Operation Performance and Working Principle of Coating Machine

Operation Performance and Working Principle of Coating Machine

The coating machine is used for the surface coating process production of film, paper, etc. This machine is to coat the rolled substrate with a layer of glue, paint, or ink with a specific function, and then rewind it after drying.
Published: Sep 02, 2022
Operation Performance and Working Principle of Coating Machine

What is a Coating Machine?

The coating machine is used for the surface coating process production of the film, paper, etc. This machine is to coat the rolled substrate with a layer of glue, paint, or ink with specific functions, and then cuts it into slices or rolls it after drying. It adopts a special multi-functional coating head, which can realize various forms of the surface coating. The winding and unwinding of the coating machine are equipped with a full-speed automatic film splicing mechanism, and the PLC program tension closed-loop automatic control.

The coating machine needs to uniformly adhere to glue or ink substances on the surface of aluminum foil, plastic film, or cloth textiles. Which requires a high coating process, not only requires uniform coating height but also can achieve high-speed non-stop roll change to improve production efficiency. The rolled substrate, such as paper, cloth, leather, aluminum foil, plastic film, etc., is coated with a layer of glue, paint, or ink with a specific function, and is dried and rolled up.

The Working Principle of Automatic Coating Machine:

The working principle of the automatic coating machine for screen printing plate making is the same, but its performance varies according to different models and different manufacturers.

The coating mechanism consists of a coating tank and mechanical or pneumatic components that control the angle and pressure of the coating tank. Both ends of the coating mechanism are installed on the vertical support arm of the coating machine, and the coating mechanism is moved up and down. Through the transmission of belts, chains, or cables to coat along the surface of the wire mesh. The transmission mechanism is connected to the servo or frequency conversion motor, which makes it operate smoothly and can precisely control the position of the coating mechanism.

Before coating, load the clean stretched screen from the front of the coating machine, and some models can also load the screen from the side. Among the models designed for large-format screen frames, side loading is more common, because the screen frame is large and bulky, and side loading can reduce the amount of lifting and moving. When the automatic screen coater is running in line with other automatic screen processing equipment, it is more convenient to load the plate from the side.

Regardless of how the screen is loaded, once the screen is in the correct position, the pneumatic or mechanical clamping device closes and locks the screen. For more convenient operation, many models have foot pedals to control the action of the plate clamp, and the operator can free both hands to control the screen plate. After installing the screen, pour the corresponding photosensitive emulsion into the automatic coating machine, and then start coating. According to the functions of the control system and the equipment, the equipment can coat both sides of the wire mesh at the same time.

There are two coating methods, one is to coat the photosensitive emulsion on the screen by multiple wet pressing operations, or the drying process is added after each coating. A machine that quantitatively coats liquid polymer materials such as adhesives or coatings on the surface of materials.

What is Micro Gravure Coating Technology?

Micro gravure coating, the diameter is generally between Φ20mm-Φ50mm, it is a directional, contact coating method. The rotation direction of the micro-coating roller is opposite to the feeding direction of the film, and the film is not pressed by the roller on the roll. Traditional gravure coating methods, whether direct coating or reverse coating, generally have back-pressure rubber rolls and anilox rolls. Since the film is pressed between the rubber roller and the anilox roller, defects such as wrinkles and cracks will likely appear on the coating surface. The contact point of the two rollers will affect the coating quality due to mechanical, air pressure, and other factors. Micro gravure coating, on the other hand, is contact coating, which means that there is no back-pressure rubber roll, so some potential disadvantages due to the pressure of the back-pressure roll are eliminated.

Advantages of Micro Gravure Coating:
  • A thin coating can be applied to thin materials. Since there is no back pressure roller, there are no defects such as offset printing and wrinkles on the coated surface.
  • Since there is no back pressure roller, the edge of the film can also be coated with glue, without worrying that the glue will be applied to the back pressure roller and affect the coating.
  • Due to the light contact of the scraper with the anilox roll, the wear of the scraper and the anilox roll is small.
  • The gravure roll is small in diameter and light in weight, and can be coated with different coating amounts, it is more convenient to replace the gravure roll.
  • Reverse coating can obtain a relatively flat coating, and the coating amount is evenly distributed.
Disadvantages of Micro Gravure Coating:
  • The glue storage tank for micro gravure coating needs to be kept overflowing during coating. The micro gravure roller only contacts with the overflowing liquid phase, so the glue in the glue storage tank cannot be fully utilized and cannot be recycled. Therefore, a certain amount of glue is wasted.
  • If the gravure roller is not cleaned after use, it will easily cause the gravure roller to rust and it will be difficult to remove rust.
  • Since the glue in the glue storage tank is exposed to the air during coating, dust, and particles in the air easily fall into the glue storage tank during coating, which will have a certain impact on the coating quality.
  • The glue supply system of micro gravure coating is more complicated, it is difficult to clean and disassemble, and it takes a long time.
Application of Micro Gravure Coating:

Light-shielding films, various optical films, materials for lithium batteries, various composite tapes, and protective films.

What is Comma Roll Coating Technology?

Comma roll coating features a combination of blade and roll blade. The influence of the glue thickness is smaller than that of the blade scraper, the coating thickness is easy to adjust, and high viscosity glue can be applied. When the width is larger, it can be adjusted horizontally.

Advantages of Comma Roll Coating Technology:
  • The strength and hardness of the comma scraper are high, and the straightness error of the cutting edge is small. The position of the scraper can be adjusted and controlled by a pneumatic fine-tuning mechanism, and the coating amount control and scraping precision are high.
  • A thicker coating can be applied. When coating, the glue flows from top to bottom between the blade and the material film, so the glue can be fully used, and there is no waste of glue.
Disadvantages of the Comma Roll Coating Technology:
  • The coating quality of comma roller coating is closely related to the operation of each component unit, especially the transmission ratio between the drive motor and the rotating pressure roller is difficult to adjust and master. Which often results in uneven coating and is prone to horizontal or vertical irregularities. Stripes, when coating, the glue is easy to flow out from the gap between the baffle and the transmission roller, the sealing is not complete, and when coating, it is necessary to manually stir the glue in the glue tank to ensure the uniformity of the glue distributed.
Application of Comma Roll Coating:

Various optical films, protective films, film films, and matte flexible packaging films.

What is Slot-Die Coating Technology?

Slot Die Coating Machine is a high-precision coating method. The coating glue is pressed from the storage to the nozzle through the supply pipeline, and the glue is sprayed from the nozzle, to be transferred to the coated substrate.

Advantages of Slot-Die Coating Technology:
  • The coating effect is good, the coating amount is flexibly controlled by the micro-adjustment of the coating scraper, and the coating precision is high.
  • It can coat in discontinuous mode, and the coating range can be adjusted freely, no baffle is needed, and there will be no stains caused by different edge thicknesses.
  • It is easier to clean and disassemble.
  • Helps to maintain a high level of cleanliness, and the channel for the overall flow of glue can be sealed to prevent the entry of other contaminants.
Disadvantages of Slot-Die Coating Technology:
  • Part of the structure of the entire Slot-die coating head is more complex, requiring higher processing accuracy of the cots, coating rollers, traction rollers, and scrapers, so the cost is higher than other coating methods.
  • Due to the high precision, it is difficult to use and operate.
Published by Sep 02, 2022 Source :kknews

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