Don't worry if printed paper wrinkles, there are solutions!
Our Northren Type 05 printing press, due to its long years of use, often causes paper wrinkling during printing, seriously affecting print quality. Drawing on years of equipment operation experience and understanding of the machine, the author made adjustments in several areas, which significantly reduced paper wrinkling and greatly improved print quality and production efficiency. The following are the adjustment methods shared for the benefit of industry peers. Strict Control of Workshop Temperature and HumidityUnder normal circumstances, paper needs to be stored in the paper warehouse for a period of time after entering the factory. Three to four days before printing, the paper should be placed in the workshop, with strict control of temperature and humidity. The temperature should be maintained at 20–25°C, and the humidity should be kept at 50%–60%. To achieve this, our unit improved the workshop's enclosure by constructing partition walls and ceiling structures, used high-power air conditioning to regulate temperature, and adjusted humidity in dry seasons by sprinkling water in the workshop.Cut Paper Concurrently with PrintingPaper wrinkling in our unit mostly occurs with whiteboard paper, coated paper, and some lighter-weight papers. The reason is that the moisture content in these papers is uneven during printing, causing wrinkles along the edges and affecting print registration or paper alignment, delaying production. To minimize this issue, our unit adopts the practice of cutting paper as it is printed rather than in advance, preventing edge tension caused by airflow. If the paper has already developed edge tension, tapping the edges of the paper can reduce the degree of wrinkling.Adjust the Feed Belts and Pressure RollersSince the paper moves forward under the action of the feed belts and pressure rollers, the tension of these components affects the flatness of the paper. The paper must be flat when entering the oscillating device to minimize wrinkling. Therefore, proper adjustment of the feed belts and pressure rollers is essential.Adjust Oscillator PadThe oscillator pads may become uneven due to wear. When the oscillator teeth grip the paper, this can cause localized unevenness in the paper. Once the paper is delivered to the impression cylinder, the uneven areas under the rubber roller's pressure are prone to spot wrinkles. Therefore, machine operators must regularly check whether the oscillator pads are flat.Adjust the Impression Cylinder TeethFor older presses, the impression cylinder teeth may grip paper unevenly, causing irregular wrinkles at the trailing edge under pressure. To solve this, replace defective teeth on the impression cylinder and adjust the tension to ensure uniformity.Adjust Printing PressureDuring operation, if paper wrinkling occurs, printing pressure should be decreased as much as possible to reduce the degree of paper wrinkling.