Part I Glossary
High energy surface - Surface with high free energy
Grey scale - The ratio of the minimum density of area that should reject ink to the maximum density of area that should attract ink.
Printing speed - It is a main indicator for calculating the production capacity of printing press. The calculation unit for sheet fed printing press should apply the printing times per hour (printing times / h); and the calculation unit for web printing press should apply the revolution number of printing cylinder in each hour (number of revolution / h)
Cylinder bearer contact - Cylinder bearers are the raised annular steps on both sides of printing cylinder. During printing, two cylinder bearers contact and roll against each other, which is known as cylinder bearer contact.
Color efficiency - It refers to the percentages of the correct and incorrect light absorptions by color.
Crystallization of ink - In the process of multi-color overprinting (cover printing), if the first ink contains too much desiccant or its storage time after printing is too long, the ink film will be excessively dry and become a smooth and mirror-like diaphragm, which causes the printing failure or uneven printing of the second ink and leads to the appearance of some knobs related to balls or spots with light color that can be wiped off or fallen off by soft touch.
Scumming - Non-printing area gets inked due to undesirable wetting of printing plate.
Rear exposure - Irradiation on the rear surface of flexographic plate.
Surfactants - A material that is able to significantly reduce the surface tension of solvent.
Color sequence - The colors of presswork are overprinted with inks of different hues, and the order of overprinting inks is called color sequence.
Picking - It refers to the situation where the ink layer rips paper surface during printing.
Surface tension - Surface tension (surface tension coefficient) (γ) (liquid or solid). The tension the internal molecule has for surface molecule.
Relative contrast - It is also called printing contrast signal, simply called as K value, which is an important parameter for controlling image toning. Measure the solid ink density as Dv and the integrated halftone density as DR in presswork or control strip, and put them into the formula below to calculate K value. K=(DV-DR)/DV or K=1-DR/DV
Waterless offset printing - Waterless offset printing is lithographic printing that adopts inked silicone rubber layer as non-printing area of printing plate in lithographic plate without dampening and is printed with special ink.
Imprint cylinder - It is also called cylinder for undertaking printing. It is a cylindrical drum that contacts with printing plate cylinder to produce printing pressure and complete printing process, which is a material that sustains printing.
Reflection copy - The original manuscript that is recorded with non-transparent media.
Three primary color of pigment - Yellow (Y), magenta (M), cyan (C).
Additive color mixture - It refers to the effect that two or more than two colors are mixed together to produce another color.
Object original - It is the general name for taking material object as copy target in reproduction technology.
Long-run printing - It refers to printing on a large scale.
Offset printing - It refers to planographic printing.
Original - It refers to the graphic information on the material object or the vehicle on which the platemaking is based.
Lightness - It is the shade degree of color that can be sensed by human’s eye and it’s a property related to the psychology and physiology of human.
Fluffing speed - It refers to the lowest printing speed at which the crumbs of paper appear in printing process.
Endurance of printing plate - Different plates have different endurances, which is determined by the surface structure of printing plate and the material properties of graphic and non-printing area.
Printing plate - It refers to the printing plate whose surface is divided into a part with transferable printing ink and another part with non-transferable printing ink. National standard explanation is: “In order to copy text and picture, it is an analogic picture carrier that is used for transferring color agent / pigment (such as ink) to printing stock.”
Ink - Printing ink is slurry colloid consisting of well-mixed pigment, ink vehicle and filler. As the ink is viscous fluid, its performance varies according to its type. The differences exist in thickness, viscosity, drying speed and so on.
Cylinder-packing - The enveloping material around cylinder.
Wet printing - The ink of another color is overprinted before the previous ink becomes dry
Dry printing - The ink of another color is overprinted when the previous ink becomes almost dry
Dampening formula - γSG =γSL +γLG cosθ or γSG -γSL =γLG cosθ
Saturated density - When the density reaches a certain degree and will increase no more, and the density is saturated density.
Ink-water balance - Under certain printing speed and pressure, the supply of fountain solution is regulated to ensure the volume ratio of fountain solution contained by emulsified ink is 15% ~ 26%, so as to form W/O type emulsified ink with a slight extent of water-in-oil and contend with the ink amount on printing plate with minimum supply amount.
Hysteresis effect of paper - The balance is reached through moisture absorption, and the moisture content of paper A is higher than that of paper B after balance. Such phenomenon is known as the hysteresis effect of moisture content of paper.
Rubber cylinder - Cylindrical drum that supports, clamps and tightens rubber blanket and transfer text and picture.
Three primary colors - Red (R), green (G), blue (B)
Selective adsorption - Selectively have affinity with certain surface.
Humidifying treatment - Hanging and drying paper in drying shop before printing to ensure the paper reach to balanced moisture content under the temperature and humidity of drying shop after a period of time. After hanging and drying, the moisture content of paper will be uniform and the dimension stability will also be improved.
Intermediate color - It is created by mixing two primary colors, also called as secondary color. Red + Yellow = Orange, Yellow + Blue = Green, Red + Blue = Purple. Orange, green and purple are three intermediate colors. Three primary colors and three intermediate colors are standard colors.
Ink transfer percentage - The ratio of the inking amount transferred to printing plate by an ink roller to total inking amount transferred to printing plate by all ink rollers.
Powder - It’s a product frequently used in offset printing mainly to prevent printing sheet from being sticky and dirty because of the incomplete drying of ink.
Ink left - It refers to the amount of ink that returns to printing plate after the transfer.
Indirect printing - It is a printing method that transfers the ink of text and picture in the printing plate to the surface of printing stock with the transmission of intermediate vehicle.
Anilox roller - It’s the most important component for the inking device of flexographic plate printing press, as well as the most major characteristic of flexographic plate printing press.
Lingering cylinder bearer - There are certain clearance between two cylinder bearers, which is lingering cylinder bearer.
Electrostatic ink absorption - To improve the ink transfer rate by electrostatic method.
Mechanical anchoring effect - It refers to the phenomenon that part of the ink transferred to the surface of printing stock material fills in hollow or clearance to attach ink to the surface of printing stock, which is like anchoring effect.
Contact angle - In the border of three phases, the angle between solid-fluid plane and tangent line of fluid surface is contact angle, expressed as θ.
Ink level of printing plate - The ink level supplied by printing plate.
Ink transfer rate - It is the ratio of the amount of transferred ink (referred to as y) to the ink level of printing plate (referred to as x).
Contact width of impression surface - It is the width of imprinted surface.
Compound color - It is created by mixing three primary colors of different percentages or mixing the intermediate colors. It is also known as tertiary color. Because there are three primary colors in it, it contains black element and has low purity. Compound color has a great variety to make many changes.
Printing plate cylinder - It is the cylinder with alloy steel as substrate, it is manufactured through process and is hard to deform due to dynamic balancing treatment.
