I want to find a better master to teach me the technology. I mainly want to learn screen printing and hand printing of various substrates.

Chapter 1 Selection of Silk Screen

Silk screen is the basis for screen printing. The quality of the screen directly affects the quality of the screen printing plate. Whether the screen selection is appropriate , directly affects the quality of screen printing. Therefore, the choice of screen is the primary issue for successful screen printing.

1. Types and characteristics of mesh:

Commonly used wire mesh is usually divided into three categories according to materials, including nylon, polyester and stainless steel, while polyester wire mesh is It is divided into three types: ordinary polyester mesh, high tension and low extension polyester mesh and single-sided flattened mesh. A simple diagram can be used for classification as follows:

Wire mesh

Nylon mesh (polyester mesh) Stainless steel mesh

Ordinary polyester mesh has high tension and low tension Extended single-sided flattened wire mesh

Polyester wire mesh

In addition, there are some professional-use wire mesh. Such as: anti-static wire mesh, polyester wire mesh for glass, nylon wire mesh for ceramics, etc. The following is a brief introduction to the advantages and disadvantages of the following five types of wire mesh.

1. Nylon mesh: It is woven from polyurethane fiber (commonly known as nylon) and has the advantages of polyurethane fiber. That is:

A. It has good resilience and high elasticity

B. Excellent wear resistance, suitable for long-run printing

C. The surface is smooth and has good ink transferability

D. Good surface tension characteristics and strong tensile strength

E. It is not easy to generate static electricity and has certain alkali resistance

The shortcomings of nylon mesh are as follows:

A. Poor resistance to ultraviolet rays or strong direct light

B. Poor acid resistance, affected by temperature and humidity, poor dimensional stability

C. High elongation and large tensile deformation affect the accuracy of overprinting

2. Ordinary polyester screen: woven from ordinary polyester fiber. The advantages are:

A. High tensile strength and can withstand high tension

B. It has good wear resistance and can resist the wear of the screen caused by the pigments in the ink and the squeegee during printing.

C. High light resistance under natural room temperature light. Long shelf life

D. Insensitive to climate factors, low hygroscopicity, and strong heat resistance

E. Low elongation and good dimensional stability

F. It has strong chemical resistance and can withstand ordinary acids, but its resistance to ordinary alkali is limited

The shortcomings of ordinary polyester mesh:

The combination with photosensitive emulsions, too Ink resistance and wear resistance are not as good as nylon. Before plate making, the screen needs to be pre-screened (that is, the screen needs to be roughened, degreased and ground)

3. High-tension, low-elongation polyester screen: woven from high-tension polyester fiber. In addition to the advantages of ordinary polyester wire mesh, its outstanding advantages are:

A. Its structure is more stable, the tension stability is high after stretching the web, and the precision stability is excellent in long-term printing operations.

B． It can withstand high tension and has low elongation, improving the accuracy of overprinting

C. When printing, the screen distance is small, and the screen and ink peel well

D. Long service life, strong mechanical and chemical resistance

4. Single-sided flattened wire mesh: woven from polyester fiber.

It presses the polyester mesh through a pad pressure roller and a rubber roller to flatten one side of the wire mesh. Therefore, the thickness of this kind of screen is reduced by 25%, and the opening area is also slightly reduced. When other processes are the same, the thickness of the printing ink layer is reduced, which is more conducive to the curing of UV ink. Therefore, it is suitable for UV solid ink, so it is also called UV screen. Its outstanding advantages are:

A. It can save about 35% of UV ink

B. The pressing surface is on the ink surface. When printing, the scraper is smoother when scraping on the flat screen. Cool, the stencil has a long service life.

C. The printing has high definition and good dimensional stability, and can print high-quality products.

5. Stainless steel wire mesh: woven from stainless steel wire, with the following characteristics:

A. High tension, low elongation, excellent screen stability

B. High tensile strength and good ink resistance

C. The wire diameter is thin, the aperture is large and the wire diameter opening is quite uniform, and the printing accuracy is high

D. Potential resistance, good chemical resistance, abrasion resistance, and moisture resistance

Disadvantages of stainless steel mesh: easily broken by external force, small rebound, expensive and difficult to place.

