7. Layer thickness measurements

The quest for higher performance has led to greater sophistication of coextrusion boxes, which in turn requires highly skilled operators to fine-tune them. The innovation of layer multipliers also stems from this trend. Optimizing settings on a multi-channel die also requires a great deal of skill.

But that's not enough: operators still need to have precise, real-time information on layer thicknesses.

As a result, there have been major developments in the field of continuous layer measurement. These measurements are carried out using infrared (IR) gauges. IR measurement technology is based on the principle described in figure 34 : for each polymer, there is a characteristic wavelength that corresponds to an absorption peak...