Die Drool Contamination Minimized


Grossostheim, Germany, August 25, 2014 – PSG Automatik Plastics Machinery has developed a tool to minimize the contamination of plastic strands due to deposits on the die plate...

Grossostheim, Germany, August 25, 2014 – PSG Automatik Plastics Machinery has developed a tool to minimize the contamination of plastic strands due to deposits on the die plate.

PSG Automatik Plastics Machinery (a Dover Company) is an established player in the processing of plastics. While the company’s pelletizing systems remain much favored for their performances in challenging applications, the German manufacturer also supplies many auxiliaries. Enter Automatik’s ground-breaking “Hot Air Knives”, (HAK) which the company has kept on refining over the years.

It is widely known that even a small amount of polymer, fillers or reinforcements such as glass fibers will almost invariably lead to die drool or fiber beards build-up around the die holes. These remains eventually burn and then collect on the strands, thus contaminating the end product. Such occurrences most likely will cause complaints from the end user and in the worst case the return of the product.

Many companies have introduced solutions to circumvent this problem by way of either mechanical cleaning - meaning that the process has to be stopped -, or drool prevention, which utilizes different die hole outlet geometries. Some attempt to prevent the build-up of polymer and glass by burning off the deposits with an open flame. The latter method carries with it the inherent risk of subsequent damage to the equipment and a burn hazard for the staff.


Automatik Plastics Machinery has been hard at work to develop an alternative solution that not only allows its customers to conduct operations safely but also increase the profitability of the plant without the need to interrupt production. The Hot Air Knife has been specially designed to reduce the deposits to an absolute minimum.

The HAK is placed directly at the die plate and thus avoids the build-up of such deposits that are causing contamination. It works like any air knife, except that the compressed air is preheated. The air volume and pressure are mechanically regulated, while the temperature of the compressed air is controlled electrically. The device simultaneously distributes the hot compressed air across the entire operating width of the die head. It acts through the combination of the high air velocity and the temperature of the air, which is above the melt temperature, blowing or melting away unwanted residues and deposits efficiently and precisely. Customer feedback has been overwhelmingly positive, with a large US conglomerate itself particularly pleased with both the high quality and the reliability of the HAK, as deployed at one of its international plants.

“Thanks to Automatik’s solution, the risk of contamination has been reduced by 80 to 90%, thus highly increasing the quality of the final product,” mentions the process engineer at the customer’s location. “The HAK was installed a while back and has been working reliably ever since the installation and has not caused any problem. After mounting the air flushing system, it can clean most of the dirt that has accumulated around the holes of the die plate during production. In the meantime, it also decreases the speed of accumulation under the die plate. This way, the possibility of contamination is reduced to a minimum and as a consequence, this also favorably impacts the staff’s workload,” further explains the engineer.

The specially-designed Air Knife can be either fully integrated into the machine control system or manually operated. In addition, it is offered in various widths to cover a variety of die head dimensions, from 100 mm up to 900 mm.

Automatik Plastics Machinery is constantly developing new products to allow its customers to make production safer and to increase the productivity of the pelletizing operations. To learn more about Automatik and its Hot Air Knife, please go to www.maag.com. For more information on Pump Solutions Group (PSG®), visit www.psgdover.com.