2. The physics of the screen and the performance requirements for selecting the screen:

1. In any screen printing application, the extension characteristics of the screen are crucial. Different extension characteristics, even Even though they are made of the same material, they will also have different screen strength, screen stability and other properties. There are also different printing effects. Therefore, the extension characteristics of the screen determine the strength, stability, stretching method and printing quality of the screen. The extension characteristics of the screen directly affect the following usage conditions:

___The ultimate tension of the screen, the registration and dimensional stability of the printed image

____The size of the screen pitch and The separation behavior of the screen and the substrate at low screen pitch

____The adaptability of the object to be printed, especially when the substrate has an uneven or irregular surface

2. Select the performance requirements of the screen

A. Select the extension characteristics of the screen suitable for the printing parameter requirements

B. The wire diameter should be uniform, the mesh thickness should be consistent, and the opening should be uniform and square.

C has good or good bonding force with photosensitive emulsion

D has high tensile strength, good resilience and strong abrasion resistance

F stable Good resistance to temperature and humidity

G Wire mesh with good resistance to chemical solvents and chemicals

3. Main technical parameters of the wire mesh:

1. Mesh number: refers to the number of meshes per centimeter or per inch of length

1 mesh/inch = 2.54 mesh/cm

2. Wire diameter is the woven wire mesh The diameter of the wire, which is the value measured by the production factory on the projection plane of the wire mesh.

Usually expressed by d, the unit is: micron

For example: 1 20-34 means the mesh number is 120d=34u

120- 31 means the mesh number is 120d=31u

120-40 means the mesh number is 120d=40u

It can be seen that the wire mesh can be divided into different grades according to the thickness of the wire diameter, and there are different opinions on the grade terms:

For example: Current terminology Old terminology

120-31 120S

120-34 120T

120-40 120HD

120-27 150SL

The characteristics of wire mesh with the same mesh number and different wire diameters are compared in the following table:

Specifications Features

Code Name Wire Diameter Opening Width Width Width Width Strength

SL Ultra-thin type thinnest largest thinnest lowest

S thin type thin large thin low

T standard type medium medium medium medium medium

HD Thick Type Thick Small Thick High

3. Opening size (hole width): refers to the space measured between two adjacent radial lines (or weft lines) of the wire mesh, usually W Represented in microns.

The screen opening determines the maximum size of the particles in the screen printing ink. In order to achieve full ink penetration, the average particle size of the ink must be less than 1/3 of the mesh.

Screen openings affect the following points:

_____The reproducibility of line or dot printing

_____The ink permeability of the ink

_____The thickness of the printing ink layer

4. Open area (also called open area percentage)

A screen with an open area of ??35%: refers to The opening area per unit area is 35%. The area covered by the wire diameter, closed, and impermeable to ink is 65%. The open area can be used to calculate the change in the theoretical ink volume

5. Silk screen thickness: refers to the surface of the screen to vertical distance from the lower surface. Usually represented by D, the unit is micrometer. It affects the ink passing performance of the screen and the ink amount of the screen. Under the same conditions of mesh number and opening, the thicker the mesh, the less conducive it is to the penetration of ink.

6. Weaving structure: refers to the weaving method of the wire mesh. In terms of weaving methods, it is often divided into: plain weave (indicated by PW

) and twill weave (indicated by TW)

Plain weave is composed of radial threads and weft threads alternately pressed one by one. Root braided, its structure is 1:1 form.

Twill weave is composed of radial threads and weft threads alternating in a ratio of 1:2 or 2:2 or 3:3.

The advantages of plain weave: small contact surface with the substrate, good ink permeability and ink fluidity. The printing quality is high, and the mesh number is generally below 350 mesh/inch.

Twill weave is generally above 350 mesh/inch, with small mesh aperture, thick mesh, poor ink permeability, and large contact surface with the substrate, which affects the fluidity of the ink. Therefore, under the same mesh number, printing The quality is not as good as plain weave.

7. The color of the screen. It is very important to use high-quality, high-definition screen printing.

Usually the colors of the screen are: white is represented by W, yellow is represented by Y

When the white screen is exposed, it will produce reflection and diffuse reflection, causing the distinction between graphics and text. The efficiency and clarity are reduced, and in severe cases, fine lines will not be developed at all.