Direct printing - It means directly transferring graphic information from printing plate to the printing stock.
Color intensity - The highest density among 3 density values measured by three-color filter of color densitometer indicates the color intensity of ink.
Registering - It means that different color patterns are required to be overlapped and registered for multi-color printing
Cylinder bearer undercut - It refers to the volume that is lower than cylinder bearer.
Screen angle - Screen angle describes the direction of arrangement of screen dot.
Wet imprint and overprinting - When four-color offset press conducts printing, the printing time between each color is extremely short, so that the ink of latter color adheres to the wet ink film of previous color, which is known as wet imprint and overprinting.
Continuous tone - It is continuous and gradual picture tone.
Neutral gray - It refers to the shade that absorbs or reflects three primary colors with equal proportion.
Natural humidity conditioning - It is also known as paper hanging method, that is, hanging paper in printing shop to ensure both the temperature and humidity of paper and printing shop reach balance.
Color separation - It is the process to separate color original into four color printing plates of yellow, magenta, cyan and black.
Color sequence - It means that in multi-color printing, color plates are successively overprinted in printing stock by certain color sequence.
Part II Short-answer Questions
What is the basic law for mixing three primary colors with each other?
A: ① Yellow + Magenta = Red;
② Yellow + Cyan = Green;
③ Magenta + Cyan = Blue;
④ Yellow + Magenta + Cyan = Black;
⑤ The more mixture, the darker the pigments are;
What is the basic principle of “achromatic color construction”?
A: ① In four-color offset printing, the process of replacing the compound color part formed by yellow, magenta and cyan color plates with black plate is achromatic color construction process;
② The tone of ink plate is relatively long;
What matters should be paid attention to when keeping printing ink?
A: ① Sealed storage;
②Use the previously stored ink first;
③ Pay attention to ℃ and RH;
④ Fire protection;
⑤ Keep from hazardous substances;
⑥ Ink tank gets rusty;
What are the contents of three elements to strictly control printing pressure?
A: ① Accurate center distance of cylinder;
② The linear speeds on cylinder surface must be equal;
③ The optimal substance for rubber blanket extrusion deformation;
What are safety control devices for paper feed unit of sheet-fed offset press? How do they function?
A: The safety control devices for paper feed unit of sheet-fed offset press include:
(1) Double sheet controller, which can be divided into mechanical fixing type, mechanical swing type and photoelectric type, with a function of preventing double or multiple sheets from entering cylinder and being printed.
(2) Blank sheet or askew sheet controller, which can be divided into front lay voltage detection and photoelectric detection, with a function of preventing askew sheet from entering into cylinder and being printed.
(3) Paper feed safety bar, which is used for preventing other materials entering into cylinder and being printed.
What are the features of offset printing as indirect printing?
A: Small printing pressure, less printing plate abrasion, good adaptability to paper, fast printing speed, relatively small dissipation for machine, no contact between paper and printing plate, thus ensure the dimension stability of paper.
What is the main structure of modern offset press and what are the functions of its components?
A: ① Paper feed: Feed paper to front lay;
② Paper feed positioning system: Feed paper to the position of cylinder;
③Printing system: Transfer graphic and text;
④ Inking: Supply ink to printing plate;
⑤Dampening: Supply “water” to printing plate;
⑥ Paper delivery: Collect press work;
How does the amount fountain solution respectively relate to ink property, ink loading amount of graphic and text, paper property and ambient temperature?
A: If ink is of high viscidity and low liquidity (dense ink), the amount of solution should be reduce. And water volume should be increased if ink is thin;
If the ink loading amount of graphic and text is large, the solution amount will be large; conversely, the solution amount will be small;
Solution amount will be increase under higher temperature; and it will be reduced under lower temperature;
Paper with loose texture will increase the amount of fountain solution;
Acid paper will reduce the amount of solution and alkalic paper will increase the amount of solution.
How to determine that the water volume in offset printing is too large?
A: 1) Observation: Observe the water volume on printed sheet or observe the reflectance on printing plate from side.
2) Auxiliary determination method: Determine the water volume by listening to the noise of operation of equipment or other measures.
3) Water film measurement method: Measure the thickness of ink on printing plate with special ink measuring instrument.
Briefly describe the method to control the color quality of printed picture.
A: ① Regulate printing pressure according to specific production condition.
② Arrange color sequence properly
③ Calibrate printing press
④ Control the temperature of inking device.
⑤ Control ink supply amount.
⑥ Control water supply amount.
What are the types of paper?
Paper, by its weight, can be divided into: sheet and paperboard.
Generally, paper weighted less than 250G / M2 is sheet, and paper weighted more than 250G / M2 is paperboard.
Typical printing sheet and paperboard refer to the paper used for printing newspaper and magazine, book, picture album and ticket.
(1) News printing paper: Commonly known as newsprint, it is applied to printing newspaper and some magazines and books with lower quality requirements.
(2) Offset printing coated paper: It is commonly known as coated paper. It is divided into one-side coated paper and two-side coated paper.
Why does the amount of compression deformation indicate printing pressure in printing?
A: According to Hooke’s law: F/S=E△L/l
“F” refers to printing pressure, “S” refers to the amount of compression deformation of contact area, △L refers to deformation amount, l refers to original length, E refers to elastic inking.
The changes of F and △L are directly related, so the amount of compression deformation is able to indicate printing pressure.
How to make correct evaluation on the quality of presswork?
A: Evaluation on production quality consists of subjective evaluation and objective evaluation. Subjection evaluation is making visual observation and comparison on products based on personal feelings experience, such as color shade, brightness and full of screen dot, richness of layer and cleanness of plate surface, all of which are subjective.
Objective evaluation requires the assistance of some test instrument, for instance, densitometer. Through the signal bar and control strip dried on specimen paper, test the data including the increase of compared dots of solid density and standard density, relative contrast and gray balance to feedback the quality of presswork.
Therefore, subjective evaluation and objective evaluation should be in organic combination so as to make correct evaluation and control the quality of products during production.
What are the conditions for keeping the balance between water and ink?
A: The conditions are:
(1) There must be firm foundation of graphic and text and blank foundation on printing plate;
(2) The thickness of sand hole should be uniform and compact with certain mechanical strength to ensure a foundation for solid absorption of graphic, text and blank and a good water storage condition;
(3) Workshop temperature is constant;
(4) Mechanism operates at uniform velocity, and machines should operate at normal constant speed and uniform velocity during production. Unstable operation of machine will easily result in ink-water imbalance;
(5) Ink-water balances are varied according to different inks and paper properties.
(6) Control PH value of fountain solution to avoid large fluctuation.
(7) Properly regulate the pressure of ink roller and water roller of printing plate.
What do the datamation and standardization of printing mean?
