Direct laser engraving of flexographic printing forms
Direct laser engraving is gaining a stronger position as an accepted alternative to photopolymerisation in the production of flexographic printing forms.
What is direct laser engraving? This is the process whereby the surface of the sleeve is modelled by means of ablation using a high-energy laser beam to create a raised image.
This process requires a high-powered laser because – in contrast to the very thin layer on a digital photopolymer form which is only a few microns thick – it is necessary to remove material to a depth of several tenths of a millimeter.
Controlled dot shapes
Technological advances now make it possible to exploit the fundamental advantages of direct laser engraving even more efficiently.
The high-energy laser beam is capable not only of leaving the material in place or removing it entirely, it can also release its energy in controlled doses according to the image data and thus produce screen dots with flanks of a defined form and gradient.
This is a significant benefit for flexographic printing as, besides the precision and design of the dot surface, the mechanical stability of the dots has a decisive impact on the quality of the printed product. This three-dimensional property of dot formation in laser engraving reinforces even the finest dots, affording more image contrast and printing form longevity.
In addition, laser energy can be precision-controlled to marginally engrave the elastomer surface lightly where fine tonal gradations are required. Thus a small dot may stand less high than, say, a solid area adjacent to it. In this way, solids with high ink transfer can be combined with fine screen work in one printing form.
This ‘electronic undercutting’ can be used to significantly enhance the quality of the printed image.
The use of direct laser engraved sleeves on modern flexographic presses requires no additional investments or machine modifications. The same inks and screen rollers are used as when working with photopolymer plates and sleeves.
Thanks to advances in laser technology and the transition from analogue to digital workflows, direct laser engraving has established itself as a technology bringing real advantages to flexographic printing in terms of economy and quality enhancement.
Balanced products – all from a single source
Böttcher offers a broad range of elastomers compounds which have been specially developed for laser engraving. These can be supplied in combination with hard or soft functional under layers.
We offer cylindrical and conical sleeves to suit all typical carrier systems. The base sleeves made of glass-fibre reinforced plastic (electrically conductive or non-conductive, according to your choice) are likewise manufactured by Böttcher.
The development of customised solutions is a strength of Böttcher. Our comprehensive product range and vertical manufacturing enable us to offer a complete technical consultation.
Other flexographic products:
- Flexo printing blankets
- Pan rollers
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