Seemingly a small cog in the big flexo printing machine wheel - yet the end seals play a vital part in the proper functioning of the chamber doctor blade system. The right end seal solution promotes accurate doctoring results and leak tightness. The benefit therefore is: less cleaning, less machine down time, less ink waste, i.e. true cost and time savings.
Identifying the most suitable sealing concept
So how do you get to the optimal sealing solution? The magic word is custom-designed. The world of flexo printing is manifold: The application environment of narrow web label printing compared to wide web flexible packaging production or coating and converting applications differs considerably and so do the demands on end seals.
First, the parameters of the application are analyzed: Machine brand and model, ink type, printing speed, chamber geometry, substrate, final print product, load factor of the press, all these are important factors for the sealing concept and sealing material choice.
Translating the concept into a tangible sealing solution
Next, we decide on the most suitable production method depending on the material and job lot. The different options available are: water jet cutting, CNC cutting, punching or even injection molding. Choosing the right production method is crucial to achieving smooth sealing surfaces and a neat sealing shape.
Since the Agergaard Company produces in house, we have 100% control about the final outcome. That includes consistent quality controls throughout the production cycle in order to ensure that our customers continuously receive an end seal of reliable quality.
Taking advantage from coatSEAL best practice
No matter what printing application an end seal is required for, if it is a Comexi, Windmöller & Hölscher, Uteco, Schiavi, Fischer & Krecke, Bobst, Gallus, Flexotecnica, Bielloni, Martin, Nilpeter or another press, whether it is equipped with a Tresu, Harris & Bruno, Absolute Engineering or another chamber system, we can work out a compatible alternative sealing solution that suits the individual requirements best.
In doing so, we do not necessarily need to start from scratch - there are a lot of coatSEAL solutions that have proven themselves already and are used at diverse printing shops around the world. Our flexo end seal catalogue gives some inspiration.
|Material||synthetic foam||technical rubber foam||stiff synthetic||impregnated felt (various hardnesses)||rubber (vulcanized)|
|Ink/coating type||all||all; especially solvent||all; especially UV||all; especially water based and UV||all; (Type E: UV/solvent) (Type P: water)|
|Properties||flexibility||high restoring force; flexibility||high shape stability||lubrication reservoir; excellent anti-frictional properties||high wear resistance; strong restoring force|
|Typical application||frequent ink changes; label printing; flexible packaging||label printing; flexible packaging||thin seals; large anilox contact surface; label printing; flexible packaging||long production runs; label printing, flexible packaging; corrugated; tissue||long production runs; label printing, flexible packaging; corrugated|
|Printing speed||moderate (<300 m/min)||medium (<400 m/min)||medium (<400 m/min)||all||all|
High end solution
The Universal material consists of wear resistant rubber, which is suitable for all kinds of printing inks and cleaning agents and performs extremely well also in high speed applications.
Universal end seals are complex designs that are adjusted with highest precision to the chamber geometry and can only be manufactured in a molding process. Therefore this sealing concept is mainly used for high volume serial production.
Masters solvent / High speed
The AIR80 material is a special synthetic with strong chemical resistance. This material performs very well with solvent based inks but is also a feasible option for water based inks.
Thanks to their extremely high restoring force AIR80 seals withstand compression and distortion and thus qualifiy for mechanically demanding applications.
If used for high speed printing, the contact zone with the anilox roller can be coated with a PTFE layer, which reduces friction, diminishes ink residues in the sealing area and extends the seal life time.
Longlife B (black) and Longlife W (white) end seals consist of different felt types, which are treated with a special thermo impregnation. The lubricant which is used for impregnation is food and cosmetic safe, that is why this sealing concept is often used for packaging printing applications.
End seals made of the Longlife material show a remarkably long lifespan, especially in combination with water based inks, and thus keep the chamber leak-proof for a long period. Due to their lack of restoring force, the Longlife seals require a 100% adjustment to the chamber geometry in order to perform optimally.
The LD40 material is synthetic foam with a very high flexibility. Being resistant against all usual printing inks and cleaning agents, it offers an good performance cost ratio. That is why it is often used for applications where the end seal is replaced after a job run.
This material can also be a feasible concept for presses that run at relatively low speed and thus do not wear off the seal heavily.
For applications, of which the exact chamber geometry is not 100% determined, the LD40 represents the ultimate choice because it adapts easily to the chamber outline.
Ideal for UV
The NW material is stiff synthetic foam that is often used when the set up of the chamber doctor blade system requires a rather thin end seal.
While it can be used for all ink systems, it performs especially well in combination with UV inks.