A: Datamation of printing means that In the procedure of printing, through necessary testing methods, find reliable data that meet the requirements of product quality under various conditions and are able to conduct repetitive production in all processes or operations that can be expressed by data, and the said data will used for guiding production.
Standardization means that to further study process technology on the basis of datamation, and summarize them as a law to guide production, and set operation standards for all process technologies. In this way, appropriate technological measures can be taken according to the category of original and the conditions of all ink and paper, and all process technologies can follow rules and standards.
What is screen dot and how does it work in offset printing?
A: Screen dot is the pixel that composes picture. Its accurate transmission in all processes is the basic unit of plate making and printing. Its functions in offset printing are:
(1) It is responsible for presenting hue, brightness and chroma in terms of printing effect.
(2) In printing procedure, it is the minimum unit of lipid sense and water rejection and is the basic element of picture transmission.
(3) It is the organizer of color, layer and profile of picture in terms of color composite.
How to understand ink-water balance correctly?
A: In actual printing, there is no ideal ink-water balance which is only a concept of relativity.
The ink-water balance of offset printing is realized under dynamic state, which means: Under certain printing speed and printing pressure, regulate the supply amount of fountain solution to ensure the volume ratio of fountain solution contained in emulsified ink is 15% - 26% to form W/O type emulsified ink with a slight extent and to contend with the ink on printing plate with minimum supply amount.
What is printing pressure and how does it work?
A: When printing, the perpendicular force between the contact surface of cylinders and surface press is known as cylinder pressure, also known as printing pressure. Its functions are:
(1) Keep the full contact of rough printed surfaces.
(2) Overcome the attractive force of ink molecules to increase absorption force.
(3) Ensure the permeation of pressure.
What is the ideal pressure for offset printing? What are the factors influencing the ideal pressure of offset printing?
A: The ideal pressure for offset printing is: Under the certain condition of deformed printing surface, on the basis of imprint that is strong enough apply the minimum pressure of 0.10 mm uniformly.
The ideal pressure for offset printing is influenced by:
(1) Improper regulation of center distance between two cylinders.
(2) Uneven thickness of printing plate;
(3) Uneven surface of rubber blanket;
(4) Poor contact between inking roller and surface of printing plate;
(5) Dirty materials on the surface of cylinder bearer or rubber blanket;
(6) Improper packing;
What is cylinder-packing? How does it work?
A: In printing procedure, the packing material on the surface of cylinder is cylinder-packing. Its functions are:
(1) Counteract the deviations on printing pressure which are caused by the thickness of printing cylinder, selected printing plate, rubber blanket and paper to ensure good contact of printing surfaces.
(2) Absorb the vibration and impact occurred in imprint contact area of printing cylinder under dynamic loading.
(3) Change the amount of extrusion deformation to regulate printing pressure.
(4) Complete the transmission and transfer printing of graphic and text.
What is the basic principle of proper packing? Briefly describe the operation steps.
A: The basic principle of proper packing is: Under the certain condition of deformed printing surface, on the basis of imprint that is strong enough and good reproduction of screen dot, the minimum pressure should be applied uniformly to improve the endurance of printing plate and reduce the burden of cylinder gear.
Its operation steps are:
(1) Measure and calibrate the center distance of cylinder accurately;
(2) Calculate and measure the thickness of padding materials of cylinder accurately;
(3) Choose ideal padding materials and increase the minimum padding thickness within the limit to ensure that the contact pressure can reach ideal situation;
(4) Adopt full plate method, reduce the thickness of padding in rubber blanket by 0.40 mm or so (compared with normal value), and inspect the unevenness of rubber blanket after the inking and closing of full plate.
(5) Effectively smooth the unevenness of rubber blanket.
What concept lies in the sheet transfer of transfer gripper under static state or relatively static state?
A: Sheet transfer of transfer gripper under static state means that the instantaneous velocity of transfer gripper is zero when receiving paper. And sheet transfer of transfer gripper under relative static state means that the speed is same with the machine parts for receiving paper at any point of any time period.
What does the transfer relation include in the procedure of transferring paper of offset press?
A: In the procedure of transferring paper, the transfer relation includes two aspects:
The first aspect is transfer position, which refers to the relative position of two transfer machine parts when transferring. Set one machine part as the benchmark to adjust the position of the other machine part, so that the position of the latter matches with the benchmark machine part. The regulation of all transfer positions must follow an order.
The second aspect is transfer time, which refers to time for controlling paper simultaneously at the transfer position (nearby) by transferring machine part, that is, the time starts when the transferring machine part is controlling paper while the paper receiving machine part starts to controlling paper, and after a while it ends when transferring machine part lifts the control over paper.
The sequence of transferring time at all positions is not required. As long as the transferring position is correct, the transferring time can be regulated.
What is concession value of cylinder? Briefly describe the general method for inspecting concession value.
A: There are certain fitting clearance between cylinder journal and shaft sleeve and eccentric sleeve and between eccentric sleeve and wall plate hole. Under off-pressure condition or during printing or under circumstance where the cylinder gap is relative to the original printing pressure, all the gaps will concentrate over the top of axle bearing due to the dead weight of cylinder. Once the pressure is closed, cylinder will expand outward along the direction of combined forces of printing pressure and gravity, and the locations of gaps will deviate and move to the opposite directions of combined forces of all acting forces of cylinder. The phenomenon that the deviation of gap and concession movement of cylinder center takes place as the result of changing forces is known as concession whose value is the concession value of cylinder.
The general method for inspecting concession value is: Pack the printing plate cylinder and blanket cylinder in the manner of packing method under normal printing, close the pressure, use electrical fuse with a diameter of 0.5 mm to press two segments respectively in the space between cylinder bearers on the working side of cylinder and the space between cylinder bearers in the gap, then measure the thickness of this two segments with micrometer, and the difference of two thickness values is concession value of cylinder.
What are the main factors influencing the amount of fountain solution?
Key points of answer: Including the surface tension of fountain solution, water absorption of ink, water absorption of paper, thickness of ink layer and ambient temperature.
Can you apply dampening formula to analyze the conditions for fluid to spread out on solid surface?
A: Under constant temperature and pressure, the change of free energy of system on unit spreading area is ΔG=γSL-γLG-γSG, the power done by system to the outside is W=S=γSG-γSL-γLG , and S is spreading coefficient.
Under constant temperature and pressure, the condition for fluid to automatically spread out on solid surface is ΔG=γSL+γLG-γSG≤0 or S=γSG-γSL-γLG≥0. If (1-9b) is substituted into (1-11b), then S=A-γLG. When S ≥ 0, A ≥ γLG. When the adhesive tension between fluid and solid is higher than the surface tension of fluid, fluid will spread out on solid surface automatically.
How to control the water consumption of printing plate?
Key points of answer: As long as the plate is not smeared, the less water, the better.
