Tech Corner with Héctor
by Héctor Quintero
Anatol’s VOLT series of all-electric automatic screen printing presses are set apart from other machines on the market by a motorized movement system that does not require the use of pneumatic components or an air compressor. Therefore, the operations necessary for screen printing on different textile products are entirely electrically controlled.
There are currently two types of motors used on the VOLT series: conventional (alternating current, or AC) electric motors and servo motors. Both types of motors have their own unique features and benefits, so choosing the right type of motor will depend on the specific needs of the application in which the machine will be used.
How Conventional (AC) Electric Motors Work
In conventional electric motors, electric current generates a magnetic field, which in turn generates motion. These motors are suitable for applications that require constant speed and force. However, conventional electric motors are not as well suited as servos for applications that require high precision speed and position control.
On a VOLT with electric motors in the print heads, the stroke length (the distance the flood bar and squeegee travel, based on the size of the image you are printing) is determined by proximity sensors indicating the start and end of the stroke. The proximity sensors must be moved by hand to the desired front and rear stroke limit positions, and the stroke length must be set individually for each print head. This mechanism, while offering a high degree of precision, is not capable of as precise movement as servo motors.
The Advantages of Servo Motors
On the other hand, servo motors use a feedback system to precisely control position and speed. These motors are suitable for applications that require high-precision motion control, which means they are well suited to perform repetitive printing operations on textile products, especially jobs that employ highly detailed designs. Additionally, servo motors are also more energy efficient than conventional electric motors, meaning they consume less power and lower operating costs.
On a VOLT with servo motors on the print heads, the start and end of the print stroke are set electronically via the touchscreen control panels found at the end of each print head, or the main touchscreen. There are no proximity sensors that have to be moved by hand, and once the stroke length is set for one print head, it can be copied to all print heads with the touch of a button. This makes job setup easier and faster.
VOLT presses with servo print heads allow you to program squeegee pressure digitally
Because the movement of the squeegee and floor bar is powered by servo motors, the precision is higher compared to conventional electric motor heads, and far in advance of machines that use pneumatic components for print head movement. Not only is the back-and-forth (horizontal) movement of the squeegee servo-driven, but also the up-and-down (vertical, or “chop”) movement.
That means the squeegee pressure for each stroke can be set through the touchscreen control panels, delivering more consistent, repeatable pressure than pneumatic machines are capable of. Servo-driven squeegee pressure ensures the squeegee travels on a perfectly parallel plane to the pallet underneath, so ink deposits are even across the entire image area, resulting in higher quality prints. In summary, not only are servo motors more consistent and precise, they also make the machine more user-friendly and reduce the time needed for job setup.
Making the Right Choice
In conclusion, not only are servo motors more consistent and precise, they also make the machine more user-friendly and reduce the time needed for job setup. Ultimately, choosing the right motor for a VOLT will depend on the specific demands of the typical print job. If high-resolution designs and high-precision motion control are required, a servo motor would be the right choice. On the other hand, if the design only requires constant speed and pressure, a conventional electric motor would be a better choice. In any case, Anatol’s VOLT series automatic screen printing presses, being electrically controlled, offer superior quality by maintaining registration over time.
Héctor Quintero is an electronic engineer with a master’s degree and a doctorate in microelectronics. With more than 15 years of experience, he has participated in various technological projects both in the academic and business fields, developing different software and hardware applications.
Héctor has also dedicated part of his career promoting and teaching electronics and free hardware-based programming. Thanks to his passion for teaching, he has provided hundreds of hours of training to students from Latin America.
He currently belongs to Anatol Equipment’s technical support team, participating in the import, installation and maintenance of various state-of-the-art screen printing equipment in Latin American countries.