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Laser Marking & Engraving

Marking faster is easy; marking faster and legibly is the actual problem

Scan speed, pulse frequency and hatch spacing interact. Push one without the others and the mark thins out or the characters distort.

By LasersNews Desk··2 min read
A skilled artisan works on intricate metal engraving under focused lighting in a workshop.
Photo by Juliano Couto on Pexels

Cycle time pressure on a marking cell usually produces the same instinct: increase scan speed. The result is often a mark that is faint, patchy or geometrically distorted, and the underlying reason is that scan speed is one of three coupled parameters.

The coupling

A marking laser fires pulses at a repetition rate while the beam moves. The spacing between successive pulses on the surface is scan speed divided by repetition rate. That spacing determines pulse overlap, and overlap determines whether the mark is continuous or a row of separate spots.

Increase speed without increasing repetition rate and overlap falls. The mark becomes a dotted line rather than a solid one.

Increase repetition rate to compensate and pulse energy falls, because average power is fixed. Lower energy per pulse may drop below the threshold for the marking mechanism, so the mark becomes faint.

Hatch spacing

For filled areas, the spacing between adjacent scan lines matters as much as pulse spacing. Widen it to save time and the fill becomes striped. Narrow it for quality and time rises proportionally.

Hatch angle also matters: alternating angle between passes produces more uniform fill than repeating the same direction, at no time cost.

Scanner dynamics

Beyond a certain speed the scanner itself becomes the limit. Galvanometer mirrors have inertia, so corners and direction changes require deceleration. Commanding a speed the scanner cannot achieve produces rounded corners and distorted characters — the geometry degrades even though the parameters look correct.

Delay parameters — jump delay, mark delay, polygon delay — exist to manage this, and they are the most commonly mistuned settings on a marking system. Too short and the beam fires before the mirrors settle; too long and cycle time inflates.

The practical approach

Optimising means adjusting speed, frequency and power together against a legibility criterion, then tuning delays for geometry, then verifying with a grading reader rather than by eye.

Shops that optimised by raising speed alone generally arrived at a cell that was faster and produced marks that failed customer grading — which is slower, once the rework is counted.

This article was produced by the LasersNews AI desk and reviewed by our editors.

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