Briefly describe the reasons of inaccurate registering caused by machine.
Key points of answer: Paper on printing press is transferred to front lay gauge by flowing conveyer belt. When the front end of paper reaches this position, front lay gauge will rise from the bottom to top to stop paper from moving forward. As the conveyer belt transfers paper at a pretty high speed, therefore, once paper touches the front lay gauge, distorting and upturning will tend to take place easily.
Whose printing pressure is larger between thin screen printing plate and thick screen printing plate? Why?
Key points of answer: Thin screen printing plate requires less printing pressure, or level merging of screen will be caused.
How to define the mesh count, aperture width and aperture ratio of screen mesh?
Key points of answer: Mesh numbers contained in per square centimeter of screen mesh is called the mesh count of screen mesh. The aperture width of screen mesh is used for measuring the side of mesh, indicating the width of mesh and expressed as the square root of mesh area consisted of the longitude and latitude lines of mesh. Aperture ratio of screen mesh is also called as open cell rate of screen mesh, effective filtering area or mesh area percentage, i.e. the percentage the mesh area accounts for in the unit area of screen mesh.
What are the main deformations that are likely to occur to rubber blanket in planography? How do they influence printing quality? Is there any preventive methods?
Key points of answer: The main deformations include sensitive elastic deformation, anelastic deformation and plastic deformation. Sensitive elastic deformation will result in printing pressure and has a direct impact on printing quality. The influence of plastic deformation can be ignored.
Try to explain the basic theory of ink-water balance in planography.
Key points of answer: A little ink is emulsified, counteracting ink with minimum water.
Describe the function of surfactant in the fountain solution.
Key points of answer: The one head of surfactant molecule is polar hydrophilic, the other head is non-polar hydrophobic. The hydrophobic head is repelled to and concentrate on the surface, producing attractive force to water surface, weakening the inward pulling force borne on surface molecule and reducing the surface tension of fountain solution.
What are the common shapes of ink hollow of anilox roller used in flexographic plate printing press? What is the characteristic?
Key points of answer: The most serious corner effect exists in Quadrangular pyramid ink hollow. Anilox roller with quadrangular frustum ink hollow has better ink release performance, and hexagonal frustum ink hollow is the improved version. Ink hollow of additional channel is the improvement of truncated pyramid ink hollow, with a sound ink transfer performance in diagonal shape.
How to determine the ink level of printing plate and transferred ink level?
Key points of answer: The ink level of printing plate is determined by deducting printing plate weight from gross weight, and the transferred ink level is determined by deducting left ink level from the gross weight.
To improve the ink overprinting effect of multi-color offset press, what problems should be paid attention to?
Key points of answer: Inks used in four-color offset press generally are arranged in the order of cylinders of all units, gradually lowering the adhesivities of inks.
In waterless offset, non-printing area will not get inked without fountain solution, describe the principle.
Key points of answer: For waterless offset printing, there is an affinity between the silica gel layer of the printing plate and the connected substance (solvent) of the solution. When the two contact, the solution diffuses and penetrates quickly to the silica gel layer. The surface of the silica gel layer then swells, and the contact surface forms a solution layer (2 points). As ink cohesion exceeds solution cohesion, the splitting starts from the solution layer and there is no ink on the silica gel layer (2 points).
What are the advantages and disadvantages of ethyl alcohol fountain solution?
A: The Ethanol improves the spreading performance of fountain solution on printing plate, reduces the fountain solution used and cuts the printed sheets dipped in oil and the severe emulsification of ink. A plenty of heat energy is lost when Ethanol volatilizes, thus reducing the temperature of plate surface and ensure the non-graphic and text area will not be easy to get dirty. Ethanol volatilizes at a higher speed, which, without control, will reduce the concentration of fountain solution. Meanwhile, the temperature of fountain solution should be controlled under 10 ℃ as far as possible to diminish the volatilization of Ethanol. Ethyl alcohol dampening system without swinging water transferring roller is generally applied to continuously provide fountain solution to printing plate, equipped with auxiliary devices for fountain solution circulating cooling and automatically replenishing Ethanol.
For the ink transfer rate of form inking rollers, which roller arrangement do you think is most conducive to ink transfer?
Key points of answer: Asymmetric arrangement of rollers can facilitate ink transfer. The ink roller in the back has lower ink transfer rate due to its function of ink distribution and collection.
With the same printing press, which kind of paper, the coated paper or offset paper of 120g/m2 will need more printing pressure? Why?
Key points of answer: The offset paper will need more printing pressure. Its rough surface needs more pressure to allow ink to penetrate into the paper.
Describe the ink transfer performance of the anilox roller- scraping blade inking system used by the flexographic press.
Key points of answer: The structure is simple with better scraping and ink transfer performance.
What are the criteria for subjective evaluation and objective evaluation of presswork quality? How to make more accurate evaluation of presswork quality?
Key points of answer: Presswork quality is evaluated subjectively, objectively and comprehensively. Objective evaluation uses some test methods to determine the quality characteristics of presswork, which is expressed with numerical values. Comprehensive evaluation is based on the numerical values of objective evaluation. By comparing with various factors of subjective evaluation, a set of common evaluation criteria is obtained.
During printing, why ink in the fountain needs to stay at a certain liquid level?
Key points of answer: Low level means short contact length with ink foundation roller, which will lead to a small shear force for printing ink that reduces ink volume.
In how many ways could printing pressure be expressed?
A: The stamped face could be accurately seen as a rectangular plane. The long side of the rectangle (L) equaling to the effective length of the stamped material, is called stamped face length and do not change with pressure; the short side of the rectangle (b) is called stamped face width and changes with pressure. Please see Fig. 2-1. Generally, b is measured in the unit mm; however, L is usually measured in 2 orders of magnitudes bigger than that of b. Therefore, the stamped face is a ribbon plane. Compared with L, b can be overlooked in measurement, and then the stamped face is transformed into a straight line with a length of L; the average pressure PL on L is called linear pressure and pL= ps/ L.
How to improve the overprinting precision of presswork in terms of paper fiber arrangement?
Key points of answer: The paper of horizontal grains is thick and easy to print; however, it is very likely to have trumpet-shaped stretches; the paper of vertical grains is softer, making it hard collect and feed sheets. For the planographic press, it is difficult to adjust the size of the image-text that has the same axial direction with the printing plate or rubber sheeting. However, the size of the image-text in same circumferential direction with the roller can be adjusted slightly by increasing or decreasing the thickness of cylinder packing.
What are the differences between the cylinder packing used by the high-speed press and low-speed press? Please give your reasons.
Key points of answer: As the high-speed press needs more printing pressure, hard cylinder-packing should be chosen.
How many kinds of commonly used silk screens? What is the characteristic?
