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Textile Machines – Rotary Printing Technology

The printing machines are used to print the design on the fabric. There are 3 Types of Printing Machines

  1. Rotary Printing Technology
  2. Flat Belt Printing Technology
  3. Digital Printing

Rotary Printing Technology

Rotary Printing or Rotary Screen Printing is so-called because it uses a cylindrical screen that rotates in a fixed position instead of a flat-screen that is raised and lowered over the same print spot. Rotary presses insert the squeegee inside the tube. These devices are designed for roll-to-roll printing of textiles from narrow to wide-format textiles on cloth.

Rotary Printing TechnologyThrough Rotary Printing the fabric moves directly below the screen at a constant pace between the screen and a roller of steel or rubber effect. (The impression roller performs the same purpose as the pressure bed on a flatbed press.) When the fabric moves through the rotary unit, the device spins at a rate that matches the pace of the movement of the substrate.

The squeegee on a rotary press is in a fixed position with its edge making contact with the screen’s inside surface precisely at the point where the glass, the substratum and the roller of the impression join. Ink is automatically fed into the center of the screen and collects in a wedge-shaped “well” created by the squeegee’s leading side and the inner surface of the screen. Screen motion causes this ink bead to roll, which pushes ink into stencil holes, effectively flooding the screen without having a flood bar. The squeegee then shears the ink as the stencil and substratum come into touch, enabling the ink to be cleanly transferred to the content.
Higher output speeds are obtained by transforming the screen-printing cycle from semi-continuous to continuous than in flatbed printing. Typical speeds for rotary screen printing range from 50-120 yards per minute, depending on the nature of the design and the fabric construction. Rotary screen machines are more lightweight, with the same number of colors in the pattern than flat screen machines. Hence they use less room on the floor of the factory.
The size of the design repeat depends on the diameter of the displays, too with rotary displays. Initially, this was seen as a downside as the first rotary displays were low in diameter. Nonetheless, displays are available in a variety of sizes with today’s equipment and are no longer considered to be limited in nature. The rotary screen machines of today are highly competitive, allow for a rapid pattern change, have few design limitations, and can be used for both continuous and discontinuous patterns.
Estimates suggest that this technique controls about 65% of the worldwide market for printed fabrics. The key drawback of rotary screen printing is that the machine has high fixed costs. Given the clean-up and machine downtime when changing patterns, the machines are generally not profitable for short yardages of widely varying patterns. Flat-screen printing is much more appropriate for high-pile fabrics, as there is only one squeegee transfer with a rotary screen. Nevertheless, rotary machines are used for pile fabrics in carpets and other styles. Most knit fabric is printed using the rotary screen method because during the process it does not stress (pull or stretch) the fabric.

Rotary Printing Machines Parts

Rotary Printing machines consist of the following units,

  1. Fabric Entry Unit
  2. Sucking Device
  3. Fabric Centering Device or Segment roll
  4. Gluing Device
  5. Blanket
  6. Blanket Centering Device
  7. Printing Units or Heads
  8. Magnetic Beams
  9. Color Pump
  10. Washing Device
  11. Conveyer
  12. Conveyer Centering Device
  13. Plaiter
  14. Dryer Chamber
  15. Circulation fans
  16. Gas Burners or Oil heating System
  17. Exhaust Fan

1. Fabric Entry unit:

A fabric entry device is a device that unrolls the fabric from the batcher and moves the tissue to the pad. It is composed of a roller that rotates with the aid of an inverter or drive drove motor. The drive can run in manual and auto mode. There is the selector switch on the entry panel to select the mode. The speed of the motor can be changed in manual mode with the help of a potentiometer which transmits the reference voltage to the drive or inverter. While in Auto mode the unit velocity is synchronized with the compensator velocity of the blanket. The unit’s arm is pushed up or down, using the pneumatic piston.

2. Sucking Device:

The sucking device is used to suck the particles of dust from the fabric and fluff them out. Mostly it has two high-power sucking blowers which start automatically when the blanket is running. Mostly it has two high-velocity motors to suck the blower.

3. Fabric Centering Device and Segment roll:

This unit is built to keep the fabric in the center of the machine and mounted just before the blanket. This unit can work on an electrical system or a pneumatic system.

Segment roll is used to hold the knitting fabric in the blanket’s middle. It has two sensors on both sides which senses the location of the fabric and transmits the signal for the sliding motor to run. It also uses one motor to rotate the segmented roller that is paired with a blanket.

4. Gluing Device:

This tool is used to place the thin glue film on the blanket. It is made up of electromagnetic coils or beams that attract rollers partially sinking into the glue. The pad is in between the magnetic field and the roller. There’s a selector switch that can energize the coil to attract segment desire numbers that depend on the fabric’s width. The magnetic beam is driven from a DC source.