When choosing a yellow screen, only the yellow color is reflected and has no effect on the photosensitive film layer. It can produce clear images and fine-diameter layers, and can produce high-definition mesh plates. Of course, the exposure time of the yellow screen is about 75% longer than that of the corresponding white screen.

8. The maximum tension of the screen: refers to the maximum tension that the screen can resist. Beyond this pulling force, the wire mesh will break or deform from elastic to plastic, losing its elasticity. Therefore, when stretching the mesh, the tension must not exceed the maximum tension of the mesh

9. Description of the mesh type.

When using wire mesh, we often find a row of words on the edge of the wire mesh. What does it mean? As shown below:

Example: SEFAR ___________ Manufacturer brand

PET.1000 ___________ Material, model

140-34 ___________ Wire mesh mesh 140/c m and Mesh diameter 34 u

Y ___________ color is yellow

PW ___________ weaving method is plain weave

OSC ___________ flat front

Four . Factors that must be considered when choosing a screen:

To achieve the purpose of screen printing, the choice of screen is not determined by a single factor, but must be considered comprehensively. Usually the following four factors need to be considered.

1. Image resolution: The finer the wire diameter, the higher the mesh number, the higher the resolution. The thicker the wire diameter and the lower the mesh number, the lower the resolution. However, the higher the mesh number, the better. If it is too high, the ink output caused by screen printing will be insufficient, resulting in incomplete or damaged imprints. At the same time, under the same mesh number, attention should be paid to the influence of wire diameter. The width or dot diameter of the finest lines that can be reproduced by the two specifications of wire mesh is: Lgt; 2d w, d is the wire diameter, and W is the opening. Width, when dgt;W, the opening area of ??the screen is small, which affects the fluidity of the ink, causing the threads or dots to become jagged or the imprints are incomplete or damaged, and the mesh number of the screen is too high, which will cause the printing results to be the same as those of the screen. Same phenomenon.

Generally speaking, a screen with openings larger than the diameter of the mesh can reproduce a higher resolution than a screen with openings smaller than the diameter of the mesh. Therefore, you should pay attention to the following points when selecting a screen;

A. The larger the mesh number/wire diameter value, the better

B. The smaller the contact area between the printing surface and the substrate, the better

C. In order to meet the resolution requirements, the wire diameter and the opening width of the screen need to meet a certain relationship

D. In order to meet the printing requirements, the relationship between the wire diameter and the ultimate tension needs to be considered

2. Ink layer thickness and covering rate If you want thick ink and good covering rate, you should choose a thick mesh with large holes (i.e. HD level)

3. According to the substrate Choose the screen material according to the surface condition: use a nylon screen with good elasticity for curved or uneven surfaces; use a screen with a large amount of ink for a highly absorptive surface; use a high-tension screen for a smooth surface; use a low-mesh screen for a rough surface. Count the wire mesh; the insulating surface should use anti-static wire mesh, etc.

4. Ink performance requirements: Select the appropriate ink screen according to the ink performance.

5. Storage conditions for wire mesh:

Dry at room temperature, avoid direct exposure to ultraviolet rays or strong light, and place flat on a smooth surface.

Screen printing technology?

2011-9-19 19:28 Questioner: Drunk Xiao Zhuge | Number of views: 6535 times

Let me help him answer

The input content has been When the length limit is reached, you can also enter 9999 words. Insert pictures, delete pictures, insert maps, delete maps, insert videos, video maps, and answer to get 2 experience points. If the answer is selected as a satisfactory answer, the experience and wealth values ??will be increased simultaneously

References: Anonymous answer Submit answer Cancel

Answer ***2 items

2012-3-14 21:51 johnyoto | Level 2

Chapter 1 Screen selection

Silk screen is the basis for screen printing. The quality of screen directly affects the quality of screen printing. Whether the screen selection is appropriate directly affects the quality of screen printing. Therefore, the choice of screen is the primary issue for successful screen printing.

