Screen printing 150 questions (19-27)

â–¼19. What materials are used to make the frame and what are the characteristics of these materials?

The materials used to make the frame include wood, hollow aluminum profiles, cast aluminum molding frames, and steel materials. The most commonly used is the frame made of aluminum. However, all kinds of network frames have their own characteristics. When selecting, different network frames can be selected according to different situations.

The wooden net frame has the characteristics of simple production, light weight, convenient operation, low price, and simple stretching method. This frame is suitable for manual printing. However, the wooden frame of this wooden material is poor in solvent resistance and water resistance, and is easily deformed after being immersed in water, which affects the printing accuracy. This kind of mesh frame was commonly used before and it is rarely used nowadays.

Hollow aluminum profile net frame and cast aluminum molding net frame have the features of easy operation, high strength of net frame, firm deformation, high resistance to solvents and water resistance, and beautiful appearance.

Suitable for mechanical printing and manual printing.

The steel net frame has the characteristics of firmness, high strength, and good resistance to solvents and water, but it has the disadvantages of being bulky and inconvenient to operate, so the scope of use is very small.

â–¼20. What are the conditions for selecting a frame?

The network frame is one of the important materials for making screen printing plates. The appropriateness of the selection of the frame has a direct influence on the plate making quality and on the printing quality. In order to ensure the plate making, printing quality and other requirements can be selected based on the following conditions.

1 The frame must have some strength. Because when the net is stretched, the wire mesh has a certain tension and pressure on the net frame. This requires the frame to withstand pressure, can not be deformed, to maintain the frame size accuracy.

2 Under the condition of ensuring the strength, the net frame should be chosen as light as possible for easy operation and use.

3 The mesh frame and screen bonding surface must have a certain degree of roughness in order to strengthen the adhesion of the screen and the frame.

4 The sturdiness of the frame. In the use of the network frame, it is often in contact with water and solvent, and is affected by changes in temperature. This requires that the screen frame is not skewed, so as to ensure the repeated use of the frame. This will reduce waste and reduce costs.

5 The network frame with different specifications should be configured in production. When using, the appropriate frame can be determined according to the size of the printing size, which can be less wasteful and easy to operate.

â–¼21. What are the main specifications of the aluminum frame?

From the foregoing, we can see that the screen mesh frame made of hollow aluminum profiles has features such as light weight, stable size, beautiful appearance, and easy operation.

â–¼22. What are the physical performance indicators of common frame materials?

The most commonly used screen frame for screen printing is an aluminum mesh frame, followed by a wooden mesh frame and a steel mesh frame. The main physical performance indicators of these types of frames are as follows:

1 Elasticity coefficient in Newtons/cm. The coefficient of elasticity of wood material is 0.12×10 7 Newtons/cm, aluminum is 0.75×10 7 Newtons/cm, and the elastic coefficient of steel is 2.1×10 7th power. Newton/cm.

2 moment of inertia, expressed in units of centimeters. When the cross-section shape of the frame material is a hollow rectangle (frame size is 5×4 cm, wall thickness is 2.5 mm), the moment of inertia of aluminum material and the moment of inertia of steel material are 15.088 cm, and the wooden frame cross section is 15.088 cm. When the shape is solid rectangle (5 x 4 cm), the moment of inertia is 41.667 cm.

3 Density, expressed in grams per cubic centimeter. The wood density is 0.9 g/cm3, the steel density is 7.8 g/cm3, and the aluminum density is 2.7 g/cm3.

4 coefficient of thermal expansion (10th power/°C). Aluminum has a coefficient of thermal expansion of 2.410 for five cold power/°C, a coefficient of thermal expansion for steel is 1.2 10 for a fifth power/°C, and a coefficient of thermal expansion for wood is 3.0 10 for a fifth power/°C.

â–¼23. What are the main characteristics of silk screen printing materials?

Mesh screens commonly used in screen printing are nylon mesh, nylon mesh, polyester mesh, and stainless steel mesh. The main features of various screens are the following.

1 Tensile strength [g (g)/D (diameter)] gauze is 3.7-4.1 g (g)/D diameter), nylon gauze is 4.5-5.8 g (g)/D (diameter) ), Polyester mesh 4.3-5.5g (grams) / D (diameter), stainless steel mesh 1.5g (grams) / D (diameter).

