Quick and Easy Thermal Cleaning of Multi-Layer Blown Film Die Heads
SCHWING Technologies provides safe and fully automatic systems for large and heavy blown film die heads up to 1.70 meters in diameter
Complex multi-layer blown film die heads are becoming increasingly important in the production of high-quality films in the food industry. Production of films with up to eleven layers is complex from an application and cost perspective. These multi layer films offer multiple types of protection in terms of strength, UV stability, guaranteed barrier layer, and sterility, which is of particular interest to the food and packaging industry. This combination of different properties in a film explains why a perfect blown film die head is the prerequisite for perfect product quality.
Production loss and rejects
What if the film quality diminishes and the die head needs cleaning? “Production losses and rejects when restarting the system, both can easily reduce the efficiency and productivity of a capital-intensive investment like a blown film equipment by eight to ten percent per year,” stated Thomas Schwing, Managing Director of SCHWING Technologies. In addition, the consequences of insufficient cleaning quality in the form of carbon residues and flawed surface smoothness of the tool itself also must be taken into account. These problems are typical for cleaning by hand and using chemicals or in inappropriate burnout furnaces.
Conventional cleaning: a financial trap
If it is necessary to stop the blow film system and clean the blown film die head, a considerable number of man-hours are needed to clean the entire die head depending on its size and complexity. More time is needed for disassembly, testing and reassembly of the nozzle since each layer of the die head has to be cleaned individually. Besides the known disadvantages associated with cleaning by hand, such as damage from scratches or material distortion, reduced surface smoothness and just sufficient tool cleanliness if applicable, several days of production loss is a considerable burden. Such a loss in production for a blown film production system that costs several million dollars to purchase therefore represents a significant cost factor.
Thermal vacuum pyrolysis cleans quick and safe
Compared to conventional methods, cleaning of a large multi-layer blown film die head in a thermal vacuum pyrolysis system at SCHWING Technologies takes only two to three days. “Costs attributed to maintenance, system shutdown and production loss are therefore significantly reduced,” emphasized Schwing, adding that smaller die heads and machine parts can even be cleaned in a single work day.
The VACUCLEAN System cleaning process
The thermal cleaning process for the VACUCLEAN System from SCHWING Technologies can be loaded with the complete blown film die head. “Our system cleans blown film die heads with a diameter of up to 1.70 meters and a weight of up to twelve tons in a gentle but effective way by carefully melting the remaining plastic inside the blown film die head under a vacuum,” explained Schwing. In a second cleaning phase, the plastic that still stucks on the part is exposed to more heat into a pyrolysis process with fully automatic monitoring and then oxidized with more oxygen. In this highly effective cleaning method, Conical stacked mandrel multi-layer heads are cleaned as a unit before being dis- and reassembled. It takes a maximum of about 30 hours to clean an assembled blown film die head consisting of five layers.
Blown film die heads in a modular plate design have to be disassembled prior to the cleaning to reduce cleaning time.
Maximum productivity of the blown film die system
Due to the relatively short cleaning times of the SCHWING systems, more and more blown film manufacturers are starting to regularly clean their production tools in order to ensure the productivity of their production plants. Schwing: ”It is always more economical to opt for the comparably short production stoppage for die head cleaning since improved productivity only comes from a longer die head lifetime and less production loss thanks to more stable quality.” This gentle cleaning causes maintenance costs to decrease and the downtime and lifespan to increase. Most of the companies that replace their manual cleaning processes with SCHWING systems thereby optimize their cleaning process and get a return on their investment within a year.
- elimination of expensive cleaning materials
- perfectly reproducible cleaning results with each cleaning
- lowest overhead (electric power, water)
- extremely low maintenance cost
- easy to install and operate
- redundant integrated security checks and clear operating processes
- overheating protection with a direct temperature control of the product in need of cleaning
- environmentally friendly systems with clean exhaust air
- no organic contamination of the cooling water
SCHWING Technologies GmbH
M +49 173 9774780
T +49 2845 930 146