1. Types and characteristics of mesh:

Commonly used wire mesh is usually divided into three categories according to materials, including nylon, polyester and stainless steel, while polyester wire mesh is It is divided into three types: ordinary polyester mesh, high tension and low extension polyester mesh and single-sided flattened mesh. A simple diagram can be used for classification as follows:

Wire mesh

Nylon mesh (polyester mesh) Stainless steel mesh

Ordinary polyester mesh has high tension and low tension Extended single-sided flattened wire mesh

Polyester wire mesh

In addition, there are some professional-use wire mesh. Such as: anti-static wire mesh, polyester wire mesh for glass, nylon wire mesh for ceramics, etc. The following is a brief introduction to the advantages and disadvantages of the following five types of wire mesh.

1. Nylon mesh: It is woven from polyurethane fiber (commonly known as nylon) and has the advantages of polyurethane fiber. That is:

A. It has good resilience and high elasticity

B. Excellent wear resistance, suitable for long-run printing

C. The surface is smooth and has good ink transferability

D. Good surface tension characteristics and strong tensile strength

E. It is not easy to generate static electricity and has certain alkali resistance

The shortcomings of nylon mesh are as follows:

A. Poor resistance to ultraviolet rays or strong direct light

B. Poor acid resistance, affected by temperature and humidity, poor dimensional stability

C. High elongation and large tensile deformation affect the accuracy of overprinting

2. Ordinary polyester screen: woven from ordinary polyester fiber. The advantages are:

A. High tensile strength and can withstand high tension

B. It has good wear resistance and can resist the wear of the screen caused by the pigments in the ink and the squeegee during printing.

C. High light resistance under natural room temperature light. Long shelf life

D. Insensitive to climate factors, low hygroscopicity, and strong heat resistance

E. Low elongation and good dimensional stability

F. It has strong chemical resistance and can withstand ordinary acids, but its resistance to ordinary alkali is limited

The shortcomings of ordinary polyester mesh:

The combination with photosensitive emulsions, too Ink resistance and wear resistance are not as good as nylon. Before plate making, the screen needs to be pre-screened (that is, the screen needs to be roughened, degreased and ground)

3. High-tension, low-elongation polyester screen: woven from high-tension polyester fiber.

In addition to the advantages of ordinary polyester wire mesh, its outstanding advantages are:

A. Its structure is more stable, the tension stability is high after stretching the web, and the precision stability is excellent in long-term printing operations.

B. It can withstand high tension and has low elongation, improving the accuracy of overprinting

C. When printing, the screen distance is small, and the screen and ink peel well

D. Long service life, strong mechanical and chemical resistance

4. Single-sided flattened wire mesh: woven from polyester fiber. It presses the polyester mesh through a pad pressure roller and a rubber roller to flatten one side of the wire mesh. Therefore, the thickness of this kind of screen is reduced by 25%, and the opening area is also slightly reduced. When other processes are the same, the thickness of the printing ink layer is reduced, which is more conducive to the curing of UV ink. Therefore, it is suitable for UV solid ink, so it is also called UV screen. Its outstanding advantages are:

A. It can save about 35% of UV ink

B. The pressing surface is on the ink surface. When printing, the scraper is smoother when scraping on the flat screen. Cool, the stencil has a long service life.

C. The printing has high definition and good dimensional stability, and can print high-quality products.

5. Stainless steel wire mesh: woven from stainless steel wire, with the following characteristics:

A. High tension, low elongation, excellent screen stability

B. High tensile strength and good ink resistance

C. The wire diameter is thin, the aperture is large and the wire diameter opening is quite uniform, and the printing accuracy is high

D. Potential resistance, good chemical resistance, abrasion resistance, and moisture resistance

Disadvantages of stainless steel mesh: easily broken by external force, small rebound, expensive and difficult to place.

