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Machines can be modified or specially built in accordance with the vision and needs of the customer. Zemat Technology Group machine offer is not limited to single machines. We realize any complex designs and projects, such as automated production lines equipped with the most modern industrial automation.
High-frequency generators are a source of high-frequency energy necessary in industrial capacitive heating processes. For many years, these generators have been an attractive alternative to conventional heating. They allow to significantly reduce the duration and energy consumption of technological processes when dielectrically lossy materials are processing. High frequency generators are used, among others, to supply pneumatic and hydraulic presses, chamber and continuous dryers. High-frequency generators are used in the wood industry for:
With using Zemat machines, it is possible to alternate the operation of high frequency generators with more than one output device, e.g. with two hydraulic presses. Zemat HF generators are made with the use of commonly available power triodes from leading European manufacturers. The output power and operating frequency are selected individually to the technological needs of the user.
Wood processing with presses is placing the raw material in a mold installed on the table of a hydraulic press and closing the mold until the pressure force is from. This force should be between a few to several kilograms per square centimeter of the material surface. The form is connected via metal tapes – waveguides – to a high-frequency generator, whose task is to heat up the processed material. The principle of heating can be simply compared to a microwave oven, where only food is directly heated. The required shape is formed in a quite short time with the use of special tooling called molds.
In gluing process, glue is the heated material – and to be more precise, the water contained in it. Glue is heated up to the polymerization temperature (80-110° C) within several dozen seconds to several minutes. The next couple of minutes of holding the material under pressure consolidates the shape of the product given by the mold and completes the chemical processes in glue.
Total time of the process is usually between 2 and 20 minutes, depending on the thickness and surface of the load and the amount of glue applied. The surface of the loads can be up to 2 m2, and the thickness up to 100 mm. It is important that the glue heating time (generator operation time) takes from 30 to 50% of the entire process time. As a result, the energy consumption of the process is reduced to the necessary minimum, as the energy is released directly to the load in a controlled amount and for a given time.
A common used solution is supply of two presses from one high-frequency generator alternatively. This is due to the fact that the heating and seasoning times are approximately equal.
Depending on the shape of the final product, the mold is closed only in the vertical plane – flat products or large radius arcs. Products with small radiuses and more complex shapes often require additional pressure in the horizontal plane, which improves the force distribution over the entire surface of the product and protects the mold against damage.
The forms in which the processed material is placed are made of plywood or wood. The working surface is covered with a thin aluminum sheet in order to evenly supply energy from the generator to the processed material. Making molds from very cheap materials (often in-house made) makes this production method very price attractive, especially when making short series or developing new patterns. In the case of the production of plywood, floor panels and other flat products, the forms are flat boards with appropriate dimensions.
In the drying process, the water contained in the wood is heated. This applies to both water of natural origin, the so-called capillary (this heats up the fastest) as well as water from mechanical processes, e.g. steam pressure soaking in bending processes.
The duration of the process depends on the thickness, area of the batch, initial moisture and expected final moisture. Drying bent elements (after the pre-bending process) means closing them in a mold of the required shape. The mold, similar to ones used in the gluing process, are made of wood and covered with a thin aluminum sheet.
Straight elements are dried between flat plates of the required dimensions. Flat or curved elements with a large radius can be dried in a layer system, and with the appropriate construction of forms, in a system similar to a two-shelf press.
The use of high-frequency technology with presses gives savings in the price of the tooling. Wooden forms covered with aluminum sheets are several times cheaper compared to traditional forms made of full aluminum or steel. Other advantages are the significantly increased speed of the production cycle and lower electricity consumption.
Furniture manufacturers are often interested in other types of machines produced by the Zemat Technology Group: machines for cardboard boxes production. Boxmat Boxmakers are ideal for making short and medium series of boxes. Each furniture factory produces many types of furniture, and these are often non-standard products that require appropriate protection in with cardboard for transport. The possibility of making boxes on demand with the right size and only in the needed amount is very attractive to them. BOXMAT machines are often found as part of the machinery park in furniture factories when the producer wants to reduce production and transport costs.
List of products that can be made on Zemat machines: