Hot-plate welding of plastics. Four hot-plate welding units to weld components of small and big dimensions and obtain leak-tight articles.
The hot-plate welding, also called mirror welding, is the most suitable welding technique for the joining of plastic articles of small and big dimensions or plastic articles needed to obtain leak-tight articles.
During this kind of welding a plate/mirror is heated up until it reaches the temperature necessary to melt the materials to weld. The temperature variates depending on the material and in some cases it goes beyond the threshold of 400°C. The two components to weld are brought close to the hot-plate until they touch it; the heat makes the components malleable without anyway changing their chemical and physical characteristics. When the joining area has reached the melting temperature, the plate is quickly withdrawn and the components are joined to be welded together.
The articles that can be hot-plate welded can be produced by means of injection moulding, extrusion moulding, compression moulding, thermoforming, blow moulding, suction 2D/3D (2k) and rotational moulding.
Hot-plate welding is the most used technique to weld components of small and big dimensions necessary to obtain leak-tight articles, such as, for examples, pipes and tanks of various kinds.
GS Finishing Machines has developed four kinds of hot-plate welding units. All units can be supplied with a device to clean the surface of the hot-plate that works efficiently at every cycle. The cleaning device avoids the contamination of the following welding, ensuring the repeatability of the best welding quality. Besides, the hot-plates can be processed with a non-sticking treatment or be supplied with interchangeable, quick-change non-sticking tapes.
The types of hot-plate welding are the following:
PNEUMATIC HOT-PLATE WELDING UNIT WITH MECHANICAL STOPPERS WITHOUT PROCESS MONITORING
It is the simplest unit, since it does not check the precision of the movements.
PNEUMATIC HOT-PLATE WELDING UNIT WITH MECHANICAL STOPPERS WITH PROCESS MONITORING
This unit checks that the mechanical stoppers have been reached either during the melting of the surfaces to weld and the joining of the components.
PNEUMATIC HOT-PLATE WELDING UNIT WITH MONITORING OF THE MEASURE
This unit checks either the distance of the components before the start of the welding and the melting of the components by reaching the previously set measures. Besides, it carries out the dimensional check of the melting measure of the components and the dimensional check of the joining measure. It can reach switch times lower than one second (switch time < 1 second), so granting the best welding quality.
ELECTRIC HOT-PLATE WELDING UNIT WITH MONITORING OF THE MEASURE
This unit carries out the same checks of the pneumatic hot-plate welding unit with monitoring of the measure. The difference is in the functioning: it is an electric unit, not a pneumatic one. The electric movement grants its greater precision and higher speed, with a reduced energy consumption. It can reach switch times lower than one second (switch time < 1 second), so granting the best welding quality.
The hot-plate welding with monitoring of the measure, be it with pneumatic or electric movement, allows to automatically adapt the melting depth and joining depth of the components to the welding plane. The blow-moulded articles, during the cooling phase, are subject to geometrical variations that change the distance between the welding plane and the welding unit. The monitoring of the measure nullifies the effect of such alterations, avoiding the production of faulty articles. The productivity of the whole operation of hot-plate welding is therefore increased.