2. The physics of the screen and the performance requirements for selecting the screen:

1. In any screen printing application, the extension characteristics of the screen are crucial. Different extension characteristics, even Even though they are made of the same material, they will also have different screen strength, screen stability and other properties. There are also different printing effects. Therefore, the extension characteristics of the screen determine the strength, stability, stretching method and printing quality of the screen. The extension characteristics of the screen directly affect the following usage conditions:

___The ultimate tension of the screen, the registration and dimensional stability of the printed image

____The size of the screen pitch and The separation behavior of the screen and the substrate at low screen pitch

____The adaptability of the object to be printed, especially when the substrate has an uneven or irregular surface

2. Select the performance requirements of the screen

A. Select the extension characteristics of the screen suitable for the printing parameter requirements

B. The wire diameter should be uniform, the mesh thickness should be consistent, and the opening should be uniform and square.

C has good or good bonding force with photosensitive emulsion

D has high tensile strength, good resilience and strong abrasion resistance

F stable Good resistance to temperature and humidity

G Wire mesh with good resistance to chemical solvents and chemicals

3. Main technical parameters of the wire mesh:

1. Mesh number: refers to the number of meshes per centimeter or per inch of length

1 mesh/inch = 2.54 mesh/cm

2. Wire diameter is the woven wire mesh The diameter of the wire, which is the value measured by the production factory on the projection plane of the wire mesh.

Usually expressed by d, the unit is: micron

For example: 1 20-34 means the mesh number is 120d=34u

120- 31 means the mesh number is 120d=31u

120-40 means the mesh number is 120d=40u

It can be seen that the wire mesh can be divided into different grades according to the thickness of the wire diameter, and there are different opinions on the grade terms:

For example: Current terminology Old terminology

120-31 120S

120-34 120T

120-40 120HD

120-27 150SL

The characteristics of wire mesh with the same mesh number and different wire diameters are compared in the following table:

Specifications Features

Code Name Wire Diameter Opening Width Width Width Width Strength

SL Ultra-thin type thinnest largest thinnest lowest

S thin type thin large thin low

T standard type medium medium medium medium medium

HD Thick Type Thick Small Thick High

3. Opening size (hole width): refers to the space measured between two adjacent radial lines (or weft lines) of the wire mesh, usually W Represented in microns.

The screen opening determines the maximum size of the particles in the screen printing ink. In order to achieve full ink penetration, the average particle size of the ink must be less than 1/3 of the mesh.

Screen openings affect the following points:

_____The reproducibility of line or dot printing

_____The ink permeability of the ink

_____The thickness of the printing ink layer

4. Open area (also called open area percentage)

A screen with an open area of ??35%: refers to The opening area per unit area is 35%. The area covered by the wire diameter, closed, and impermeable to ink is 65%. The open area can be used to calculate the change in the theoretical ink volume

5. Silk screen thickness: refers to the surface of the screen to vertical distance from the lower surface. Usually represented by D, the unit is micrometer. It affects the ink passing performance of the screen and the ink amount of the screen. Under the same conditions of mesh number and opening, the thicker the mesh, the less conducive it is to the penetration of ink.

6. Weaving structure: refers to the weaving method of the wire mesh. In terms of weaving methods, it is often divided into: plain weave (indicated by PW

) and twill weave (indicated by TW)

Plain weave is composed of radial threads and weft threads alternately pressed one by one. Root braided, its structure is 1:1 form.

Twill weave is composed of radial threads and weft threads alternating in a ratio of 1:2 or 2:2 or 3:3.

The advantages of plain weave: small contact surface with the substrate, good ink permeability and ink fluidity. The printing quality is high, and the mesh number is generally below 350 mesh/inch.

Twill weave is generally above 350 mesh/inch, with small mesh aperture, thick mesh, poor ink permeability, and large contact surface with the substrate, which affects the fluidity of the ink. Therefore, under the same mesh number, printing The quality is not as good as plain weave.

7. The color of the screen. It is very important to use high-quality, high-definition screen printing.

Usually the colors of the screen are: white is represented by W, yellow is represented by Y

When the white screen is exposed, it will produce reflection and diffuse reflection, causing the distinction between graphics and text. The efficiency and clarity are reduced, and in severe cases, fine lines will not be developed at all.

When choosing a yellow screen, only the yellow color is reflected and has no effect on the photosensitive film layer. It can produce clear images and fine-diameter layers, and can produce high-definition mesh plates. Of course, the exposure time of the yellow screen is about 75% longer than that of the corresponding white screen.

