Flexo Graphic Printing
Doctor Chamber Seals. Flexo-Seals. End Seals.
Commonly overlooked as an inconvenient, but necessary consumable item. “Chamber End Seals” it could be said are widely taken for granted.
However these components are vitally important in maintaining extended Doctor Blade life, reduced ink wastage due to leakage, and possibly most important is the elimination of score lines and impression marks made on cylinders and finished print runs.
An enclosed chamber can potentially be a large investment for any organisation and one of the determining factors in its continued and effective operation is the quality and functionality of the chosen End Seals.
Wool Felt Impregnated with lubrication Wax.
A “Felt End Seal” manufactured from high quality wool felt containing minimum 95% wool, provides one of the most effective liquid seal barriers available in the market.
Due to its structure of naturally interlocking hollow fibres, felt can absorb many times its own weight in fluid and retain that fluid within its matrix until it is demanded by another medium.
A good quality felt will not flood, nor leak. It will absorb to its maximum potential then effectively self seal and absorb no more. We can offer impregnated felt seals, using a special thermo-reactive wax that is non-reactive to oil or UV inks, food, skin and ingestion safe.
The priming of the seal helps operation in a number of ways, the most significant being:
- The wax will be released to the surface contact point between the felt seal and the cylinder providing a seamless lubricating impenetrable membrane in which the cylinder is allowed to ride. This lipid seal is the essence of all lubrication systems that involve a felt seal and a rotating shaft.
- Due to the felt already reaching its optimum absorption point during priming, it neither allows ink to enter it, or releases oil into the chamber so cross contamination is eliminated.
- Wool felt provides, even without oil, a near constant co-efficient of friction and this does not change even as the seal ages within the chamber. The normal reason for changing a seal would be to replace an older seal that no longer correctly sits in its position due to wear.
Various types/grades of felt are available, all in a wide thickness range. Grey felts and White felts operate to exactly the same levels of absorption and endurance given that they contain the same wool contents, the only difference between them being personal colour choice.
Softer felt seals tend to swell more in a liquid environment and so will conform to surface irregularities better than harder seals, however harder felt seals can be more accurately machined and in most cases offer enhanced life expectancy.
Alternative materials.
Not everyone believes a felt seal is the best for their systems and many new and exotic materials have been used in the recent past with varying success.
Polyethylene Foam and EVA Foam
We can offer a variety of either pure Polyethylene or Polyethylene/EVA blended materials to suit your application
This closed cell synthetic plastic foam material is available in a number of hardness levels and even in some cases some rather bright colours. It is impervious to liquids and as such cannot absorb lubricants.
We have a wide range of foams available to suit all chambers and applications in all ranges of machines thicknesses.
Our special CNC cutting platform can replicate the OEM seal perfectly.
It provides parallel cut surfaces which hug the profile of the chamber and ensure a perfect fit time after time.
Find out more here:
Your End Seals. Our Custom Service
In order to offer the best End Seal for your application all we need is either a sample or drawing of the seal required and we will offer our best engineered solution. If your seals are leaking or you feel like they are being changed too often due to failure maybe its time for a change.
We can provide samples for extended trials and can manufacture seals for all the major Doctor Blade Systems out in the field including among the more popular types, Schiavi, Bobst, Comexi, Tresu, F & K, Windmoller, Harris & Bruno, Gallus, Advanced and all after market chambers available.