Böttcher offers flood coat sleeves “ready to print“. For the production a large stock of air mandrels according to the common mandrel systems (e.g. Stork, BCD,..) is available. If requested, we can cut-back the sleeve surface related to the web with and we can implement notches for the register pin.
Flexo sleeves can be modified by altering the con-struction of the fiberglass base sleeve, the elastomeric covering, as well as the entire build-up and wall thickness in a very flexible way related to the individual environment in the printing stop. Nearly all sleeve constructions can be combined with the various flexo compounds for the covering. In most print shops elastomer covered flexo sleeves are used as flood coating sleeves. Key reasons why, the need for (ITR) in the round elastomer sleeve for seamless printing, the high ink transfer rate and the high chemical resistance.
An additional advantage of sleeves with elastomeric covering is the opportunity to create each print repeat length. Especially in case of modern gearless presses with servo drive this is a benefit, because these presses are also not fixed to the gear-wheel based repeat steps.
Technology of Direct Laser Engraving
For the Direct Laser Engraving of sleeves and plates with elastomeric covering CO2 Laser, Diode Laser as well as high power fibre laser are used. Within this technology for the imaging of flexo printing forms, the laser beam removes the material directly down to the relief depth. In comparison to the two-dimensional removal of the thin back layer of the Laser Ablation Mask System of photopolymer by low energy lasers, the Direct Laser Engraving method provides the opportunity for a three-dimensional modulation of the dot relief.
3 x 3D effect – The advantage of Direct Laser Engraving, if dot accuracy matters
The three-dimensional modeling of the screen dot shape of directly engraved elastomer compounds offers the flexo printer the ability to increase print quality as well as to increase the service life of the printing form.
- A further advantage of Direct Laser Engraving technology is the opportunity to program an electronic adjustment, referred to as an “Undercut”. With this option, the top of the highlight dots is slightly reduced by the laser. Even at higher print pressure, the small dots resting beside the solid areas will not be over-squeezed.
- Due to the engraving of a defined shoulder profile, an optimal stabilization of the smallest dots in high light can be achieved.
- The shape area below the surface of the screen dot can be realized as a cylinder. This avoids a “geometrical dot gain” even during long printing runs in comparison to the simple cone shape of photopolymer printing forms.
Only the DLE technology uses the digital data of the repro file directly to design the three-dimensional shapes of the screen dots. This is simply and purely „true digital“.
BöttcherFlex DLE Sleeves
EPDM or SBR-based rubber compounds are mainly used for sleeves and plate coverings for the laser engraving process. This type of base polymer leads to specific chemical and physical properties. But also the type and quantity of the other ingredients influence the properties of the covering in a significant manner, e.g, regarding engraving speed or ink transfer. We offer an actual list of Böttcher Flexo compounds and will be pleased to advise you.
BöttcherFlex DLE Plates
For the top layer of the Böttcher plates for Direct Laser Engraving, special rubber compounds from our approved Flexo sleeve portfolio are used. At present, they are available with the common thickness of 1.14 and 1.70 mm. BöttcherFlex plates are supplied with a polycarrier on the back side as pre-cut parts or as a roll. The mounting of the plates can be done in a similar way to photopolymer plates.