8. The maximum tension of the screen: refers to the maximum tension that the screen can resist. Beyond this pulling force, the wire mesh will break or deform from elastic to plastic, losing its elasticity. Therefore, when stretching the mesh, the tension must not exceed the maximum tension of the mesh

9. Description of the mesh type.

When using wire mesh, we often find a row of words on the edge of the wire mesh. What does it mean? As shown below:

Example: SEFAR ___________ Manufacturer brand

PET.1000 ___________ Material, model

140-34 ___________ Wire mesh mesh 140/c m and Mesh diameter 34 u

Y ___________ color is yellow

PW ___________ weaving method is plain weave

OSC ___________ flat front

Four . Factors that must be considered when choosing a screen:

To achieve the purpose of screen printing, the choice of screen is not determined by a single factor, but must be considered comprehensively. Usually the following four factors need to be considered.

1. Image resolution: The finer the wire diameter, the higher the mesh number, the higher the resolution. The thicker the wire diameter and the lower the mesh number, the lower the resolution. However, the higher the mesh number, the better. If it is too high, the ink output caused by screen printing will be insufficient, resulting in incomplete or damaged imprints. At the same time, under the same mesh number, attention should be paid to the influence of wire diameter. The width or dot diameter of the finest lines that can be reproduced by the two specifications of wire mesh is: Lgt; 2d w, d is the wire diameter, and W is the opening. Width, when dgt;W, the opening area of ??the screen is small, which affects the fluidity of the ink, causing the threads or dots to become jagged or the imprints are incomplete or damaged, and the mesh number of the screen is too high, which will cause the printing results to be the same as those of the screen. Same phenomenon.

Generally speaking, a screen with openings larger than the diameter of the mesh can reproduce a higher resolution than a screen with openings smaller than the diameter of the mesh. Therefore, you should pay attention to the following points when selecting a screen;

A. The larger the mesh number/wire diameter value, the better

B. The smaller the contact area between the printing surface and the substrate, the better

C. In order to meet the resolution requirements, the wire diameter and the opening width of the screen need to meet a certain relationship

D. In order to meet the printing requirements, the relationship between the wire diameter and the ultimate tension needs to be considered

2. Ink layer thickness and covering rate If you want thick ink and good covering rate, you should choose a thick mesh with large holes (i.e. HD level)

3. According to the substrate Choose the screen material according to the surface condition: use a nylon screen with good elasticity for curved or uneven surfaces; use a screen with a large amount of ink for a highly absorptive surface; use a high-tension screen for a smooth surface; use a low-mesh screen for a rough surface. Count the wire mesh; the insulating surface should use anti-static wire mesh, etc.

4. Ink performance requirements: Select the appropriate ink screen according to the ink performance.

5. Storage conditions for wire mesh:

Dry at room temperature, avoid direct exposure to ultraviolet rays or strong light, and place flat on a smooth surface.

Chapter 2 Screen Frame

Screen frame is one of the important equipment for making screen panels. No matter what kind of mesh is chosen, the loose mesh must be tightened on the screen frame before the screen pattern can be produced. Therefore, the quality of the screen frame directly affects the quality of the screen printing.

1. Types of screen frames: They can be roughly divided into three types: wooden frames, aluminum frames, and steel frames.

1. Wooden frame: The cost is very low and easy to handle. It is usually used in small-size screens for manual printing. However, the wooden frame has low strength, is greatly affected by temperature and humidity, and is not suitable for the requirements. The life of printed matter with high overprinting accuracy is also relatively short.

2. Aluminum frame: It has a small specific gravity and is relatively light. Even a large screen frame is easy to handle. Its significant advantages are: low cost (of course more expensive than a wooden frame), light weight, and a wide range of cross-section options. , can be used to stretch various mesh wires, is rust-resistant and easy to clean. But it is not very resistant to acid and alkali, and is not as strong as steel frame.

3. Steel frame: It has good sturdiness, but is relatively heavy and easy to rust. It requires appropriate treatment (galvanizing or painting) and the cost is relatively high.

2. Conditions for selecting a screen frame:

1. The screen frame must have a certain strength and can withstand certain conditions without deformation during stretching and printing, ensuring precise size of the screen frame. , thereby ensuring the accuracy of plate making and printing.

