, as well as when using solvents, which is due to the structure of these materials. But the use of hot air devices (or extruders), on the contrary, is encouraged.

Polypropylene sheet: nature of the material for the workpiece

This material is produced by squeezing polymer granules out of special holes. This technology allows you to end up with a sheet of any length and width. The leaf itself consists entirely of granules. The coating of such material can be either glossy or matte; if the sheet is coated with gloss, then it is covered with a film on top.

The main advantages of polypropylene are:

• dielectricity;
• sufficient hydrophobicity;
• resistance to abrasion;
• chemical strength.

Due to its special characteristics, welding polypropylene sheets is not a very voluminous process and is accessible. The entire welding process consists of bringing the edges of the material to a viscous state and pressing firmly against each other. Such a mechanism will help to obtain a solid part in the future.

Diffusion welding

Before starting work, it is necessary to prepare the workplace and all the material. To ensure that the gluing seams are as smooth and unnoticeable as possible, you should approach the process with complete seriousness and choose the welding method that will be most accessible and convenient for you. One of the most effective ways to join polypropylene sheets is diffuse welding. Such a mechanism is connected on a specially equipped welding machine.

Welding of polypropylene sheets occurs by placing two parts on the machine and fixing them. The ends of the sheets will be pressed against the heating element. To obtain the best effect, the sheets should be heated for a long time. After reaching the required temperature, the sheets are pressed using a locking mechanism. The seam obtained using welding equipment will be the strongest and most reliable.

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Very important for such welding is cleanliness and low humidity in the room; the air temperature should be warm. One of the main advantages of the seam will be not only its strength, but also the speed of obtaining high-quality material. This method is suitable for sheets of any width, and makes it possible to weld polypropylene sheets into rolls. When there is a lot of work, a welding machine will become an indispensable thing.

Welding with heating devices

One of the simplest methods of heat transfer is direct contact of the plastic surfaces being welded with the heating device itself or (in the case of air devices) heated air jets. Due to the simplicity of the technical process and the availability of devices and accessories for them, they are widespread.

• First, a warm-up takes place as the first stage. In this case, the melted edges are securely connected to each other.
• Contact between heated plastics and parts to be welded is maintained with a certain force for some time.

During heating, it is necessary that the contacting surfaces have penetration to a certain depth. This is also necessary in order to avoid working with any uneven surfaces.

There is a list of technological parameters for welding plastics:

• Heating element (or medium) temperature
• Heating duration
• Pressing force of the tool to the part
• Compression force of welded parts
• Duration of pressure after completion of welding

It is extremely important to clean the contact surfaces as much as possible to produce a quality weld. Because inclusions of other materials, dirt, dust inside the seam will negatively affect its reliability. If the surface is covered with oily secretions, they are removed with appropriate solvents (safe for the polymer itself). If it is impossible to clean, or the edge of the object is too uneven, it is simply trimmed to create a smooth, clean cut.

Welding using an extruder

This method requires the presence of a special tool - an extruder. This machine is equipped with various attachments that allow you to weld the most complex and bulky structures. The small size of the equipment is also a huge advantage. The extruder is equipped with automatic supply of warm air, which allows you to soften the sheets and avoid any damage during welding. Working with this method requires efficiency in action, since due to the high temperature (about 270C), deformation is possible near the inner layers of polypropylene.

This process does not require a separate room and connection is possible directly at the workplace, due to the compactness of the device. The seam obtained using an extruder is the second strongest after a welding machine. The disadvantage of this method is the need to connect polypropylene of the same composition and class, otherwise the seams will be weak and uneven.

Extruder welding

Another type of welding is possible, using an extruder, which is produced with a finished melt. And instead of special “frying”, the heat of the molten filler material is immediately used to create the seam.

Welding is carried out only if the temperature of the melt is 50 degrees higher than the temperature of the base material being welded. There are two types of welding: non-contact and contact.

With the non-contact method, the pressure is carried out with a special roller, while with the contact method this occurs under pressure from the extruder nozzle itself, as shown in the figure.

Welding polypropylene sheets with a construction hair dryer

To weld polyethylene sheets with a hair dryer, you will need a high-power construction hair dryer and thin polymer sheets, as well as polypropylene wire (selected for the size and thickness of the sheets that need to be joined). An important factor is the selection of material; sheets and wire must consist of the same class of materials. Neglecting this point will significantly affect the quality of the resulting seam and its strength, since the hair dryer will not be able to simultaneously bring different types of materials to the same required temperature.

For normal joining of sheets, they must be placed on a flat surface and the edges must be sanded. An important point in preparation is cutting the edges at an angle of 45.

The process of heating the hairdryer and melting the rod takes approximately 5 to 10 minutes. Next comes the welding process itself. A plastic rod is inserted into the nozzle of a welding gun and, while filling the seam, is continuously fed into the weld zone.

After following all procedures, the combined material can be used. The resulting seam when welding HDPE using a heat gun is less strong than when welding with a machine or extruder, however, this method will be ideal for joining material with a small thickness.

Welding from a battery: is it possible?

Is welding possible with a 12 Volt battery? This question is asked by all owners of dachas and garages who still do not have a centralized power supply. Also, the voltage may simply not be enough to power an average power inverter. This is where doubts begin... On the one hand, you can remove the battery from your car and power the inverter, and then put the battery back. On the other hand, many doubts arise. What quality will the seam have? Will my inverter burn out? Is it possible to use the battery in a car later?

From our experience, we can say that welding from a battery with your own hands is quite possible. We won't say that car batteries are ideal for powering an inverter, but they can be an excellent backup option. All car batteries have a decent power reserve, so in theory they can power a simple household inverter.

Bonding polypropylene sheets

Gluing polypropylene is a very labor-intensive process that requires special training. This is due to the fact that this type of plastic is especially difficult to glue. There are a large variety of adhesives on the modern market that can glue plastic together without any problems; the main issue will be the choice of a special solution. Special preparation for gluing the material will consist of pre-assembling all the parts in order to put the necessary marks, because incorrect connection of polypropylene sheets or a simple mistake in the process can cost you damaged material.

The main recommendations for gluing and welding polypropylene with your own hands are:

• It is necessary to purchase glue, paying attention, first of all, to its brand, but not to the price. Your experience in this matter will be an additional bonus for you. Sometimes glue from a high price category may be inferior in quality to cheaper analogues;
• It will be very important to pay attention to sharpening and processing the edges of polypropylene sheets; if this requirement is fulfilled correctly, the seam will turn out very neat;
• choose the welding method depending on the width of the sheet, as well as its size. The more correctly the joining technique is chosen, the stronger the resulting seam will be.

Recommendations

Before welding PVC with your own hands, you need to study the operating instructions and operating modes of the device. Different manufacturers may have different modes for the same films, because welding also depends on the flow rate of hot air.

It is preferable to use Teflon or silicone rollers as rolling rollers. There will be no sticking when the molten PVC flows out.

Welding PVC film for the manufacture of swimming pools has its own characteristics. First you need to prepare the geotextiles. It will protect the film from linear deformation and friction against the pool bowl.

Cutting materials must be carried out at temperatures above +10 ⁰C, built-in parts must be mounted in advance. When welding, a special hair dryer is used with automatic control and maintenance of the required temperature of the hot air flow.

Before welding, the surfaces are thoroughly cleaned with a solvent. The modes of the hair dryer and installed attachments are selected in strict accordance with the parameters of the PVC film. Welding pool bowls is a labor-intensive and responsible process that is recommended to be entrusted to professionals.