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| The plant operator can get an idea of the melt condition by consulting the control panel |
For many plastic extrusion companies, raw material costs are by far the largest cost factor. The raw material costs for a pipe or film extrusion manufacturer for example often exceed 70 % of the total production costs. Accordingly, there is great pressure to reduce raw material expenses. An obvious approach is to process reasonably priced polymer granules and recyclate. But how to ensure that the products manufactured in this way are of sufficiently good quality?
The Promix Visco-P viscosity measurement system offers an interesting solution to solve this challenge. It provides control of the raw material composition, thereby optimizing raw material quality.
In many plastics extrusion processes, the melt viscosity is a reliable indicator for the quality of the products manufactured. A decreasing melt viscosity often indicates a decrease in polymer chain length, which is often associated with decreasing mechanical properties such as tensile strength or notch impact resistance. On the other hand, raw materials with a lower viscosity such as recycled polymer are usually less costly. This is exactly where the Promix-Visco-P comes in. It supports the idea of continuously mixing the cost-effective, low-viscosity raw materials with the more expensive, higher-viscosity raw materials in the correct ratio. In order to ensure a stable quality level, the viscosity of the complete melt flow in the Promix Visco-P is continuously measured and the composition of the mixture can be adjusted if necessary. The adjustments can be made manually or can be linked to Visco-P by means of a corresponding control loop, which will ensure the dosing systems automatically add the correct amounts of raw material. With Promix Visco-P, the product quality can be continuously monitored during production. This helps to avoid product batches with poor quality and at the same time optimizes raw material costs. Promix Visco-P can be installed in both, existing as well as new extrusion lines. A nice side effect is that the mixing module used to measure the viscosity also improves the melt homogeneity, which is reflected in very narrow thickness tolerances and an excellent surface quality.