2. On the premise of ensuring strength, try to choose lighter ones.

3. The adhesive surface between the screen frame and the wire mesh must be rough. The surface of the metal screen frame generally needs to be roughened to ensure a strong bond.

4. It will not deform when exposed to solvents, water and temperature changes.

5. Select appropriate screen frames according to different printing patterns to reduce waste and facilitate operation.

3. Selection and processing of screen frame size:

1. Selection of screen frame size:

Depending on the area to be printed and the type of printing, There should generally be enough space around the perimeter of the printable area.

2. Screen frame processing:

_____ roughening: The metal screen frame with smooth surface must be roughened and polished with sandpaper before use

_____ Treatment: The polished screen frame must be thoroughly degreased with solvent (acetone) before use. Oily cleaning agents must not be used.

______Cleaning of old screen frames: The screen, ink and photosensitive adhesive left behind must be removed from the used screen frames, and the edges must be cleaned to avoid tearing the screen.

Chapter 3: Stretching Nets

1. There are several categories of stretching nets. Here are some commonly used ones:

1. Manual Stretching Nets:

It is a method of fixing the wire mesh on the wooden frame with the help of mesh clamps, nails and mesh glue.

Generally, the tension is relatively low, the tension is uneven, the quality is difficult to ensure, and the cost is low

The process flow is as follows:

Making the screen frame? Selecting the screen? Stretching Net? Driving nails? Trimming excess silk screen? Plate making

2. Mechanical stretching of the web:

Use mechanical force to tighten the wire mesh. When stretching the web, stretch it radially first and then Stretching in the weft direction, and finally stretching the diameter and weft direction alternately to achieve the required tension, so it is more uniform than manual stretching.

The process flow is as follows:

Select the screen frame? Clean the screen frame? Dry? Pre-coat the screen glue? Dry? Select the screen? Stretch the screen

? Apply mesh glue? Dry? Cut the screen and trim it? Apply protective tape? Dry? Production

Mechanical stretching of the mesh is more complicated than manual stretching

3. Air pressure stretching:

It is a method that uses air pressure to drive the cylinder movement of the chuck to tighten the screen, and use adhesive tape to stick the screen and the screen frame together. The process is the same as the mechanical screen stretching method, except that tension is applied. The way is different.

4. The angle of stretching is divided into straight stretching and oblique stretching:

____ Straight stretching: means that the diameter and weft of the wire mesh are at 90 degrees from the edge of the screen frame. horn. Its advantages are: saving material and easy to stretch the net.

____ Oblique stretched mesh: refers to the diameter and weft wires of the wire mesh being at a certain angle with the edge of the screen frame. Its advantages are: it can eliminate or reduce teeth. But it costs more materials.

2. Determination of screen tension:

Screen tension is an important factor affecting screen printing quality. The tension of the wire mesh is measured by a tensiometer. Commonly used tensiometers include millimeter tensiometer and Newton tensiometer.

During the test, the tensiometer is placed on the taut wire mesh, and the weight of the tensiometer itself makes the wire mesh sink.

The degree of sinking is displayed on the table. . This reading is the tension of the screen. The units are m m millimeters or N/CM (newtons/centimeter). The method is as follows: point test:

Test one point in the middle for a small screen, five points for a medium screen, nine points for a large screen

Things to note when measuring tension:

____ In order to avoid measurement errors, the instrument should be checked regularly and adjusted if necessary

____ The minimum distance from the screen frame during measurement is 10 cm

____ For multi-color (color registration) ) printing, all screens should have the same tension

____ The contact axis of the tensiometer contacting the screen must be placed in the direction parallel to the screen

____ both warp and weft The tensions in the directions should be equal, and the maximum error exceeds 1N/CM. If they are not equal

it will cause inaccurate overprinting, uneven thickness of the measured layer, etc.

3. Requirements for stretching the mesh:

1. The tension of the wire mesh must be uniform everywhere on the screen.

2. During the stretching process, the maximum tension must not exceed the ultimate tension of the wire mesh.

3. The screen frame must have sufficient strength, and the tension of the screen plate must be stable during its use period.