Ink printing is a process with high technical requirements, involving material selection, equipment operation and environmental control. The following are the key points that should be paid attention to in the process of ink printing to ensure the printing quality and efficiency:
1. Ink selection and preparation
Matching printing materials: different materials (such as paper, plastic, metal, etc.) need to choose the corresponding ink type. For example, plastic printing usually requires UV ink or solvent-based ink with strong adhesion.
Viscosity control: too high ink viscosity may lead to uneven transfer, and too low ink viscosity is easy to smudge. The diluent ratio should be adjusted according to the printing speed and ambient temperature.
Spot color blending: blending strictly according to Pantone color card or customer requirements, and recording the formula for subsequent batch use.
2. Preparation before printing
Printing plate inspection: ensure that printing plates (such as offset PS plate and flexo resin plate) are free from abrasion and dirt, and the dots are clear. New plates need to be tested for pressure uniformity.
Equipment calibration: adjust the pressure of ink roller and water roller of printing machine to avoid dirty or paste plate caused by ink imbalance. Multicolor printing needs to register each color group.
Environmental control: the change of temperature and humidity will affect the drying speed of ink and the expansion rate of paper. It is recommended to keep the workshop temperature at 20-25℃ and humidity at 50%-60%.
3. Printing process control
Ink quantity adjustment: Monitor the ink key opening in real time according to the graphic density to avoid the ink layer being too thick (easy to rub dirty) or too thin (color unsaturated).
Drying management: When using infrared drying or UV curing, it is necessary to match the ink characteristics. Excessive drying may lead to embrittlement of paper, while insufficient drying may lead to sticky dirt.
Overprinting accuracy: the overprinter marks are randomly checked, especially in multi-color printing. If any deviation is found, the roller or tension system should be adjusted in time.
4. Handling of common problems
Flying ink: It may be caused by too low ink viscosity or too high printing speed, so it is necessary to add thickener or reduce the speed.
Dot blur: check whether the printing plate pressure is too high or whether the blanket is aging.
Color difference: check the color difference regularly with a spectrometer (ΔE≤3 is qualified), and clean the ink roller to prevent cross-color.
5. Safety and environmental protection
Ventilation protection: solvent-based ink should be used in a well-ventilated environment, and operators should wear gas masks.
Waste disposal: waste ink and cleaning agent should be recycled separately to avoid environmental pollution. UV ink is solid waste after curing and can be treated centrally.
6. Post-press maintenance
Equipment cleaning: Clean the ink tank and ink roller in time after shutdown to prevent ink from curing and blocking.
Maintenance of finished products: printed matter should be fully dried and stacked to avoid page sticking caused by heavy pressure, especially in large-scale field printing.
Through the above measures, the consistency of printed matter can be effectively improved, the rejection rate can be reduced, and the service life of equipment can be prolonged. In actual production, it is necessary to flexibly adjust the parameters in combination with specific processes (such as offset printing, gravure printing, screen printing, etc.).