2 Dry-wet strength ratio (%) The net weight is 92% to 100%, nylon mesh is 89% to 90%, polyester mesh is 100%, and stainless steel mesh is 100%.

3 Nodule Strength [g (grams)/D (diameter)] Netting is 2.9 g (grams)/D (diameter), nylon mesh is 4.5-5.4 g (g)/D (diameter), Polyester mesh is 3.4-4.4g (g)/D (diameter).

4 tensile elongation (%) 8-22% of netting, nylon screen 26-32%, polyester screen 16"30%, stainless steel screen 38%.

5 Dry-wet elongation ratio (%) A mesh thickness of 134% for nylon 120, 115" 122% for nylon mesh, 100% for polyester mesh, and 100% for stainless steel mesh.
6 Tensile recovery rate (%, calculated with 3% extension) The stencil net is 80-aluminum material moment of inertia and steel material has a 15.88-centimeter square of inertial moment, and the cross-section of the wooden net frame has a solid rectangle ( 5 x 4 cm), moment of inertia 41.667 cm 4th power.

7 Density in units of grams per cubic centimeter. The wood density is 0.9 g/cm3, the steel density is 7.8 g/cm3, and the aluminum density is 2.7 g/cm3.

8 Thermal expansion coefficient (10`/°C). The thermal expansion coefficient of the aluminum material is 2.410`/°C, the thermal expansion coefficient of the steel material is 1.2 10′/°C, and the thermal expansion coefficient of the wood material is 3.0 10′/°C.

â–¼24. What are the characteristics of screen printing nylon mesh?

Nylon mesh is made of chemically synthetic fibers and belongs to the polyamide family. Nylon mesh has high strength, abrasion resistance, chemical resistance, water resistance, and elasticity are all better. Because the wire diameter is uniform and the surface is smooth, the ink passability is also excellent. The disadvantage is that the stretchability of the nylon mesh is large. This kind of wire mesh has a reduced tension after stretching for a period of time, which causes the screen printing plate to loosen and the precision to decrease. Therefore, it is not suitable to print circuit boards with high dimensional accuracy.

â–¼25. What are the characteristics of silk screen printing polyester mesh?

Polyester mesh is also made of chemically synthetic fibers and belongs to the polyester family. Polyester mesh screen has the advantages of solvent resistance, high temperature resistance, water resistance, and chemical resistance. Polyester mesh screen has stable physical properties and small stretchability when external pressure is large. The disadvantage is the poor wear resistance compared to nylon mesh. In addition to the advantages of nylon screen printing, polyester screens are also suitable for printed circuit boards that require high dimensional accuracy.

â–¼26 . What are the characteristics of stainless steel screen printing screens?

Stainless steel mesh is made of stainless steel. Stainless steel wire mesh is characterized by good wear resistance, high strength, and low mechanical elongation. Due to the fine wire diameter, the ink has good passability; the mechanical and chemical properties of the wire mesh are stable, and the dimensional accuracy is stable. The lack of flexibility is poor, and the price is more expensive. After the screen is stretched, it cannot be restored to its original shape. Stainless steel wire mesh is suitable for high-precision printing such as circuit boards and integrated circuits.

â–¼27. How to choose a screen?

Silk screen is the basis of screen printing. Choosing the right screen is an indispensable part. Since the screen printing has a wide range of applications, the factors related to it are numerous. When selecting the screen, it is necessary to select different screens according to the specific conditions and printing requirements. Generally, when selecting the screen, it can be considered from the following different perspectives.

1 Select the screen according to the type of substrate. When selected, the fabrics, paper products, glass, ceramics, metals, plastics, wood products, and electronic products are selected and used.

2 According to the nature of the ink selection screen different inks have different adaptation characteristics. Therefore, when selecting the screen, the ink drying time, color brilliance, and the ink absorption ability of the substrate should be taken into account.

3 According to the wire mesh material and the performance of the selected wire mesh, the mesh material itself and physical properties should be taken into consideration, and the corresponding wire meshes should be selected according to different suitability.

4 Select the screen according to the printing index. When selecting, check the printing speed, the printing pressure, the printing plate's resistance to printing, and the absorption capacity of the substrate.