5. Blanket:

It is the machine’s biggest and most important component since the fabric is printed on it. This device has one motor (AC or DC) that rotates the blanket for input and is coupled to the encoder or Resolver. With the aid of an inverter, the speed of the blanket rotation is adjusted. Inverter for the blanket unit is the inverter for the master which transmits the reference speed to all the inverters to synchronize the system. At the near-gluing tool and washing unit, there are two safety limit sensors mounted on both the left and right sides. When the blanket enters and crosses the limits on the side of the color and on the side of the operator, the blanket limit sensor activates which stops the machine and protects against any blanket damage. There is one blanket washing tool that has one motor coupled to the brushing roller and the glue and other printing colors are separated from the blanket.

6. Blanket Centering Device:

There is a centering guide roller to control the blanket movement, which changes its location with the assistance of a guiding motor. This motor is operated by the feeler which senses the location of the blanket and makes the touch, depending on the position, to run the guiding motor clockwise and counterclockwise.

7. Printing Units and Heads:

Print heads are the part of the machine where the screen is placed and used to display on the fabric of the design. Our computers have a range of 12 to 21 colors. Every head is a single color and is a complete unit.

There are two types of open bearing, one being called open bearing and the other being closed bearing. There is a single motor for each unit in Zimmer to operate the computer and one motor for all units in Reggiani. We do have two motors to change the unit as per design: one is the cross repeat motor and the other is the diagonal repeat motor. Both the motors are controlled to change fabric design.

There is a color level sensor that is placed beneath the screen used to operate the color pump. The growing device has a color pump separate from it. Each pump used to pass color to the screen from its color every. Use the pneumatic device, the machine may be moved up and downwards.

8. Magnetic Beam:

There are two types of magnetic beam one being the type of the coil and the other is the type of the pole. It is powered via the DC power supply variable (40 to 90Vdc). As we increase the voltage the magnetic beam attraction power is increased so we have to adjust the voltage according to the fabric quality.

9. Conveyor:

It is used via the dryer chamber to move the fabric from the blanket into the trolley. It consists of a motor and its velocity synchronized with the blanket using a photosensor placed at the end of the blanket. We can also manually run it using the Potentiometer or HMI. A conveyor centering device is available which controls conveyor movement. This centering device operates on a blanket centering device with the same concept.

10. Dryer Chamber:

In our printing presses, there are two types of dryer chamber which are as follows,

  1. The chamber in which natural gas is used for heating.
  2. The chambers in which hot oil is used for the heating.

11. Circulation fan:

Zimmer II machine has 4 circulation fans and Zimmer I has 9 circulation fans and the Reggiani machine has 6 circulation fans. It is used for the diffusion of air inside the room. Every circulation fan has a pressure switch to relay the signal that the fan is operating when the pressure switch is started to make sure that the circulation fans are working properly. These are operated in two (single/double) speed mode. Circulation fan switches the motor from single speed mode to double speed mode in just a few minutes. Circulation fans are helpful to keep the temperature of desire in dryer temperatures. If the fan motors in use are faulty alter it immediately. In each chamber there is one air pressure switch mounted, which gives the signal that the circulating fan throws the air.

12. Exhaust fan :

It is used for chamber emitting gases and moisture. Its speed can be manually controlled at single and double speed. The exhaust fan speed can be adjusted in the type of the screen or the operating panel. Within the Zimmer machine’s exhaust pipe, there is a pressure switch that ensures that the mechanism exhausts in working or not. (Burners and dryer oil heating system should not be turned on until the exhaust runs.)

13. Burner:

Four burners are installed on machine Zimmer II. Each chamber possesses a complete burner unit. Each burner unit consists of the blower motor, gas controlling motor valve, ignition & sensing rods, and flame controller. When the circulation fan & exhaust fan generates the activation signal then the 1st of all the burner’s blower is turned ON and the burner controller is also generated with the signal that all things are right. The ignition transformer ignited after the above cycle, and the burner pilot is lit. When the flame holds the motorized valve comes to its minimum location, and the temperature begins to sustain. Burner units do have the protections, the central gas inlet valve shut OFF in case of any abnormal actions of the burners.

There is an oil heating system at Zimmer I & Reggiani station. Each chamber has a motorized oil valve that is operated by a temperature control unit.

14. Plaiter:

Putting the fabric inside the trolley is common. It has a DC motor on the Zimmer I & Reggiani unit which is powered by DC drive while the inverter-driven AC motor in Zimmer II is used for it and both of them are synchronized with the system using the compensator potentiometer.

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