Explain in detail the four important factors that affect printing quality of Folding Paper Boxes

Explain in detail the four important factors that affect printing quality of Folding Paper Boxes

There are many factors that affect the quality of Folding Paper Boxes, the common ones are: dot gain, printing contrast, dot deformation, overprinting, ink layer thickness, paper smoothness, printing speed, plate wear, etc. In printing production, no matter how carefully the press operator works, the above phenomenon will always occur. In order to ensure the stability of printing quality, the operator must sample and test the printed products, make judgments on the changes, and take corresponding adjustment measures.

Some main characteristic parameters that need to be measured are introduced here, and a sample sheet is measured and evaluated using a densitometer X-Rit530 and other instruments as an experimental example.

1. SolidInkDensity

Solid density refers to the density value at 100 percent dots, which is measured by a densitometer on a solid color block. Solid density can be understood as a qualitative or quantitative description of the match between printing paper and printing ink. Qualitatively speaking, if the solid color block is visually darker and brighter, and the dots observed with a magnifying glass are relatively full, it means that the color of the image in the sample is relatively saturated, which basically meets the printing requirements. On the contrary, it means that the combination of the paper and the ink is not good. Quantitatively, we can use a densitometer to measure the solid density D on an existing solid patch. There are two measurement methods: first, in the same printed sheet, select different solid color blocks in different orientations (horizontal/vertical) for measurement, and draw the result as a state curve of solid density; second, in a certain state Select continuous proofs or discontinuous sampling proofs for measurement on the printing press in , and also draw a curve to obtain the solid density state curve under the printing state. According to the drawn solid density curve, we can find the difference law between solid densities at different parts of the same sheet and the variation law of solid densities between continuous proofs or discontinuous proofs. We can adjust the printing process through such a law.

In general, in order to effectively reproduce the image tone value, we need to control the solid density of each color. For fine prints, the solid density of yellow (Y) needs to be controlled at {{0}}.85-1.15, magenta (M) The solid density should be controlled between 1.25-1.55, the cyan (C) should be controlled at 1.30-1.60, the black (BK) should be controlled between 1.40-1.80, and the deviation of the same color density should not be greater than 0.05. For general requirements, the solid density of yellow (Y) should be controlled at 0.80-1.10, magenta (M) should be controlled at 1.15-1.45, cyan (C) should be controlled at 1.25-1.55, and black should be controlled at 1.25-1.55. (BK) needs to be controlled between 1.20-1.60, and the deviation of the same color density is not more than 0.07.

It can be seen from the measurement results that as a general printed matter, except for yellow and black that meet the general printing requirements, others cannot meet the general requirements for printing quality of Folding Paper Boxes. In addition, the color difference of each color block is large, which means that the ink supply is uneven.

In the range of low field density values, field coverage is the main factor affecting the size of field density. If the solid coverage reaches saturation, the influence of the thickness of the ink layer should be prominent. As the thickness of the thinner part of the ink layer increases, the thickness of the ink layer tends to be uniform, so the solid density increases. After further reaching the high solid density value range, the smoothness of the ink surface will also affect the solid density value.

2. Dot Gain (DotGain)

Dot enlargement refers to the difference between the dot size and the dot size on the color separation sheet. In printing production, due to the influence of printing pressure, the number of screen lines, the shape of the dots, the double reflectivity of the paper to the light and other factors, the expansion of the dots is a normal existence, but it should be controlled within a certain range. Generally speaking, the dot expansion of fine printing should be controlled at 10 percent -20 percent , while the dot expansion of general Folding Paper Boxes should be controlled at 10 percent -25 percent .

From the test results, it can be seen that as the percentage of outlets increases, the percentage of outlets increases, and reaches the maximum when it reaches 70 percent , which is caused by the overlapping of outlets. And the proof basically meets the requirements of fine printing in controlling the expansion of the dots.

3. Relative contrast (PrintContrast)

Relative contrast is used to reflect the transition of levels between midtones and shadows. The calculation formula is as follows: Ds-D75Ds where Pc is the relative contrast, Ds is the solid density, and D75 is the 75 percent color block density.

Generally speaking, as the solid density of the image increases, the relative contrast of the image gradually increases. However, when the solid density increases to a certain value, the dot expansion occurs, the relative contrast begins to decline, the level decreases, and the contrast decreases.

Comparing the experimental results with the printing standard data, it can be seen that the printing requirements are basically met. In addition, it should be known that when the ink amount reaches 10μm thickness, the ink will reach its solid density. If the ink amount is increased, the solid density of the ink will increase slowly or almost no longer, but will lead to the continuous increase of the dots.

4. Overprinting rate (InkTrapping)

Overprint is used to describe the ability of an ink to adhere to the printed surface of the previous color. Generally, only red (R), green (G), and blue (B) are detected. Its calculation formula is as follows: T=Dop-D1D2 where T is the overprinting rate, Dop is the density after overprinting, D1 is the density of the first primary color, and D2 is the density of the second primary color.

The larger the value of the overprint ratio, the better the overprint effect. The quality of the overprint rate is closely related to the printing color sequence. In the actual printing production process, the quality of Folding Paper Boxes reflected by different overprinting rates will be different accordingly.

https://www.minongpackaging.com/paper-box/folding-paper-box/folding-paper-boxes-for-drug.html