Solventless laminating machines is an indispensable equipment in modern packaging industry. It has been widely recognized for its high efficiency and environmental protection. However, during actual operation, mechanical components, laminating processes and electrical control system may malfunction, affecting production efficiency and product quality. In this paper, the common fault types of solvent free composite machine are reviewed systematically, and the causes and solutions of the faults are analyzed according to the actual cases.
The coating system is the core component of solvent free composite machine, and its stability directly influences coating quality. Common glitches include:
- Inadequate pressure or mechanical brake failure of the conveyor roller: leading to uneven coating thickness or even leakage of coating.
- Poor finish, spotting, deformation or cleaning of coated roller surface: foreign objects or damage to roller surface can lead to coating defects such as knife lines and stripes. For example, one company found residual adhesive on the surface of a transfer roller, resulting in longitudinal knife lines on the coating layer. Replacement rollers eliminated this problem.
- The gap between metering roller and transfer roller is not uniform: too large or too small a gap can lead to a breakage in the adhesive line or coating fluctuations. Periodically calibrate the gap between the rollers.
The quality of winding directly affects the appearance and subsequent processing of the finished product. Common problems include:
- Wrap tension control is inadequate: too small a taper can lead to compression deformation of the outer ring material, or even to ``bulge ''.
- Pressure roller runout or paper core deformation: the pressure roller surface is not uniform or excessive paper core ovality over the high will lead to wrinkling when winding. On a production line, the ellipse causes localized wrinkling of PE membrane winding. Replace the qualified paper core to restore the film to normal.
- Poor film alignment: Unbalanced tension or contaminated guide rollers may result in roll movement and uneven cross sections. Check roller cleanliness and adjust tension parameters.
- Laminated steel roller temperature uneven or surface damage: too low temperature can lead to incomplete curing of the adhesive, resulting in white spots, bubbles and other defects. One company, for example, has dense white spots on the back of a laminated roller due to a temperature of only 35℃. After turning the temperature up to 50 degrees Celsius, the problem disappeared.
- Failure to adjust the deflection flattening roller: Insufficient flattening roller pressure or angle deviation can lead to uneven tension on the substrate, causing misalignment or wrinkling in the laminated layers.
The curing process directly affects the peel strength of the coating. Common problems include:
Mixing is not uniform or the ratio of two-component adhesives is not correct: A low NCO component can lead to insufficient crosslinking density and reduced peel strength. Due to the decrease of NCO composition and insufficient curing time, the peel strength between layers after curing is not up to the required standard. Adjust the bonding ratio to extend the curing time.
Insufficient curing temperature/time: Low temperature or short curing times can inhibit adhesive reaction. 2. Appropriate process parameters must be determined according to the type of
Appearance defects of laminated films will reduce the value of the product. Common types include:
- White spots/bubbles: Bubbles can be caused by inadequate application of adhesive, low substrate surface tension or high workshop humidity (e.g. >70% humidity). For NY/PE structural orders, dense bubbles are created after lamination due to 85%% humidity in 85 workshop and low adhesion applications. This involves humidity control and increasing the amount of adhesive used.
- Imbalanced tension matching or substrate relaxation can lead to sliding between layers, creating tunnel-like cavities. This requires optimization of tension control system.
- Ink-Adhesive Reaction Solvent in some inks will react with the adhesive, leading to a decrease in the blending or whiteness. Pre-compatibility testing is crucial.
- Excessive Aluminum Transfer: too fast curing speed or poor adhesive compatibility can lead to aluminum layer shedding. In one boiling water test, two adhesive samples broke away from the aluminum coating because of the high curing temperature, while a third sample remained stable after several batches, indicating the need for strict control of process conditions.
Stirring accuracy directly affects lamination quality. Common problems include:
Static mixer blockage or automatic proportioning pump inaccuracy: Uneven mixing will lead to a decrease in adhesive performance. A sensor failure in one of the company's mixers resulted in a 30% underproduction production of OH components and reduced peel strength after lamination. Sensors require to be regularly calibrated and mixed tubes replaced.
- Failures in the laminating roller heating module or temperature sensor error: Sensor errors can lead to actual temperatures below set values, resulting in incomplete curing. On one production line, the steel roller temperature sensor error of 10℃, resulting in an actual temperature of only 45℃ (set at 55℃). After adjustment, the product yield increased. Tension control failure
tension system critical for winding mass. Common problems include:
- Calibration Tension sensor signal interference or PID parameter misalignment: Parameter errors can lead to overstretching or relaxation of the film. Incorrect PID parameter settings can cause film to stretch and longitudinal wrinkles during winding. This requires recalibration and elimination of jamming sources.