Published: TONGCHUANG MACHINE
When running a nylon evoh film extruder machine, even experienced operators will occasionally encounter abnormalities or malfunctions. The combination of nylon (polyamide) and EVOH (ethylene vinyl alcohol) creates exceptional gas barrier properties, but these materials are also sensitive to moisture, temperature swings, and shear degradation. This article identifies common problems and provides practical solutions to keep your line running efficiently.
Problem one: gels or fisheyes in the finished film. On a
nylon evoh film extruder machine, gels typically appear as small, hard, translucent particles embedded in the film. They weaken the barrier and create unsightly defects. The most frequent cause is degraded polymer. Nylon and EVOH both degrade rapidly if melt temperature exceeds their recommended range. For nylon, the upper limit is around 240 to 250 degrees Celsius; for EVOH, it is 210 to 220 degrees Celsius. Solution: Check all barrel and die thermocouples for accuracy. Reduce temperatures in 5-degree increments until the gels diminish. Additionally, verify that the screw design does not create localized hotspots. If the problem persists, pull the screw and inspect for carbonized residue on the flights, then clean thoroughly.
Problem two: bubbles or splay marks. These appear as small voids or silver streaks. The primary culprit is moisture. Both nylon and EVOH are hygroscopic; they absorb atmospheric water rapidly. Even 0.05 percent moisture content can cause hydrolysis, releasing gas bubbles during extrusion. Solution: Install or verify the performance of your desiccant dryer. For a nylon evoh film extruder machine, nylon typically needs drying to below 0.08 percent moisture, while EVOH requires below 0.03 percent. Dry at 80 to 90 degrees Celsius for four to six hours for EVOH, and at 80 degrees Celsius for four hours for nylon. Never mix drying hoppers. Use a dew point meter to confirm the dryer delivers air at minus 40 degrees Celsius or lower. Also check hopper seals for leaks that let humid room air enter.
Problem three: poor interlayer adhesion. Coextruded films depend on tie layers to bond nylon and EVOH to polyolefin skins. If the film delaminates during handling or sealing, the barrier is compromised. Possible causes include inadequate tie resin temperature, insufficient residence time in the die, or contamination. Solution: First, confirm that the tie layer extruder is set to the temperature recommended by the resin supplier, typically between 190 and 220 degrees Celsius. Second, increase the thickness of the tie layer slightly; a very thin tie layer may fail to cover the interface completely. Third, check for oxidized surfaces. Nylon and EVOH can form a skin if exposed to hot air at the die exit. Adjust the air ring or cooling settings to minimize exposure. Finally, run a peel test on samples taken from different positions across the film width to identify localized adhesion loss, which may indicate die lip damage.
Problem four: inconsistent gauge or thickness variation. A nylon evoh film extruder machine is more sensitive to die temperature uniformity than a mono-layer line. If the die is not perfectly level or if heating zones fluctuate, the barrier layer may become thinner on one side. Solution: Use a portable infrared thermometer to scan the die lip surface; all points should be within plus or minus 1 degree Celsius of setpoint. Adjust band heaters or replace failed cartridges. Also verify that the air ring is concentric and not partially blocked by carbon buildup. An inline thickness gauge with automatic die bolt adjustment is highly recommended for nylon/EVOH production.
Problem five: excessive screw and barrel wear. Nylon can be abrasive, especially if reinforced with glass fibers, and EVOH has low thermal stability that leaves carbon deposits. Over time, this increases melt temperature due to friction and reduces output. Solution: Monitor the motor amperage and melt pressure. If pressure drops while amperage rises, screw flight wear is likely. Plan to rebuild or replace the screw after 6,000 to 10,000 hours of operation, depending on materials processed. Use bimetallic barrels and screws with hardfaced flights to extend life.
Problem six: die drool or plate-out. Brown or black deposits accumulate on the die lip, then break off into the film. EVOH is notorious for this, especially when processed with certain slip additives. Solution: Reduce the melt temperature of the EVOH layer by 5 to 10 degrees if seal strength allows. Add a small amount of processing aid or fluoropolymer additive. Increase purge frequency: every four hours, inject a purging compound designed for high-temperature engineering resins. Clean the die lip with a soft brass scraper during production, but be extremely careful not to scratch the polished surface.
In conclusion, most abnormalities on a nylon evoh film extruder machine trace back to moisture, temperature, or wear. Implement rigorous drying protocols, verify thermal accuracy daily, and schedule regular screw inspections. When a problem appears, use the systematic approach above: identify the symptom, check the most likely cause, apply the targeted solution, and document the result. With proper care, your nylon EVOH line will deliver high-barrier film reliably.
What quality certifications are required for blown film extruder manufacturersf quality are difficult to verify.Beyond general quality management, safety certifications are legally mandatory for selling machinery in many regions. In the European Union, the CE marking is compulsory. To affix the CE mark to a blown film extruder, the manufacturer must ensure the machine complies with all applicable EU health, safety, and environmental protection legislation, primarily the Mac...
Analysis of the reasons for the widespread use of seven co extrusion downward extruder machinexygen or moisture, layers for structural strength, layers for sealing, and layers for aesthetic appeal or printability. This multi-functionality, achieved in one pass through the seven co extrusion downward extruder machine, eliminates the need for multiple production steps or post-production laminating, saving significant time and cost. It enables the creation of high-performance packaging films,...
What quality certifications are required for high speed screen changer manufacturerspment based on its hazard level, and most high speed screen changer units fall under categories requiring involvement of a Notified Body. This results in the CE marking, indicating conformity with health, safety, and environmental protection standards. Similarly, for the North American market, adherence to the ASME Boiler and Pressure Vessel Code (BPVC), specifically Section VIII for pressure vess...
Analysis of the reasons for the widespread use of 5 layer film blowing machineing machine also excels in producing films with superior mechanical properties. The combination of layers allows for balanced tensile strength, puncture resistance, and tear propagation resistance, making the films suitable for heavy-duty applications like industrial liners, construction membranes, or geotextiles. Additionally, the machine's precise control over layer thickness and distributio...
