How to Monitor and Control the Color of Plastic Film Throughout Production
Blow, multilayer, and biaxially oriented film extrusion lines move quickly and should only be stopped to change the job. To ensure quality, many plastic manufacturers pull a film sample to measure in the lab, but by the time a color, haze, or transparency issue is identified most of the run is already wasted. An early warning system can help plastic manufacturers to keep color, brightness, transparency, and haze in harmony so the line can keep moving.
Challenges
Many production variables can cause color shifts throughout a run.
- Variability in raw materials, recycled material, opacity, thickness, additives, and plastic colorants concentration can cause inconsistencies.
- Machine parameters like speed and temperature can create production shifts.
- Stopping production for a quality issue or manually switching colors on the extrusion line can waste tons of plastic.
- If not monitored during a continuous extrusion, a production error can add up to a financial loss of $10,000 or more in just a couple of hours.
Solution
Monitoring color during continuous extrusion can catch color errors early so changes can be made before production is impacted. X-Rite’s inline plastic color measurement and control system includes a non-contact spectrophotometer, a custom traversing beam to reach pre-defined positions over the plastic web, and quality control software to monitor color throughout the run. It serves as an early warning system by alerting the operator of a shade change and automatically adjusting die gap, dye pumps or feeders to bring color back into tolerance. It also offers automatic start up and shade changes to further minimize operator intervention.
X-Rite solutions can span the entire process – including inspection of incoming raw materials, color matching in the laboratory, measuring the film directly on the machine, quality control and final inspection – to keep color and brightness in harmony. During production, the traversing beam enables measurement from left to middle to right and throughout the entire run.
Results
Monitoring color inline throughout production provides operators with real-time color information to avoid costly line errors and rework.
- Attain accurate light transmission and haze values for transparent products
- Achieve more stable and consistent color
- Minimize cost and waste that results from stopping the extrusion for a production issue
- Decrease operator intervention by up to 45 minutes per automatic startup
- Reduce material and energy waste during start up and color change by up to 50%
How it Works
A custom traversing beam is fit to the film or plastic production machine. This frame holds the inline spectrophotometer over the product to take measurements left side, middle, and right side. Then it moves the instrument away during a sheet break and returns to measurement position when it is time to run. Opaque films will be measured in reflectance, while transparent films will be measured in transmission to quantify color, haze, and light transmission. Measurement is most commonly set before reel up, but can be placed anywhere in the production process.
The inline spectrophotometer is connected to a computer running quality control or full closed loop color control software. The software uses color data captured by the instrument to calculate the adjustment of colorants and automatically adjust the dye pumps or feeders to achieve the target color without stopping production.
To make a shade change, the operator chooses the color from the database and the system will automatically adjust the dye pump or feeder and start the run. The QC software can also report up to eight color trends in L*a*b*, Delta E, whiteness, opacity, visual light transmission and correlated haze so operators can understand color deviation and implement process improvements on the spot.
Featured Products
ERX130 Inline Spectrophotometer
Features a large measurement spot of 90 mm (3.5”) to measure without contact and deliver a good average of the measured color on a full range of textured, finely patterned, and gloss samples.
ColorXRA 45 Inline Spectrophotometer
Measures color, whiteness and brightness inline on the finished paper and evaluates color deviation to enable corrections without stopping production. With standardized 45°/0° measurement geometry, it provides good correlation to laboratory instruments.
ERX55
The ERX55 is an inline, non-contact spectrophotometer for transmission measurement on transparent film or panes. It continuously measures color, visual light transmission, and haze on the moving production line.
ESWin Quality Control Software
A customizable software solution that integrates with inline spectrophotometers to evaluate OBAs and control color quality, evaluate trends, and correct current or emerging problems. ESWin can connect for bi-directional communication to any process control or ERP system using OPC.
ESWin Closed Loop Color Control Software
When combined with an X-Rite inline color measurement instrument, ESWin CLCC manages color quality on continuous process manufacturing lines, displays results, and runs automatic inline closed-loop color control on plastics machinery.
Custom Traversing Beam
A customized aluminum frame that can be built to fit any production line and mount the inline spectrophotometer above the web for continuous non-contact measurements from left to center to right.
Achieve Color Success
An inline solution from X-Rite can help plastic film and sheet manufacturers ensure color harmony from raw material inspection and laboratory color matching through production quality control and final inspection. Learn more at https://www.xrite.com/categories/inline-measurement.
