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Calendering is the deforming of heated uncured rubber compounds to rubber sheets and tissues surrounded by rubber. The rubber sheets and tissues produced in one or more roll gaps will be used in rubber industry such as in tyre and belt-conveyor production.

The occuring deformation processes in the roll gap influence the dimension stability, surface finish, formation of gas entrapments and shrinkage of calendered rubber sheets. By using the power law of Ostwald and de Waele the flow behavior for isotherm systems in the roll gap can be described. Calculation of velocity and pressure distribution in roll gap permits conclusions to the calendering behavior. Together with the roll gap the affinity of rubber to gas entrapments can be verified.

With the 4-roll-F-type calender at DIK all important processing parameters as roll temperature, friction, roll gap and angular velocity can be varied. Investigations show that the maximum pressure into the roll gap is dependent on the roll temperature and the roll gap.

Using 3D-Micro-computer tomography at DIK the number, distribution and aspect ratio of gas entrapments will be detected. Especially small gas entrapments (radius >0,1 mm) which are hard to detect during production, can be located by this non-destructive testing method.