Page 39 - Training 2019

Keeping felt seals lubricated with petroleum jelly is key to their superior
performance and longer life. Felt end seals tend to dry out after the anilox
coating system is flushed with detergents, solvent or water. Applying
petroleum jelly to the radius portion of the seals after flushing the system
will ensure a tight fit and extend the life of the seals by reducing friction.

Choosing the right seal material and design for your application and
replacing end seals when necessary will help ensure that they do their job
of keeping ink and coating from leaking out of the chamber. Better yet, the
right seals will allow for proper doctor blade seating and a predictable and
even transfer of ink or coating from the anilox roller to the plate or blanket.
Despite their small cost, end seals have the power to save thousands in
waste and downtime.

TYPES OF END SEALS:

High-quality materials shown here are pre-soaked felt, high-density
neoprene, low-density neoprene and a combination seal with a neoprene
base with felt adhered to the radius.

Blue-foam and white-foam seals are the most common. These seals are
the least expensive but usually cause the most problems. You should
never be able to take a seal, put it in your hand and squeeze it to the
extent that your fingers almost meet. Can you imagine the instability
created on the chamber from such a flexible seal?

Also common is the seal made of a flexible poron base with a 1/4-inch
strip of felt adhered to the radius. Sometimes a small hole has been
drilled in the middle of the bottom to accommodate the chamber’s water
supply line or solvent supply line (depending on the type of ink used).
This line forces liquid into the hole and keeps the felt strip saturated for
lubrication. Because most of these supply lines leak and create a mess,
printers will, in some cases, cut off the supply line and simply apply
grease or Vaseline to the radius to keep it lubricated.

The rubber seal, made of a material similar to that of a tire, is also
common. This seal does not seat well because of the co- efficient of
friction created by the rubber and the anilox. In some cases, the radius of
the seal contains a bevel that acts as a flapper. This flapper is recessed
on the inside of the chamber. Ink is supposed to pressurize the bladder,
forcing the radius of the seal up to form its own sealing capabilities.
Instead, excessive leakage results.

CHAMBER BLADE END SEALS TRAINING MANUAL 5
Updated - 24 June 2019