Inline process monitoring opens the door for a lot advantages and benefits:
- In-situ application, non-destructive, no sampling, no material loss
- Real-time information about process stability & quality
- Impact of speed changes on the quality of the extrusion
- Determination of optimal extruder screw configuration
- Innovative residence time measurement and analysis
- Controlled color changes: start phase, end of run
- Detection of pulsing pumps/bridge building
- Avoid off-specification batches & waste production
- Detection of dosage elevations
- Optimized recipe formulation & processes design
- Comprehensive quality - Documentation of the quality of the delivered product
- Reduced costs results in higher ROI
Extrusion is a very complex process subject to influence by various factors.
Such factors can be process parameters e.g. temperature, pressure, production speed, etc. the extruder and its components i.e. pumps, feeders, blenders, combination of the screws, cooling, vacuum etc. In addition, raw material can influence the result, reflecting different lots, ratio of mixture etc. All these factors, either singly or in combination result in modification to the color of the produced material during the extrusion process.
Color measurement is a well-accepted technology to check the quality of the color values in the production process
. Usually these measurements are performed off-line. The time between sampling and obtaining the results from the laboratory can take several hours. A significant disadvantage is that only a single measurement is generated in this time period and the quality of the color during before and after the sampling point is unknown
. With the inline process monitoring by measuring the color taking place directly in the melt is not only complete documentation possible, but when color variations occur, immediate intervention can take place. With our method are the measured results available in real time.
Color values not only
are an indicator for product quality but also useful as an excellent insight for process monitoring in the extrusion stage
. All parameters in the production process (temperature, pressure, production speed, feeders, pumps etc.) have an impact directly on the color values. It is now possible to make measurements directly in the melt
without the need for sampling. Immediate adjustments of the process parameters are therefore possible through immediate off-specification detection.
Detected information is the spectra in the molten polymer during the process. Calculated, displayed in real-time and stored data for the analysis are: L*, a*, b*, C*, h, dE*, YI, WI, selected spectral range etc.
The “InSpectro X” technology deploys a probe directly in the extruder. The Reflection Polymer Melt Probe (RPMP) is installed on the exit of the extruder by using ½”-20 UNF thread (typ. Dynisco®).
It is screwed into position on the exit of the extruder. The RPMP consists of the threaded sleeve and fiber optics. A sapphire on the tip of the probe is the observation window and is very well suited to the harsh conditions in the extruder (temperature, pressure, and friction through flowing material). The melt stream must completely cover the sapphire surface. The self-cleaning function
of the sapphire is ensured by the shear force of the material flow. Ideal installation is directly into the melt stream at the die-plate, in an adapter or flange. Measurements are performed on opaque as well on transparent materials.
The UV-VIS spectrophotometer “InSpectro X” is integrated in a NEMA4 box (equal to IP55) with a panel PC and touchscreen. The appropriate spectral range is 220 through 820 nm (resolution 1 nm)
. “InSpectro X” comes in a stainless steel box, designed and equipped specifically for this application in the production environment where the ambient conditions can be dusty, vary in temperature, subject to vibration etc. The box also contains a thermoelectric cooling and heating device to eliminate the influences from ambient temperature by keeping the temperature inside the box at a constant level.