Technology of hotmelt application systems from H&H Klebetechnologie
Centerpiece of the H&H Klebetechnologie adhesive application systems is the scraper technology
For direct application of melted adhesive, most H&H hotmelt application machines are equipped with this application element. Each of these application elements is attached to a melting tank which melts the adhesive by heating. It can be controlled and heated electrically or by oil.
The centerpiece of the scraper technology is attached to the melting tank: Our coating element. The applicator element always consists of an applicator roller and two scrapers - also known as doctor blades. Particularly important is the distance between the scrapers and the application roller.
Distances between the scrapers can vary, depending on requirements, the type of adhesive and the required application quantity. The exact quantity in µ range is measured and adjusted by the H&H Technology. This precise technology ensures that the hotmelt evenly dispenses across the entire width of the rotating application roller. The thickness of the layer on the roller results from the distance between the wetted applicator roller and the first scraper in the direction of rotation. It is called a "Dosing scraper".
The substrate can now be directing the application roller with an individual pressure of the pneumatically operated pressure roller. But only where the coated roller is in contact with the material, the adhesive is applied cleanly, evenly and with and precisely to the contour. Adhesive that has not been applied remains on the roller and returns to the melting tank. A clean application pattern with no lost adhesive is always the result
With the H&H hotmelt applicator element, coating is economical and sustainable.
The second scraper, "Closing scraper", prevents uncontrolled escaping and leakage from adhesive. This is particularly important when the machine stops. Only an application element that is 100% precisely adjusted and designed by H&H guarantees a perfect, clean, and rational adhesive application.
Constancy through counter-pressure blocks
Scraper technology developed by H&H Klebetechnologie can process a wide range of adhesives with different viscosities. Whether adhesive, from 1,000 mPa or 250,000 mPa - H&H application systems can always apply this cleanly, evenly and precisely thanks to the interaction of pressure, application roller and correct processing parameters.
We also compensate the pressure of the toughest adhesive by means of the counter-pressure blocks developed by H&H, which are located on the wipers. Should the dosing scraper bend, the previously defined fixed adhesive application would present an impure picture.
We use effectively adjustable counter-pressure blocks to counteract this deflection. The deformation can be prevented and a clean application ensured by means of finely adjustable adjusting screws on the counter-pressure blocks of the scrapers.
The number of counterpressure blocks used on an H&H Klebetechnologie machine always depends on the roller length and the required application quantity. The H&H system is equally "resistant" to filled and unfilled adhesives.
Dosing roller technology from H&H Klebetechnologie
Dosing roller systems are also built and distributed by H&H Klebetechnologie. In dosing roller technology, liquid adhesive and pre-melted hotmelt is fed into the upper gap between the dosing and applicator roller. The adhesive is dispersed evenly over the entire width of the rotating rollers.
In the dosing roller technology, the application quantity can be determined, among other things, by the gap size between the two rotating rollers. In addition, the application quantity can also be influenced by setting different speeds of the dosing and applicator roller.
One of the rollers - the dosing roller - in the machine is always heated. Optionally, the second roller - called application roller - can also be heated. Always necessary when too much heat is extracted by contact with the material. This additionally heated roller therefore also makes it possible to create a uniform adhesive application under changing process conditions.
The pneumatically operated pressure roller can deflect in a controlled manner. In the event of thickness tolerances of the material to be coated.
The special surfaces of the steel rollers by H&H Klebetechnologie
The appearance of the application pattern and the structure of the adhesive to be applied is largely determined by the surface of the application roller. We at H&H Klebetechnologie have developed many different applicator rollers over the years. However, knurled rollers are used for the most common applications. Our customers use these with the most diverse types of knurling, depending on the material, adhesive and, of course, our application.
Surface examples
For example, a roller with a finely polished surface can apply very little adhesive very thinly. Other special "engravings" such as dot, strip, honeycomb or net-shaped and individual patterns can cover further very different adhesive application patterns.
Application rollers from H&H Klebetechnologie can apply full-surface films from smooth to rough. To minimize the adhesion of an adhesive to the applicator roller, these can also be especially non-stick coated. Coating is standard when processing PUR hotmelt adhesives.
