Proofing in prepress plate making process is a very important process. Proofing can check in front of the process of production quality, and at the same time, the proof is to pull behind a large number of printing color tracking standard. Therefore, proofing plays a transitional role, is the process the quality management and control the important one link in.
Affect the quality of the samples there are many factors, such as: makeup, plate burning, development, ink, clean water, field density, network increases, playing a prototype for the maintenance and maintenance, environmental temperature and humidity, etc. These factors no matter which has the problem, can the final proofing results have a significant impact. Therefore, only the standardization, and data management and operation ability in the drafting of a node is made in the process of copying and reduction, and meet the requirements for large quantities of printing to provide qualified after everything zhang. Below we will put in the drafting process of how the main factors for effective control method and related data and readers discussed one by one.
A, makeup, printing and development
The samples of pieces and printing of spell big edition are quite different. Printed spell big version must be according to the binding to the folding order to spell, and part of the film's reticle and Angle line will be cut off, therefore, the idea of personnel can only according to the edge of the image on the film or lines and colors more easily and contend somewhere else to align and alignment. And the samples of pieces will not need to consider the problem of folding hand, the full width of the film and Angle line can be preserved. When the pieces as long as all kinds of film reticle and Angle line alignment can. Generally speaking, proofing color sequence determines the color sequence of pieces. Because it can improve the work efficiency. The first day in spelling, film should put level, not tilt, four corners with transparent tape is good. Three other color version is based on the alignment respectively. Alignment of the standard for the eyes to see the film and the reticle and Angle line have migration phenomenon.
To print, development of control is through the UGRA control bar to achieve. UGRA article control there are five function section, each has its different functions. As shown in figure:
The first Ⅰ section: used to control the development of the printing plate, also can evaluate plate exposure. Qualified for from the third stage began to appear classification, the ninth stage began to cause not clear classification.
The first Ⅱ section: micron coil is used to control the time of exposure. Qualified for the 12 μ m place began to clear resolution micron coil.
The first Ⅲ section: network section points to 100% 10% network field 10 block, which is used to check the exposure and development, also used as a printing characteristic curve measurement standard. Qualified for 2% outlets appear, 3% network clear.
The first Ⅳ section: along the different angles of the fine line, you can check whether network deformation and double.
The first Ⅴ section: fine network section points Yang diagram 0.5% to 5% and female figure 95% to 99.5%, which is used to check the proofing process node is reduced.
Although through the UGRA control bars can be compared to exposure and development accurately control, but in some slight place still need operators to adjust experience, in order to make the network copy and reduction to achieve the best. For example, in view of the different thickness of the plate for extraction time adjustment, developing machine temperature and speed matching adjustment and printing machine glass cleaning and maintenance, etc.
Second, the drafting
Test press and press has a big difference. Press the "circle pressure circle" of the printing way, and play prototype, the use of the "round flatten" printing mode. In addition, printer ink in, alignment automation level is very high. Test press, it is mostly by the operating personnel according to the personal experience adjustment to ink quantity, and all kinds of version of the alignment is through the hands. Although the proofing process, the operator must also rely on density meter constantly measurement field density and 80% in network density and outlets to adjust to increase the quantity of ink and ink balance, but in the process of ink or must with ink shovel the ink shovel to playing prototype of the roller. Therefore, the quality of the samples and the level of operators is closely related.
Field density value is control network copy and restore the most important technical parameters. Different companies have their own different technical indicators and the error range. The technical indicators are companies according to their own specific conditions and decide. General all kinds of version of the field density for Y: 1.30, M: 1.45, C: 1.50, K: 1.80. As for the error range, European standard is 0.07 mm. It is said that a domestic company in the range of error control within 0.05 mm.
And printing, proofing to ink balance control is also very important. The principle of printing essentially is the principle of oil and water don't mix: PS version on exposure formation image network part oil-wet not hydrophilic, not exposure the blank portion of a hydrophilic not oil wet. Therefore, to maintain good ink balance is very important. Water clean too little, can cause dry edition, reflected in the prospectus is appear dark tone level and level; Water clean too much, can lead to network deformation, printed sheet on the site there will be "hollow point". So, how much should wipe water how to control? Generally speaking, the water clean as little as possible. Mastery of the scale is when the water after the roll on the version to see if the presence of water.
Education version fluid technology parameters in the drafting of the quality control is often neglected factor. Education version fluid technology parameters mainly for the conductivity and pH value. Their standard respectively is: conductivity for 800 ~ 1
200, pH value is 4.8 ~ 5.2.
Proofing quality control also involves the adjustment of the kumite prototype. The content of the adjustment basically has the following kinds:
(1) rubber cylinder pressure is + - 0.03 mm (every rotating 120 ° measuring time, averaging), namely rubber cloth thickness + gasket thickness = (2.286 + / - 0.03 mm.
(2) version of the table pressure (including the thickness of the PS version) for + 0.12 mm ~ + 0.15 mm, or PS version of the surface is higher than the height of the guide.
(3) paper table pressure (including the thickness of paper) for + 0.15 mm ~ + 0.18 mm, namely paper surface is higher than the height of the guide.
(4) activities on both sides of the frame
(5) distributing system: inking roller in the version of the ink bar width and paper on the pressure ink bar width should be uniform.
Three, and environmental factors
Environmental factors influence the quality of the samples are mainly temperature and relative humidity. The temperature is too high or too low, can make the brush to PS version of the water evaporates more too fast or too slow, thus damage ink balance. Environment relative humidity too big or too small will also destroy the ink balance, and even produce ink emulsification phenomenon leads to the production of hollow outlets. In addition, more serious is the temperature and humidity instability can make paper deformation, leading to the alignment precision decline. Therefore, in the proofing workshop keep constant temperature and humidity is very important. Generally speaking, the environment temperature should be 22 ℃ ~ 23 ℃, relative humidity 50% best.
Four, concluding remarks
Improve the quality of samples need to control the element has a lot of, this is just a simple analysis and introduces some main control method and empirical data, there are many subtle factors not to list. In the drafting process, often a small mistake can lead to the production of waste. Therefore, should according to the company or the department's specific conditions to develop a set of complete, practical and feasible management system and operating procedures, standardization, digital proofing to orbit. Only in this way, can we make the quality of the samples in a high level of basis to stability. (Gold Printing Group)