Definition
A laboratory gravure proofing machine is a small piece of experimental equipment used to simulate gravure printing processes. It is mainly used for proofing and testing inks, substrate materials and printing process parameters in a laboratory environment to evaluate the gravure printing effect and provide data reference for actual production. This equipment has important application value in the R&D and quality control links of packaging, decoration materials and other industries.
Principle
The working principle of a laboratory gravure proofing machine is based on the basic mechanism of gravure printing. Its core processes include: engraving or etching to form plate rollers with recessed graphics, which are used to store ink; During operation, the ink scraper scrapes off the excess ink on the surface of the printing plate and retains the ink in the depression. Subsequently, under the action of pressure, the printing plate is in contact with the substrate material, and the ink in the depression is transferred to the substrate material through capillary action and pressure transfer to form a graphic text. The amount of ink transfer can be approximated by the formula V ≈ A × d indicated, among them V To transfer the volume of ink,A is the area of the outlets,d It is the depth of the gravure mesh hole. This process simulates the ink transfer and curing behavior of actual gravure printing.
Measurement and evaluation methods
When testing with a laboratory gravure proofer, it often involves the measurement of several performance indicators. Color measurement can be measured by a spectrophotometer to determine the chromaticity value of a sampled sample, such as CIE Lab coordinates, to assess chromatic aberration. Ink adhesion is often evaluated qualitatively or semi-quantitatively by scribing or tape peeling. Print uniformity can be assessed by measuring the ink layer density in different areas with a density meter and calculating density deviations. In addition, subsequent tests such as wear resistance and solvent resistance can also be carried out on the proofing sample, and the specific method needs to refer to relevant industry standards, such as ISO 2834 and other standards when it comes to packaging and printing.
Influencing factors
The proofing effect is affected by a variety of factors. In terms of process parameters, the printing pressure and pressure settings between the plate and the imprint cylinder directly affect the integrity and uniformity of ink transfer. The angle, pressure, and wear state of the squeegee determine the cleanliness of non-graphic areas on the plate surface. Environmental conditions such as laboratory temperature and humidity can affect the viscosity and drying speed of inks. In terms of material properties, the surface energy, smoothness and absorbency of the substrate material, as well as the viscosity, pigment dispersion and drying properties of the ink are all key factors. The accuracy of the equipment itself, such as the concentricity of the drum and the transmission stability, can also affect the repeatability of the proofing results.
Applications
Laboratory gravure proofing machines are mainly used in industry R&D and quality control links that require gravure printing technology. In the flexible packaging industry, it is used to test the printability and final effect of inks on laminated films (such as BOPP and PET). In the field of decorative materials, it can be used to preview the printing effect of materials such as wood grain paper and metal foil. In addition, this equipment can also provide effective experimental methods in the development of inks and processes in the fields of anti-counterfeiting printing and special paper printing. Its core value is to complete process feasibility verification and material match testing before mass production at a lower cost and with a short cycle time.
Selection considerations
When choosing a laboratory gravure proofing machine, it is necessary to comprehensively consider a number of technical parameters and actual needs. The equipment should be compatible with the width and thickness range of the substrate material that covers the sample to be tested. The maximum printing line speed should meet the requirements of simulating actual production conditions. The adjustment accuracy and stability of the ink scraper and pressure system are the basis for ensuring the repeatability of experimental results. Whether the equipment has a drying unit, as well as the drying method and temperature control range, need to match the type of ink used. Safety protection designs, such as scraper guards and emergency braking, also need to be taken into account. It is recommended that users refer to the requirements of relevant industry standards for equipment functions according to the main test items, and conduct a comprehensive evaluation based on the actual sample size and process window.