Polypropylene welding is one of the most popular methods for processing this material. With the help of welding, it is possible to connect virtually any polypropylene elements: from sheet material to pipes of different diameters.
Table welding polypropylene pipelines.
The technology of such welding consists in the bonding of structural elements by thermal means without changing the chemical composition of the material. This process is carried out with or without filler material. High-quality compounds can be achieved in the case when the treated surfaces will be brought to a viscous state using local heating, followed by pressing them together. After the welded zone cools, the individual elements form an integral part.
Methods of welding sheet polypropylene
Depending on the welding equipment used, the connection of polypropylene can be carried out in several ways:
- using a building hair dryer;
- polyfuse (butt).
Figure 1. Manual extruder - tool designed for extrusion welding of polypropylene.
The first type of welding is carried out using a special device - a manual extruder (Fig. 1). This device is small in size and comes with various nozzles. It is convenient to use it for welding large items that have a complex structure. Typically, an extruder for polypropylene is equipped with an integrated or built-in air supply mechanism, through which the plastic in the welding zone is heated and softened.
The technology of extrusion tool welding involves the use of an additive in the weld zone, which in most cases is polypropylene wire. Hot air produces heating of the welded surfaces to a viscous state, and the additive passing through the extruder is also heated and mixed with the base until a homogeneous mass is formed. With this method of welding, even thick-walled elements can be joined, while obtaining a high-quality seam.
Figure 2. Welding with a construction hair dryer is carried out with the aim of joining sheet material with a thickness of not more than 20 mm.
Welding using a construction dryer is carried out under the influence of a jet of hot air heated to a temperature of 170-180 ° C (Fig. 2). This method is used to join sheet material with a thickness of not more than 20 mm. In this case, the weld has a relatively small mechanical strength. Therefore, it is recommended to use a building dryer for connecting small-sized elements that will not be subject to heavy loads during operation.
Polyfusion welding is performed using movable tables. The welded seam obtained in this way will have a sufficiently high strength and reliability. The butt method can be used to connect individual elements of almost any thickness.Back to table of contents
Instructions for welding sheet polypropylene
Before starting work, it is necessary to prepare the equipment, the workplace and the filler material. The tool is connected to the power source, the additive is inserted into the extruder holder, and the workplace is cleaned of dirt and dust.
The scheme of welding pipes made of polypropylene.
After that, you can proceed to the preparation of the welded surfaces. To do this, the material lies on the table, and its edges are processed with fine-grained emery paper, since the rough surface will have better adhesion properties than a smooth base.
After the completion of the preparatory process, heating the extruder tip to the desired temperature, the welder moves it along the seam, as when welding with electrodes, filling the joint with a melted additive. At the same time, the wire feed rate in the weld pool is adjusted manually or automatically. After 5-10 minutes after completion of work, the welded sheets can be used as intended.Back to table of contents
Welding of polypropylene pipes
At installation of modern systems of water supply and heating, polypropylene pipes are commonly used. To date, a technology has been developed for their installation, with which it is possible to assemble elements of various diameters.
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The device for welding of pipes from polypropylene
Figure 3. An apparatus for welding polypropylene pipes includes a thermostat, a knob and a heating plate.
Welding of such products is carried out using a special welding machine, which has a fairly simple design, and the principle of operation resembles an ordinary iron (Fig. 3). This device consists of a temperature controller, a heating plate and a handle. The heating element has two holes, in which in the process of work the welded elements are installed.
Using nozzles of different sizes, pipes of various sizes can be welded. In the standard set there are 4 sets of such nozzles: 20, 25, 32 and 40 mm. Their work surfaces have a Teflon coating, so the manufacture of such a device with their own hands is impossible. Welding nozzles can be machined at home on a lathe; however, without a Teflon coating, plastic will constantly stick to them.Back to table of contents
Preparation for welding of polypropylene pipes
In addition to the welding machine for welding plastic pipes, you must also prepare:
- a sharp knife or facer for cutting the pipe edge at an angle;
- alcohol for degreasing.
Polypropylene pipe mounting technology.
The welding nozzles are attached to the welding equipment. After that, having connected the device to an electrical supply, with the help of a temperature regulator, an operating temperature of about 260 ° C is set on it. The time for heating the nozzles to the required temperature depends on the ambient temperature. To avoid damage to heated nozzles during work, they must first be cleaned with a rag made of non-synthetic material.
After that, the condition of the cutting element is checked by making several cuts on an experienced piece of plastic. This should make an even cut without burrs. Otherwise, the tool must be sharpened on the grinding machine. Before welding, all elements are carefully inspected for any defects. The welded ends of pipes and fittings into which they are inserted are thoroughly cleaned and degreased.
Then, using a special tool, the pipe walls at the prepared end are mown at an angle of 45 °. This will avoid scratching the plastic when inserting the pipe end into the fitting. Having previously inserted a pipe into the fitting, a marker marks the depth of its entrance. It should be borne in mind that the pipe is inserted into the coupling not to the stop. To avoid expansion of the pipe in the welding zone, a gap of at least 1 mm is left.Back to table of contents
The process of welding polypropylene pipes
Before starting the welding process itself, the ends of pipes and fittings should be degreased again. At the heated nozzles first put on the fittings, and then the pipe itself. After that, you need to wait for some time to warm up the connecting elements.
During heating, it is strictly forbidden to turn parts, as this will lead to their deformation and failure.
The heating time of polypropylene pipes can be calculated from the table below.
|Outer diameter of pipe, mm||Heating time, sec.||Connection time, sec.||Cooling time, min.|
The heated parts are removed from the nozzles and are interconnected by precise and fast movement, without turning them around their axis. The pipe is inserted into the fitting to the mark that was previously applied. Details hold in the correct position for 20-40 seconds. In most cases, this is enough to cool the plastic.
When welding polypropylene products, the performer must have some skills in welding. Therefore, if you are not confident in your abilities, it is better to seek help from a specialist, since the presence of any errors in the welding process can lead to serious consequences.