Key points of answer: There are natural silk screen, nylon silk screen, dacron silk screen, stainless steel silk screen and other silk screens in silk-screen printing.
Fountain solution is very important in offset printing. Please describe its functions.
Key points of answer: (1) Wetting. The non-printing area of the printing plate forms a water film, which can prevent ink penetration and scumming (2 points); (2) Supplementing. The friction between the ink, water or rubber roller and the printing plate causes abrasion. Moreover, lints make abrasion worse. The hydrophilic water film of the printing plate is thus destroyed. The electrolyte in the fountain solution will react with aluminum or zinc, forming a new hydrophilic water film (1 point); (3) Cooling. The printing ink temperature of the plate could be controlled (1 point); (4) Cleaning. The fountain solution could clean up ink dots and smudges on the non-printing area (1 point).
When the cross mark is used to check misalignment, will printing sequence have impact on it? Please show your reasons.
Key points of answer: For the single-color press, the printing sequence of black, cyan, pinkish red, and yellow (transparent yellow ink) may be adopted; the sequence of yellow (non-transparent yellow ink), cyan, pinkish red, and black may also be adopted. For a misalignment of the colors black and cyan, if the two colors are aligned at the gripper edge whereas are not aligned at the paper tail, and the color black has been moved within the color cyan, which means the black cross mark is farther from the paper tail, then in this case, the misalignment is not caused by paper shrinkage.
What are the criteria for subjective evaluation and objective evaluation of presswork quality? How to make more accurate evaluation of presswork quality?
Presswork quality is evaluated subjectively, objectively and comprehensively. Objective evaluation uses some test methods to determine the quality characteristics of presswork, which is expressed with numerical values. Comprehensive evaluation is based on the numerical values of objective evaluation. By comparing with various factors of subjective evaluation, a set of common evaluation criteria is obtained.
For the ink transfer rate of form inking rollers, which ink roller arrangement do you think is most conducive to ink transfer?
Key points of answer: Asymmetric arrangement of rollers can facilitate ink transfer. The ink roller in the back has lower ink transfer rate due to its function of ink distribution and collection.
What is the relation between the wetting of the ink layer surface and the time used for ink drying?
Key points of answer: The second color should be printed 8 hours after the first color is printed. In this way, the rate of ink trapping is the highest with the best effect. However, a printing interval of 8 hours is not easily to be realized in actual printing.
Please describe the theory of waterless offset printing.
Key points of answer: For waterless offset printing, there is an affinity between the silica gel layer of the printing plate and the connected substance (solvent) of the solution. When the two contact, the solution diffuses and penetrates quickly to the silica gel layer. The surface of the silica gel layer then swells and the contact surface forms a solution layer. As ink cohesion exceeds solution cohesion, the splitting starts from the solution layer and there is no ink on the silica gel layer.
Use the relation curve between ink transfer rate and printing pressure to analyze the impact of printing pressure on printing quality.
A: In the AB section where the pressure is too low, the degree of compression is too small. The ink could not fully contact with the paper, leading to incomplete prints and low printing quality. In the BC section where the pressure increases, the ink transfer rate also increases, the ink color of presswork gradually improves. The C point is the turning point of reasonable pressure with pc being the required minimum pressure, and the ink color is satisfying. The D point is the turning point of too much pressure with pd being the required maximum pressure. Once the D point is passed, the dots will be severely enlarged with sliding, friction, and abrasion. The appropriate printing pressure should between pc and pd where the printing quality being the best.
What are the similarities and differences of the linting of papers on single-color offset press and multi-color offset press?
Key points of answer: The linting of papers depends on the surface strength of the paper and printing conditions. Under the same conditions, in other words, when the ink, rubber sheeting, and rolling speed of rollers are the same, enough surface strength is required; otherwise, good printing conditions are required.
How to determine the best ink layer thickness?
Key points of answer: (1) Measure the solid density and 75% dot intensity of printing samples of different ink layer thickness (1 point); (2) Calculate the relative contrast value of different samples (2 points); (3) Determine the ink layer thickness of the sample with the biggest relative contrast value, thus having the best ink layer thickness.
What should be paid attention to the use of fountain solution of non-ionic surfactant?
Key points of answer: The volume of the surfactant shall not exceed 1/1000, otherwise the emulsification of ink would increase.
What is the relation between the water content of paper and the changes of temperature and humidity?
Key points of answer: There is always water content in the paper, but it changes with the temperature and humidity around. Absorb water content from air of a certain temperature and relative humidity, or water content is escaped into air of a certain temperature and relative humidity, until there is a balance between the vapor in air and in the paper. At this moment, the water content in the paper is called the water content under this temperature.
What is the harm of static electricity in printing?
Key points of answer: First is the static electricity carried by printing substrates, for example, papers or polyethylene and cellophane used for special printing. Static electricity-carrying papers can be harmful in many ways: papers can be adhered together because of mutual affinity; papers could not be collected neatly because of mutual repulsion. All these make printing operation become hard. Such papers may also adhere paper scraps or other impurities, which affect printing quality; what is worse, air discharge could be also caused by ultra high voltage, leading to electric shocks or fires.
For the same kind of paper, when it is printed on outline printing presses A and B, respectively, if the roller radius of A is smaller than that of B, then which press needs more printing pressure? Why?
A: The larger the radius, the higher the printing pressure. This is because of b=2(2?R1?R2?λ/(R1+R2) ps=(1/2)(1+q)(1-(1/3n))?b?L?pmin
How to choose the line number of anilox roller based on anilox roller line number matching figure?
Key points of answer: With the given screen number of plates, the matched number of anilox roller lines could be calculated and vice versa.
Use the relation curve between ink transfer rate and printing pressure to analyze the impact of printing pressure on printing quality.
A: In the AB section where the pressure is too low, the degree of compression is too small. The ink could not fully contact with the paper, leading to incomplete prints and low printing quality. In the BC section where the pressure increases, the ink transfer rate also increases, the ink color of presswork gradually improves. The C point is the turning point of reasonable pressure with pc being the required minimum pressure, and the ink color is satisfying. The D point is the turning point of too much pressure with pd being the required maximum pressure. Once the D point is passed, the dots will be severely enlarged with sliding, friction, and abrasion. The appropriate printing pressure should between pc and pd where the printing quality being the best.
How to use the cross mark to check whether the misalignment of paper is not caused by paper distortion?
Key points of answer: When making the plate, one should mark cross marks in the four corners and in the middle of the plate. The marks should be cut off with deckle edges after printing is finished. In multi-color printing, the misalignment of presswork could be checked through the degree of the mismatching and skewing of cross marks.
During printing, how to reduce the friction of rolling?
Key points of answer: The thickness of roller cylinder packing and the degree of compressive deformation should be reasonably allocated.
In silk screen printing, what qualities should the silk screen have?
