Gravure printing proofing method and equipment

Proofing is a very important part of the gravure printing process, and it is the main basis for determining the contract between the plate making company, the printing company and the customer. However, due to the wide variety of substrates for gravure printing, it could be films, aluminum foils, composites, or a variety of paper or cardboard. Therefore, the gravure proofing must have high flexibility, and have the corresponding equipment and process support.

Gravure proofs can be analog or digital. Simulation proofing includes Gravure Press Proof, Blueline or Ozachromo Proof, Overlay Proof, Single Sheet Proof, Offset Press Proof. And so on; digital proofs are mainly Soft Proof and Direct Digital Proof.

Here, the emphasis is on direct digital proofing and gravure proofer proofing. Direct Digital Proofing, also known as Direct Digital Color Proof (DDCP), uses inkjet or electronic imaging proofers that use digital technology to obtain high-resolution halftone proofs directly on thermal transfer materials, eliminating the need to use them. Intermediate film steps. This proofing process is fast, subtle and distinct, but has a limited range of color rendering.

Direct digital proofing has the characteristics of high production efficiency, reliability, convenience, etc. Therefore, some manufacturers have taken the lead in abandoning the gravure proofer for proofing, and have completely adopted digital proofing without film. Undoubtedly, direct digital proofing is the trend of future development.

At present, the most used proofing method is the gravure proofer proofing method. The gravure production technique requires that the proofs printed by the gravure proofer should be printed by the printing company and the results are basically the same. Therefore, the construction of the gravure proof printer is not significantly different from the gravure printing machine. It is made by simulating the principle of gravure printing machine, and the ink is transferred to the substrate to form a clear pattern through the pressing action between the impression cylinder and the gravure plate roller.

The new gravure proofer has been continuously exploring and simulating the actual printing process (imprinting form, ink, printing materials, etc.) and has taken a series of improvement measures. At present, the domestic GRAV-PROOF Gravure Proofer and the British JM Headford Gravure Proofer are the most commonly used in China.

The main components of the gravure proofer are the impression cylinder, registration device, plate cylinder and transmission components. During proofing, the impression cylinder presses the substrate on the gravure surface by the pressure. When separating, the substrate absorbs the ink in the gravure network and forms an image. The quality of image transfer depends to a large extent on the rubber on the outermost layer of the impression cylinder. The magnitude of the rubber strength determines the amount of pressure transferred to the plate cylinder, which in turn determines how much ink is absorbed on the substrate.

The register device also plays an important role in the gravure proofer. First, the gravure proofer registration device needs to have good registration accuracy; secondly, the registering device is required to have great flexibility and can meet the requirements for different sizes of printing plates, different substrates, and different inks.

The British gravure proofer has the largest surface width of the plate cylinder relative to Japan's GRAVO-PROOF. The circumference of the impression cylinder can reach 4.5m, so the British gravure proofer is more suitable for printing large format products. In addition, an auxiliary electrostatic ink-absorbing device is attached to the UK. In the past, some surface-printed substrates were difficult to handle, making it harder to print subtle layers. With this device, this problem can be overcome and the ink can be transferred smoothly. The British machine has an independent register in terms of registering and has good flexibility.

The advantage of the GRAVO-PROOF machine is its small size, easy operation and high work efficiency. In terms of registration, the GRAVO-PROOF registration device is fixed.

There is also an important factor in gravure proofing that needs attention. This is ink. The level of ink viscosity is completely artificially adjusted, and the human influence factor is correspondingly large. Different ink dilution, gravure proofing effect is also different.

In a word, gravure proofing is a very complicated process. Different substrates must adjust relevant parameters in time according to their printing characteristics so as to produce perfect gravure proofs.