Anilox Roller Laser Engraving Surface Integrity
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Solution Overview
Problem
Laser engraving of anilox rollers with ceramic surfaces results in ceramic particles detaching and creating grooves, leading to stripes in printed images due to the manufacturing process, which extends the production time and service life is not sufficiently improved by existing methods.
Innovation Solution
Using a repetitively operated short-pulse laser to carve out indentations with multiple pulses in the cross-sectional profile, followed by a finishing operation like honing or polishing to create a smooth and durable surface, reducing the production time and enhancing the service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermal YAG lasers or CO2 lasers are used for laser engraving of anilox rollers with ceramic surfaces, then the roller surface can be engraved, but ceramic particles detach and form grooves leading to stripes in printed images
Solution Approach 1:
The patent uses ultrashort laser pulses with a pulse duration of less than 100 picoseconds to engrave the ceramic surface. The periodic pulsed action allows material removal through ablation without significant heat diffusion, preventing melting and subsequent particle detachment that occurs with continuous or long-pulse lasers. This resolves the contradiction by enabling engraving while maintaining surface integrity and preventing groove formation.
Solution Approach 2:
The patent fundamentally changes the laser pulse duration parameter from nanoseconds/milliseconds (thermal lasers) to picoseconds (ultrashort pulses). This parameter change shifts the material removal mechanism from thermal melting to direct ablation, eliminating the harmful effects of melted ceramic particles while maintaining effective engraving capability.
2Reliability
If the roller surface is heated again with a laser to close cracks and pores after engraving, then the service life is extended, but the production time increases to 10-12 hours
Solution Approach 1:
The patent extracts the harmful thermal effects from the laser engraving process by using ultrashort pulses that remove material through ablation rather than melting. This eliminates the need for subsequent heating steps to close cracks and pores, as the ultrashort pulse process inherently prevents their formation. The contradiction is resolved by removing the problematic thermal phase entirely from the process sequence.
Solution Approach 2:
The ultrashort laser pulse process achieves both material removal and surface quality improvement in a single continuous operation, eliminating the need for separate post-processing heating steps. The useful action of laser engraving inherently produces a clean, crack-free surface that requires no additional thermal treatment, thus reducing total production time while maintaining reliability.
3Manufacturing precision
If multiple grinding passes with diamond abrasive are used to achieve desired surface roughness, then the surface quality is improved, but the process becomes expensive and time-consuming
Solution Approach 1:
The patent replaces the mechanical grinding system with a laser-based ablation system using ultrashort pulses. Instead of using diamond abrasive to mechanically remove material and achieve surface roughness, the laser directly ablates the ceramic material with picosecond pulses, achieving the desired surface quality without mechanical contact. This substitution eliminates the time-consuming multiple grinding passes while maintaining or improving surface precision.
Solution Approach 2:
The patent changes the surface finishing mechanism from mechanical abrasion to optical ablation by using ultrashort laser pulses. This parameter change in the material removal mechanism achieves the desired surface roughness in a single step rather than requiring multiple grinding passes, thereby reducing both time and cost while maintaining manufacturing precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process significantly reduces production time and achieves a longer service life for anilox rollers without lengthening the manufacturing process, ensuring a smooth and durable surface for the doctor blade to slide on, thereby improving ink release and acceptance behavior.
Implementation Method 1
a repetitively operated short-pulse laser is used in order to carve out the indentations, with several laser pulses being used in each case in order to carve out the indentation in the cross-sectional profile
Implementation Method 2
the material to be removed is essentially ablated or vaporized
Implementation Method 3
followed by a finishing operation like honing or polishing to create a smooth and durable surface
Implementation Method 4
followed by a finishing operation like honing or polishing to create a smooth and durable surface
Data Source
AI summary
The invention relates to anilox rolls for anilox color decks, engraved by a short-pulse laser, wherein the cross-sectional shape of the engraved cells or hachures is machined out by a plurality of pulses of the repeatedly operating laser. The pulse energy and mean power of the laser are selected or set so that at least 0.5 cm3 of material/hour is ablated. The surface of the roll is subsequently smoothed or cleaned by a mechanical finishing step.