|(By Gao Yunsheng Flexo Director of Xi’an Aerospace-Huayang)
This article mainly focus on the different types of CI flexo press and illustrates the advantages and disadvantages of each type.
The CI flexo press includes gear drive type, gear sleeve type, and servo drive type. The three types of CI flexo press has co-existed in the market, but the market share has changed a lot. Currently, the servo drive CI flexo press seems to be more favored by customers in printing industry.
Gear Drive CI Flexo Press
The gear type means printing unit driven by gear and it exists due to the limited cost and servo drive technology.
Similar with all CI flexo press, gear drive CI flexo press is also equipped a central impression drum with all printing units surrounded. Usually, the central drum is fitted with a big gear, which is driven by a motor. Both the print roller and anilox are fitted with their own gear respective at the drive side. The big gear will drive the print roller gear, which will drive the anilox gear. In a word, one motor drives the whole printing unit. The principle is as shown in Figure.
Figure1 Drive Structure of Gear Drive CI Flexo Press
Low manufacturing cost
● Print repeat length is not contentious and limited by the gear pitch (5mm or 10mm) . In most cases, 10mm gear pitch is more durable, but some repeat length range can not be covered.
● Short machine life span: due to the abrasion between gears, the life span of gear drive CI flexo is relatively short.
● The cost for making print roller keeps increasing, especially in European countries.
● Long changeover time, low efficiency.
● Ink bar caused by gear transmission (central drum gear, print roller gear, and anilox gear) . Ink bar depends on the precision of gears.
For above reasons, the market share of gear drive CI flexo press keeps decreasing.
Gear combined sleeve CI Flexo Press
Gear drive CI flexo press comes to exist because of the diversified small jobs, frequent job changeover, and increasing print roller making cost.
Similar to the normal gear drive CI flexo press, the print unit is driven by a single motor.
Gear combined sleeve CI flexo Press has reduced the changeover time and the print roller making cost. For this unique structure, operator only needs to change the print sleeves instead of the print roller. However, it requires different gears when change to different print sleeves.
There are two types of structures:
First type: operator need to remove the print roller(mandrel) from the print unit and install the print sleeves and gears. This structure saves the cost for purchasing new print rollers.
Second type: when print roll is at print-off position, operator rotates the print roller (mandrel) and installs the print sleeves and gears. This structure proves higher efficiency in job changeover than normal gear drive ci flexo press. However, the mechanical structure is very complicated.
The gear combined sleeve CI flexo press is more popular in Europe and America while there is less in China. The main reason is that the price of print roller in China is more competitive than that in other parts of world.
Low manufacturing cost and improved changeover efficiency.
● The gear combined sleeve CI flexo press has overcome the issues of job changeover and print roller making cost, but still with shortcomings.
● The rotation type sleeve installation requires extra gear change space in drive side, which incurs operation risk and requires adding more protection devices.
Servo Drive CI Flexo Press
As the development of printing industry and changes of orders, customers have high requirements in the printing quality and production efficiency. Servo drive technology and reducing sleeve cost meet the demands of the market and servo drive CI flexo press develop very fast than ever.
Servo drive CI flexo press is also equipped a central impression drum with all printing units surrounded. The central impression drum, print roller, anilox roller are all driven independently by servo motors. The moving of print roller and anilox roller are controlled by servo motors as well. In total, one print color is equipped with seven servo motor and the structure is as shown in Figure 2:
Figure 2 Drive structure of servo drive CI flexo press
Long service life, high production efficiency, automatic operation, requires less man power, safe operation.
More imported components, making the manufacturing cost higher than gear drive CI flexo press.
Most importantly, servo drive CI flexo press is featured with following functions:
● Continuous repeat printing
The print roller and anilox rollers are driven independently by servo motor. The print repeat can be set to any value within the specified repeat range. Thanks to this feature, it allows print image micro adjustment based on the stretchness of the printing material.
● One key setup
Driven by servo motor, the printing pressure adjustment and register are controlled automatically. Meanwhile, the printing parameters can be stored in the system. However, both the gear drive CI flexo press and gear combined sleeve CI flexo press require manual operation for the gear match.
● Speed self-adaption control function
During 360°rotation of print roller and anilox roller, the servo drive system allows the machine to record and compare the torque, thus automatically optimizing and matching running speed of each color.
● Fault correction function
During setting of the print repeat and pressure setting, the system will give feedback of motor status and generate the alarm information to avoid the harm to machine and operator incurred by mis-operation.
● Intelligent data management function
Able to collect and record the printing status and job parameters.
● Printing pressure automatic compensation
By optimizing each motor parameters based on its mandrel, the slight vibration of sleeve during high speed running can be eliminated to large extent. The zero servo and torque feedback function is able to achieve the stable printing pressure and automatic pressure compensation.
● Quick register
The principle of register is to match position automatically by phase difference calculation. The register is able to move 360°freely without manual operation. The register operation is associated with pressure control system. During register, the pressure will reduce automatically to avoid any print plate scratching.
● High production efficiency
The simple drive structure make it easier to achieve best match between power and inertia, thus resolving the issues of dynamic balance, vibration, noise, and safety.
To achieve precision running, it requires optimized motor dynamic performance. The motor optimizing means adjusting the differences between instruction speed and feedback speed when the motor is in load. In most circumference, difference or tolerance is controlled a millionth of degree and namely within 0.0018mm. Please refer to Figure 3 and Figure 4.
Figure 3 Motor running trend monitoring before optimization
Figure 4 Motor running trend monitoring after optimization
By comparing three type of CI flexo presses, we will have a clear understanding of CI flexo press. Hope this article is helpful to customers, who become clear about the cons and pros of each type and can choose the right machine.
From above discussion and comparison, the CI flexo press develops in the trend of Intelligent, High speed, high efficiency.
Back to the year 2003, Huayang developed the first gear drive CI flexo press and then developed the gear combined sleeve CI flexo press, and servo drive CI flexo press. Corresponding the demand from market, Huayang has supplied mainly the servo drive CI flexo press to the market and almost stopped gear drive CI flexo press and gear combined sleeve CI flexo press.
In October 2019, Xi’an Aerospace-Huayang has developed a new model CINOVA, whose design speed is 450m/min and print speed is 400m/min. CINOVA is intended for high end market in the world.
CINOVA stands for Intelligent, High speed, high efficiency and will surely bring values to our customers in the world.