Key points of answer: Required by the plate-making and printing in silk screen printing, the silk screen should have high tensile strength, low elongation at break and good rebound resilience to make silk screen plates with high tensile strength and good plane stability.
Use the relation curve between ink transfer rate and printing pressure to analyze the impact of printing pressure on printing quality.
A: In the AB section where the pressure is too low, the degree of compression is too small. The ink could not fully contact with the paper, leading to incomplete prints and low printing quality. In the BC section where the pressure increases, the ink transfer rate also increases, the ink color of presswork gradually improves. The C point is the turning point of reasonable pressure with pc being the required minimum pressure, and the ink color is satisfying. The D point is the turning point of too much pressure with pd being the required maximum pressure. Once the D point is passed, the dots will be severely enlarged with sliding, friction, and abrasion. The appropriate printing pressure should between pc and pd where the printing quality being the best.
Why there is a need to reduce the number of stopping printing? What is the point in using transfer paper?
Key points of answer: To continue printing after stopping, ink volume and ink-water balance should be adjusted, which consumes time and materials. After printing is stopped, the volume of the roller ink near the plate increases, and the transfer paper is needed to take away the excessive ink.
How to control the thickness of ink layer on the planographic press?
Key points of answer: Control the nook or rolling speed of the ink roller; control the gap between the fountain blade and the ink foundation roller; control the contact pressure and contact time between the distributor roller and the ink foundation roller.
Part III Choice Questions
Visual inspection of the presswork quality belongs to (A).
A. subjective evaluation B. objective evaluation
C. comprehensive evaluation D. none
During planographic printing, the enlargement of dots is not related to (B).
A. the volume of printing ink B. the color of printing ink
C. printing pressure D. liquidity of printing ink
The anilox roller is mainly used in (C)
A. planographic printing B. intaglio C. flexographic printing D. porous printing
In flexographic printing, the inking of the anilox roller is (B).
A. spreading B. soaking C. soaking D. uncertain
In offset printing, if there is too many water contents, the transparency of the printing ink will (B).
A. increase B. decrease C. stay the same D. uncertain
The CPC 5 of Heidelberg printing computer control system is (D).
A. register control device B. quality control device
C. press control device D. data management system
Dry overprinting is not used in (B).
A. single-color offset press B. multi-color offset press
C. intaglio printing press C. rotary flexo press
Fountain solution is used in (A).
A. planographic printing B. intaglio C. flexographic printing D. porous printing
In traditional offset printing, the surface tension of printing ink is (A) that of fountain solution.
A. a little higher than B. a little lower than C. equals to D. with no influence
In the inking system of the offset press, the ink is transferred in the way of (A).
A. multi-ink roller B. anilox roller C. scraping blade D. ink transfer roller
If the roller diameter of the printing plate of the rotary flexo press is the same, the thinner the flexographic plate, the (A) the distortion of the plate roller.
A. higher B. lower C. stay the same D. uncertain
The friction of the form dampening roller, form inking roller, and printing plates (A) dots.
A. enlarges B. shrinks C. stay the same D. none
To determine the weight of papers before and after printing is to measure (B).
A. the ink volume of the printing plate B. the transferred ink volume
C. the left ink volume D. the measured ink volume
In multi-roller inking system, the larger the ink-evening coefficient, the (C) the ink-evening performance.
A. stay the same B. uncertain C. better D. worse
The “crystallization” of the ink layer of the presswork is caused by (A).
A. drying too fast B. drying too slow
C. being placed for a long time D. being placed for a short time
Water and ink do not mix together and this is because (C).
A. both water and ink are polar. B. both water and ink are non-polar.
C. water is polar whereas ink is non-polar D. water is non-polar whereas ink is polar
In the formula of ink-transfer rate, y refers to (D).
A. free ink volume splitting rate B. the filling limit of ink volume
C. the transferred ink volume D. the ink volume of printing plates
As shown by experiments, for the rubber roller wrapped by the rubber sheeting, when it is rolled on a surface because of pressure, its contact length with the surface (A).
A. increases B. decreases C. stay the same D. uncertain
In traditional offset printing, ink-water balance refers to (D).
A. a certain proportional relation between ink and water.
B. water volume is smaller than ink volume
C. ink volume is smaller than water volume
D. Under the condition of no scumming, the less the water, the better.
The reason for oil-in-water emulsion is (B).
A. ink volume is larger than water volume B. water volume is larger than ink volume
C. ink volume is the same with water volume D. the volumes of ink and water are uncertain
In lithographic plate burning, the PS plate and the negative sensitive layer is placed face-to-face. This is because (B).
A. to prevent exposure of the part that should not be exposed
B. to ensure the sealing of the printing plate and negative layer
C. to reduce exposure time
D. to prevent chemical reaction of the sensitive layer of the printing plate
The treatment of the plastic film before printing is to (A).
A. increase surface tension B. decrease surface tension
C. degrease D. prevent static electricity
The prerequisite to wetting of S =γLG (cosθ- 1)≥ 0 is (A).
A.θ≤90° B.θ≥90° C.θ≤0 D.θ≥0
The malfunction of waterless offset printing in low or high temperature is mainly caused by (C).
A. the softening of the silica gel layer of the printing plate
B. the malfunction of inking system
C. the malfunction of the press
D. the damage on the printing plate
Of the four rollers of the offset press, the former two has high inking rate, this is because the ink roller (D).
A. has a large diameter B. has a good ink affinity
C. has asymmetric arrangement D. is to be inked first
During printing, increasing ink viscosity could prevent (B).
A. transmission B. dip reflection C. set-off printing D. fogging
In the locking up of flexographic plates, the distortion rate of the printing plate is not related to (B).
A. the thickness of printing plates B. the length of printing plate
C. elastic modulus of the printing plate D. the radius of the printing plate roller
In the fountain solution of PS plates, which of the following can improve the hydrophily of printing plate (D).
A. citric acid B. phosphoric acid C. peach gum D. surfactant
The larger the diameter of the printing plate roller, the (B) the distortion rate of the PS plate on it.
A. higher B. lower C. stay the same D. uncertain
The prerequisite to wetting of S =γLG(cosθ- 1)≥ 0 is (A).
A.θ≤90° B.θ≥90° C.θ≤0 D.θ≥0
In offset printing, the more water, the (C) chromatography accuracy.
A. better B. stay the same C.worse D. uncertain
(B) makes the printing surface have a full contact.
A. printing speed B. printing pressure C. printing substrates D. ink volume
The thickness of the cylinder packing of rubber roller means the thickness of (C).
A. rubber sheeting B. padding C. padding and rubber sheeting D. none
In traditional printing, corrugated boards are commonly used in the printing of (D).
A. planographic printing B. intaglio C. hard relief block D. flexographic plate
During printing, the increasing of air humidity of the workshop is conducive to the prevention of (D).
