Complete Operational Process Analysis of Label Printing Machines
December 10, 2025
I. Pre-Printing Preparation Stage
Pre-printing preparation for label printing is the foundation of ensuring printing quality, requiring the calibration of materials, equipment, and parameters. Firstly, material preprocessing: Select appropriate substrates (such as coated paper, PP synthetic paper, self-adhesive paper, etc.) according to the label's application. Check the flatness of the substrate surface and remove dust or oil stains to avoid missing prints and plate sticking during printing. For self-adhesive substrates, confirm whether the release force of the backing paper matches the printing speed to prevent label adhesion after die-cutting. Secondly, equipment inspection and commissioning: After starting the printing machine, check the cleanliness of core components such as rollers, doctor blades, and anilox rollers to ensure no residual ink or debris. Calibrate the machine's tension control system and adjust the unwinding and rewinding tension according to the substrate thickness to avoid stretching or wrinkling. Meanwhile, adjust the printing pressure to ensure uniform contact between the printing plate and the substrate—excessive pressure may damage the substrate, while insufficient pressure can cause blurred text. Finally, parameter setting: Based on the precision requirements of the printed pattern, set the printing speed (usually 30-150m/min) and ink viscosity (water-based ink viscosity is generally controlled at 15-25s). Import the label design file through the computer terminal, accurately position the pattern's location and size, and lock the parameters before test printing.
II. Core Printing Operation Stage
The core printing process varies slightly by machine type (e.g., flexographic printing machines, letterpress printing machines, digital printing machines), but the core logic is consistent. Taking the widely used flexographic printing machine as an example: Step 1, ink transfer: Ink is delivered to the anilox roller by an ink pump. The doctor blade scrapes off excess ink, leaving only a fixed amount of ink in the anilox cells to ensure uniform ink transfer. Step 2, pattern transfer: The printing plate cylinder closely adheres to the anilox roller, transferring the ink in the cells to the image-text areas of the printing plate. Subsequently, the printing plate cylinder contacts the substrate under pressure, completely transferring the pattern to the substrate surface. Step 3, instant drying: The printed labels immediately enter a drying system (hot air drying, UV drying, etc.). Water-based inks use hot air drying (temperature 50-70℃), while UV inks are cured by UV lamp irradiation. The drying speed must match the printing speed to prevent ink adhesion or discoloration. During printing, operators need to monitor the printing effect in real-time, adjust the substrate position through the machine's deviation correction system to ensure pattern registration accuracy (registration error ≤ 0.1mm), and check for uniform ink color, missing prints, smudges, and other defects.
III. Post-Processing and Finished Product Handling
After printing, labels undergo multiple post-processing steps to become qualified finished products. Firstly, die-cutting process: Install the corresponding die-cutting plate according to the final label shape (circular, square, special-shaped, etc.). Adjust the die-cutting pressure and position to ensure neat, burr-free edges and avoid damaging the backing paper. After die-cutting, the waste removal device clears excess scrap, retaining the formed labels. Secondly, laminating/varnishing (optional): For labels requiring enhanced wear resistance and water resistance, laminating or varnishing is performed. A transparent film or varnish is evenly applied to the label surface, and a pressing device ensures tight adhesion between the film and the label. Processed labels have a smooth surface and good gloss. Finally, rewinding and inspection: Neatly rewind the processed labels with stable tension to avoid wrinkling. Conduct finished product inspection by sampling to check dimensional accuracy, printing clarity, die-cutting quality, and other indicators. Reject unqualified products, while qualified finished products are packaged, warehoused, and prepared for delivery.
