System to measure the bead size in the nip of a roll stack


Whatever you produce thermoplastic film or sheet the bead in front of the nip of the roll stack is mainly responsible for the quality of the end product. So for the processor it is of great help to receive an exact information about the bead size distribution over the width of the nip. Even with extreme thin film where while using conventional methods a bead is no longer visible as it is too small. Our measuring system "WUMSY" which we developed measures indirectly the bead size via non contact infrared temperature measurements. It shows you the bead size and it’s distribution across the whole width of the nip. The system tells you exactly which adjusting screw and how much this screw has to be turned to reduce the differences in bead sizes. This system helps you to minimise start up times of your line and to improve the product quality of your sheet or film. The best effect is achieved when using the measurement for a close loop die control to homogenise the lokal melt streams over the width of the die. This development was carried out in close co-operation with the Institut für Kunststoffverarbeitung an der RWTH Aachen, (IKV, Prof. Michaeli)
 
 

Advantageous applications for this technique:

• Sheet and film lines which run expensive resins
• Lines with close loop control for the lip or membrane adjustment of slit dies


Our WUMSY system helps you to increase the efficiency of your film or sheet production process by:

• reducing start up times of your lines · reducing change over times to produce different thickness'

=> reduce of scrap, increase of the capacity of the line

• increase of the process reliability due to a bigger processing window · possibility of implementing alarm signals for minimum and maximum allowable bead size · possibility to protocol the optimized production (bead) situation for every product

=> increase of the capacity of the line

• reduction of the thickness tolerances due to an improved knowledge of the correlation between the forces in the roll stack and the bending of the rolls · homogeneous cooling of the web across its entire width · correlation of surface defects to certain bead situations · correlation of the thermoforming behavior to certain bead situations · aid for defect analysis and for process optimization · aid to detect problems with the roll stack (for example running truth of the rolls)

=> increase of product quality

Wumsy is an initial condition to establish an automatic die control during the production of sheet or films which are running through a roll nip during the extrusion process. It:

• automatically integrates an important part of the quality control into the production process · helps to produce a product quality at a high level which is independent from the qualification of the production personnel

WUMSY is our new key to improve you economics in sheet and film extrusion.

Please do not hesitate to contact us.


Publications:
 

• N.N.: Temperature measurement system shortens sheet line adjustment time. Modern Plastic International, December 1996 
• Michaeli, W.; Groß, H.; Langkamp, U.; Schäfer, B.; Roloff, T.: Wulstmeßmethode die Technik von morgen. Zeitschrift Kunststoffe Synthetics, Heft 7/94, Seite 14 - 19 
• Groß, H.; Michaeli, W.; Langkamp, U.; Roloff, T. Wulstgrößenmessung. Zeitschrift Plastverarbeiter, 47. Jahrgang, Heft 3/96, Seite 48-51