A. transmission B. dip reflection C. set-off printing D. fogging
In offset printing, the excessive supply of fountain solution will lead to (BD).
A. scumming B. water traces C. have no influence D. cannot be printed
Wet overprinting is used in (B).
A. single-color offset press B. multi-color offset press
C. intaglio printing press D. rotary flexo press
In offset printing, the excessive supply of water will lead to (BD).
A. scumming B. water traces C. have no influence D. cannot be printed
Dry overprinting is used in (A).
A. single-color offset press B. multi-color offset press
C. dual-color offset press D. all offset presses
In offset printing, the dimming of part of dots is to (A) the dots.
A. enlarge B. shrink C. stay the same D. uncertain
(A) does not belong to traditional printing elements.
A. printing speed B. printing pressure C. printing substrates D. ink volume
In offset printing, if there is an excessive supply of ink, dots will (A).
A. enlarge B. shrink C. stay the same D. uncertain
In flexographic printing, the image-text with more screen lines is (D) than that with fewer screen lines in terms of definition.
A. higher B. lower C. uncertain D. with worse effect
The larger the excessive free energy of the surface of printing substrates, the (A) the wetting of the ink.
A. better B. worse C. medium D. uncertain
In offset printing, the dots in the part of catch light will (B).
A. enlarge B. shrink C. stay the same D. uncertain
The relative displacement of printing rollers will make dots (A).
A. enlarge B. shrink C. stay the same D. none
When the elastomer rolls with more pressure, its rolling trace (A).
A. increases B. decreases C. stay the same D. uncertain
Under the same printing conditions, the rule for the enlarging of dots is 50% of the value of dot enlargement (A) 80% of the value of dot enlargement.
A. is greater than B. is less than C. equals to D. uncertain
In offset printing, for the volume of ink used and the volume of fountain solution used, it is (A).
A. the volume of ink is used more B. the volume of fountain solution is used more
C. the two volumes are the same D. uncertain
In the inking system of flexographic press, the inking of (B) is adopted.
A. multi-ink roller B. anilox roller C. scraping blade D. squeegee
In fountain solution, the higher the density of surfactant, (C) of the fountain solution.
A. the higher the surface tension B. the lower the surface tension
C. the worse the emulsification D. the better the wetting
The higher the surface tension of fountain solution, the (D) of the wetting of the printing plate.
A. better B. worse C. medium D. uncertain
Dry overprinting is not used in (B).
A. single-color offset press B. multi-color offset press
C. intaglio printing press D. rotary flexo press
The prerequisite to wetting is (BC).
A.θ≥180° B.θ≤180° C.θ≥90° D.θ≤90°
(A) is the feature of the printing of flexographic plate.
A. kiss impression B. indirect impression C. impression with water D. rubber sheeting
In offset printing, compared with the ink thickness of the solid areas of black plates with that of the part of dots, (C).
A. the former is much thicker B. the former is relatively thicker
C. the two are the same in thickness D. the former is relatively thinner
In traditional offset printing, to print fine presswork, using (D) fountain solution is better.
A. common B. non-ionic surfactant C. strengthening water D. ethyl alcohol
In printing, (B) of the following is not the reason for dot enlargement.
A. reflection of light B. printing speed C. printing pressure D. liquidity of printing ink
The malfunction of waterless offset printing in low or high temperature is mainly caused by (C).
A. the softening of the silica gel layer of the printing plate
B. the malfunction of inking system
C. the malfunction of the press
D. the damage on the printing plate
In offset printing, the thick ink layer make dots (A).
A. enlarge B. shrink C. stay the same D. uncertain
When the elastomer rolls with more pressure, its rolling trace (A).
A. increases B. decreases C. stay the same D. uncertain
Printing pressure is caused by (B).
A. roller weight B. the distortion of cylinder packing
C. the changes of paper thickness D. the rolling of rollers
In printing, the reason for printing the ink with more transparency first is mainly because (C).
A. printing ink with more transparency has high viscosity
B. printing ink with more transparency has low viscosity.
C. printing ink with more transparency has less covering power
D. to prevent reverse-viscosity
The thick the printing plate, the (B) the distortion of the roller on the printing plate.
A. larger B. smaller C. stay the same D. uncertain
The reason why the reproducibility of waterless offset printing dots is better than that of traditional offset printing is (B).
A. the difference of printing plates B. there is no impact of water
C. waterless offset printing is advanced D. the press has a high precision
In flexographic printing, the image-text with more screen lines is (D) than that with fewer screen lines in terms of definition.
A. higher B. lower C. uncertain D. poor effect
In offset printing, when the printing roller is pressed, the sliding of the surface cannot be avoided. This is because (C).
A. the cylinder packing is too thick B. the rubber sheeting has loosened
C. the rolling radius is not the same D. the printing plate has loosened
The distortion of flexographic plates is not related to (B).
A. the thickness of printing plates B. the length of printing plate
C. the elasticity modulus of printing materials D. the roller radius of the printing plate
The CPC1 of Heidelberg printing computer control system refers to (C).
A. register control device B. quality control device
C. press control device D. image reading device of the printing plate
The inking of non-printing areas on PS plates is (B).
A. pasting plate B. scumming C. image plate D. uncertain
The fountain solution is (A).
A. acid B. neutral C. alkaline D. uncertain
In multi-roller inking system, the ink layer near the ink roller of the printing plate is (B) than that of the ink roller away from the plate.
A. larger B. smaller C. uncertain D. irrelevant
During the wetting process, the contact angle θ≤0 is the prerequisite to (A).
A. spreading B. soaking C. dipping D. wetting
The malfunction of waterless offset printing in low or high temperature is mainly caused by (C).
A. the softening of the silica gel layer of the printing plate
B. the malfunction of inking system
C. malfunction of press
D. scumming is likely to occur
The plastic film needs to be treated before printing. The way to treat it is (B).
A. stretching B. corona C. de-scumming D. destaticization
The function of Arabic gum in fountain solution is (A).
A. to increase wetting B. to keep the printing plate wet
C. to increase anti-abrasion of the printing plate D. has no function
The way the fountain solution adheres to the image-text of the PS plate is (C).
A. spreading B. soaking C. dipping D. none
To reproduce the color gradation of the original script by using the thickness of ink layer, one should adopt the printing of (B).
A. planographic printing B. intaglio C. porous plate D. flexographic plate
During the transfer of ink, if the paper is smooth, it means (A).
A. the value of K is large B. the value of K is small
C. the value of b is large D. the value of f is large
In offset printing, if there is a lack of ink supply, dots will (B).
A. enlarge B. shrink C. stay the same D. uncertain
In multi-roller inking system, the interval arrangement of soft and hard ink rollers is for (D).
