The operation and drive of the print cylinder can be either gear-driven using straight or helical-cut gears, or servo-driven.
Gear-driven print cylinders are becoming less common due to new technologies and are more common on older presses. Servo-driven print cylinder presses are now being adopted by most manufacturers due to the advantages they offer. Their use is prevalent in flexographic printing presses and they offer advantages regarding the issue of banding, bouncing and gear marking.
Gear-driven flexographic presses
When flexographic printing presses first came to our industry, they were gear-driven with either a straight or helical cut gear; the latter reduces banging, bouncing and gear marking issues. There can be problems that occur with gears, but there are also advantages like no electrical components to worry about.
The different types of straight and helical cut gears have different uses.
Straight cut gears are more common on narrow and mid web inline presses. These use different methods for advance and retard registration, commonly by moving the impression cylinder.
MPS EB gear-driven press has support rings to reduce bouncing/gear marks
Helical gears are mostly found on CI (central impression) printing presses.
This allows the gear and print cylinder to move for advance and retard, rather than the impression cylinder; if the impression cylinder moves it would move all units at once. Helical gears also offer the advantage of having more contact area and a wider gear, helping to reduce bouncing/gear marking.
The reason why gears can be more of a problem with flexo than gravure or offset is that it’s a raised image and not a smooth, round circumference; even with bearers which can cause bounce and gear marks.
Gear-driven print cylinders
- Worn bearings on the print cylinder
- Worn or damaged gears
- Dirty gears (dried ink)
- Heavy impression setting from anilox to print cylinder can cause bouncing and gear marks
- Heavy impression from plate to impression cylinder can cause bouncing and gear marks
- Improper setting can cause plate wear and damage printing plates
- Requires proper care and preventative maintenance for best results
- Straight cut gears
- Helical gears reduce gear bouncing
Servo-driven print cylinders
The servo-driven press has been around for a while and the technology is becoming more attractive to print machine manufacturing companies.
Servo-driven print cylinders offer many advantages over gear-driven systems. They are reliable and also offer the option of retrofitting, i.e. transforming your old gear-driven press into a servo-driven press.
Benefits:
- Lack of gears on the print cylinder helps reduce bouncing/banding
- Ability to log and record information
- Auto registration
- Consistent registration
- Able to adjust lateral registration along with advance and retard
- Job recall function
- Fewer shafts or gears for drive operation
- Calibrated for specific machine manufacturer’s requirements
All these above-mentioned benefits are why printing machine manufacturers are moving towards this technology.
It is not by any means new – it has been around for many years in the wide web flexo industry and is now becoming more popular in narrow and mid web flexo and combination presses.
Now with reduced bounce in print, automatic registration, and ability to recall jobs, servo-driven print cylinders are a big and welcome change in the printing industry.
Along with the advantages of a servo-driven press, there are other options that can enhance daily use and the company’s experience. The new 5G network and I.O.T. (Internet of Things) gives the servo-driven press new options in monitoring and data analysis to help improve production. When combined with other sensors throughout the press, this provides flexibility in the monitoring solutions of your press.
MPS EF-SYMJET servo-driven flexographic and digital hybrid press
Get in touch
With all the aspects mentioned above, there are many different opinions on both types of printing presses.
For many different reasons, it’s becoming harder to find gear-driven presses these days even though both types have their benefits, but I would say servo presses outperform gear-driven presses.
If you have a topic you would like to know more about or suggestions on any of my snippets, please contact me. You can reach me via LinkedIn or via email k.marsh@mps4u.com.
My other label printing snippets are available here.