A. easy installation B. arrangement needs
C. prevention of error replying and reflecting D. good contacting
The distortion of the rubber roller is caused by (B).
A. roller weight B. printing pressure C. printing speed D. the rolling of rollers
In multi-roller inking system, the ink layer away from the ink roller of the printing plate is (A) than that of the ink roller near the plate.
A. larger B. smaller C. uncertain D. irrelevant
(D) is not the necessary condition for the emulsification of ink.
A. The fountain solution and ink do not mix together.
B. Ink and fountain solution contact during printing.
C. There is extrusion between ink and fountain solution.
D. There is surfactant in the fountain solution.
The zero point of the press refers to (A).
A. the point where the transfer gripper grips the paper
B. the point where the transfer gripper and impression cylinder contacts
C. the point where the transfer gripper releases the paper
D. the point where the impression cylinder and delivery cylinder contacts
The three primary colors of pigments refer to the three colors of (C).
A. red, green, blue B. red, yellow, blue
C. pinkish red, yellow, cyan D. red, green, bluish violet
Which of the following is not true (A).
A. Seen afar, the printed graphic is continuous, so it is a kind of continuous graphic.
B. The smallest unit of continuous graphic is the dot.
C. The color range of the printed graphic is smaller than that shown by the computer screen.
D. If there is more printing pressure, the enlargement rate of the dots of the printed graphic will also increase.
Which of the following about the ink vibrator of the press in not true (A).
A. The axial play of the ink vibrator is driven by cam-linkage mechanism whereas the circumferential rotation is driven by friction.
B. For the ink vibrator of general press, the cam-linkage mechanism can be adjusted with the maximum being 2.5-3cm.
C. The cam-linkage mechanism of the ink vibrator helps to remove the malfunction of ghosting in printing.
D. The starting point for the cam-linkage mechanism of the ink vibrator is commonly at the neutral position of the printing plate roller. This makes inking more even on the printing plate.
Which of the following about the adjustment of the drying of ink in printing is right (D).
A. The adjustment of the drying mainly refers to whether dryer is added into ink.
B. The effects of adding red dryer and white dryer are the same.
C. In four-color printing, dryer could be added to adjust the dryness of the ink.
D. For wet overprinting, it is better not to add much dryer to prevent the viscosity of ink from impacting the overprinting of ink.
E. After the dryer is added, the viscosity of ink will increase greatly.
Which of the following is not true about the function of ethyl alcohol in ethyl alcohol fountain solution (C).
A. Ethyl alcohol is a kind of surfactant, which can reduce the surface intensity of fountain solution, conducive to the spreading to other non-printing areas.
B. The temperature of the printing plate surface could be lowered by the evaporation of ethyl alcohol.
C. Ethyl alcohol is a kind of alcohol. Compared with other surfactants, it can greatly reduce the surface tension of water and the emulsification of ink.
D. The content of ethyl alcohol must be controlled as it is not the higher, the better.
The increase of the ink trace of press will lead to (B).
A. The sensitivity of supplying ink on printing plate will be better.
B. The ink layer will be more evenly distributed on printing plate.
C. The ink volume of the ink trace when being printed normally will increase, in other words, the difference of the thickness of ink layer will increase.
D. The press will be more unsuitable for the printing of presswork of dot graphics.
The color sequence of the four-color press during printing is: black-pinkish red-cyan-yellow. Then which of the following is right (C).
A. The image of presswork is mainly a portrait.
B. The viscosity sequence of the four colors during printing is: yellow> cyan>pinkish red> black
C. During printing, the yellow ink is placed at last as the yellow plate has the largest size, and yellow ink has the largest transparency and lowest viscosity.
D. For convenient operations during printing.
What is the order of preferential adsorption (water affinity) of the following (C).
A. chromium> iron> copper> zinc> aluminum> nickel
B. aluminum> iron> copper> zinc> chromium> nickel
C. chromium> iron> zinc> aluminum> nickel> copper
D. chromium> nickel > aluminum> zinc> iron> copper
There are two kinds of rubber sheeting that are commonly used. They are (A).
A. common rubber sheeting and air rubber sheeting
B. hard rubber sheeting and soft rubber sheeting
C. common rubber sheeting and rubber sheeting for special use
D. black-and-white rubber sheeting and colorful rubber sheeting.
(B) are the criteria for determining the ink qualities of the three primary colors.
A. hue, brightness, and saturability
B. coloring efficiency, greyishness, and chromatic error
C. liquidity, light resistance, and chemical stability
D. primary colors, complementary colors, and secondary colors
In offset litho printing, continuous tones are represented by (A).
A. halftone dots B. printing ink C. layers
The surface excitation of the printing plate is because of (C).
A. alumina membrane layer B. grits C. inorganic salt layer
The adding of (C) into the printing ink can increase liquidity.
A. viscosity reducer B. oil 0# C. oil 6#
For J2108 three-roller shell, the diameters of rubber roller is (C), printing plate roller is (B), and impression roller (A), respectively; the diameter of their gear pitches are (A).
A. 300 mm B. 299 mm C. 293.5 mm D. 299.5mm
When the malfunction of paper extracting happens in the printing of coated papers, which of the following should be taken (C).
A. add thin Varnish
B. increase the biting force of impression biting and paper receiving biting
C. extract papers from the rubber to reduce pressure
When two axis are far apart, but the drive is required to be accurate, the drive of (C) should be adopted.
A. belt drive B. chain drive C. wheel drive
Offset printing is developed from chromolithography. In 1798, (D) invented chromolithography.
A. Gutenberg B. Wang Zhen C. Bi Sheng D. Senefelder
The drying ways of litho printing ink is mainly (B).
A. penetration B. oxidation film C. volatilization
The axis is 50.20 and the hole is 49.8, then the coordination is (C).
A. clearance fit B. transition fit C. interference fit
The feeding of paper of J2108 belongs to (B).
A. direct paper feeding B. indirect paper feeding C. beyond paper feeding
The juxtaposition of yellow dots and pinkish red dots is presented in the color (A).
A. red B. green C. blue D. black
Without impacting ink liquidity, to reduce the viscosity of ink, (C) should be added into ink.
A. oil 6# B. abherent C. viscosity reducer
The criterion for checking the dot of printing plates is (B).
A. The dots of the printing plates are darker than those of sample plates.
B. The dots of the printing plates are lighter than those of sample plates.
C. The dots of the printing plates are the same with those of sample plates.
(A) is the overprinting of single-color press.
A. the wet over the dry B. the wet over the wet
During printing, some substances lead to emulsification. They are called emulsifiers. Which of the following is not an emulsifier? (C)
A. dielectric B. surfactant C. alkanes D. solid powder
Lithographic press adopts the cylinder packing of (A), which has the largest compression.
A. felting B. refined worsted C. rubber mat D. photographic paper