# Laser engraving

Material-removal engraving versus other laser marks, material and optical dependencies, depth and resolution, and acceptance of text, graphics and direct-part codes.

Reviewed: 2026-11-01

Tags: processes, shaping, laser, marking

A **25.4 mm-wide raster with 600 equal cells** and no rescaling has **42.33 µm digital pitch**. At 300 cells it is **84.67 µm**. Measure the actual groove width, depth and separation on the marked material. Spot size, pulse overlap and material response determine whether neighboring cells remain distinct.

Specify material removal and required depth for a recessed engraving. TRUMPF distinguishes engraving from annealing, black marking, color change and foaming. [TRUMPF: marking procedures](https://www.trumpf.com/en_INT/solutions/applications/laser-marking/)

## Define the mark before selecting the process

| Required result | Question to resolve |
| --- | --- |
| Recessed text or geometry | What depth, width, edge shape and residual material are acceptable? |
| High-contrast surface mark | Is removal permitted, or must the original surface geometry remain? |
| Coating contrast | Is the coating removed, transformed or retained, and what substrate exposure is allowed? |
| Machine-readable code | Which symbol, data, module size, location and verification requirements apply? |
| Decorative image | Which artwork, final scale, tonal rendering and sample appearance define acceptance? |

TRUMPF's annealing description identifies an oxide-film color mechanism on suitable metals. Its smooth-surface result is different from a recessed engraving. Do not convert a request for an annealed identification mark into a deep engraved feature without confirming the drawing and service requirements. [TRUMPF: annealing mechanism](https://www.trumpf.com/en_US/solutions/applications/laser-marking/annealing/)

For quoting, provide the substrate grade and condition, coating stack and thickness where relevant, surface finish, released artwork/data and mark location. Identify prohibited surfaces, nearby seals or electronics, minimum remaining wall and any load-sensitive region. Neither a material name nor a laser power rating defines the complete application.

## Material response and laser selection

TRUMPF relates marking response to wavelength, pulse duration and irradiance as well as material. Its engraving guidance describes adjustable pulse conditions and localized material removal. These are process dependencies, not evidence that one machine setting produces the same depth or finish on another alloy, polymer or coating. [TRUMPF: material interaction](https://www.trumpf.com/en_INT/solutions/applications/laser-marking/), [TRUMPF: engraving](https://www.trumpf.com/en_INT/solutions/applications/laser-marking/laser-engraving/)

Specify the actual source, optics, focus arrangement, scan strategy and material state used in the trial. Review changes in coating, color/filler, surface preparation or part geometry before transferring a recipe. A vendor's example of a durable mark does not establish fatigue, corrosion or chemical compatibility of the particular finished component.

Material identification also controls whether processing is suitable at all. Trotec explicitly excludes PVC and other identified chemistries from its laser cutting/engraving guidance because hazardous gases or dust can harm people and equipment. It advises checking exact ingredients in flame-retardant materials. Do not approve unknown synthetic leather or plastic from appearance alone; obtain composition and the equipment/material supplier's supported process. [Trotec: unsuitable materials](https://www.troteclaser.com/en-gb/resources/faqs/unsuitable-materials-for-laser-processing)

## Artwork resolution is not feature accuracy

Trotec's resolution guidance describes heat-related enlargement and overlap of engraved dots and shows that preferred image resolution varies with material and graphic content. Higher nominal DPI is therefore not an automatic improvement in small-feature separation. Its examples also relate resolution and focus offset to processing time; they should not be imported as universal settings. [Trotec: engraving resolution](https://www.troteclaser.com/en-us/helpcenter/software/graphics-software/resolution-laser-engraving)

Record final artwork dimensions, units, font handling, rasterization and any grayscale-to-process mapping. Inspect the actual output at final scale. A fine source image can lose detail through dot growth, optics, motion or material response; a vector outline likewise needs a qualified resulting line width.

Focus and positioning belong in the process definition. Identify whether the marking surface is flat, stepped or curved, how it is located and whether focus changes over the mark. Evaluate position relative to part datums, not just placement in the artwork canvas. A nominal scan field or commanded coordinate does not establish the resulting feature tolerance.

### Original pixel-pitch calculation

Assume a **25.4 mm-wide** raster represented by **600 equal pixel cells**, with no rescaling:

`nominal cell pitch = 25.4 / 600 = 0.04233 mm = 42.33 µm`

Use physical measurements for spot size, groove width, depth and feature separation.

## Depth, passes and time

Define engraving depth relative to a stated reference surface and specify whether it means minimum depth, average recess, deepest point or another evaluated quantity. Agree how redeposited material, raised edges and surface texture are treated. A contrast image cannot replace a depth measurement.

Use representative trials to establish passes and any intervening cleaning or focus adjustment. Do not assume that twice the passes gives twice the depth: the qualified result must include the actual geometry and surface condition as the recess develops. Keep the delivered state after cleaning or secondary finishing explicit.

### Original idealized scan-time calculation

Assume an invented **20 mm × 10 mm** fully hatched rectangle, **0.050 mm** hatch spacing and a convention giving **200 lines**, each **20 mm** long. Assume constant marking speed **1,000 mm/s**:

- Marking distance per pass: 200 × 20 = **4,000 mm**.
- Ideal marking travel time: 4,000 / 1,000 = **4 seconds**.
- Five identical passes: **20 seconds** of ideal marking travel.

This excludes jumps, acceleration, turnarounds, delays, contour passes, loading, focus changes and cleaning. It is neither a production-cycle prediction nor a laser-setting recommendation. It does not specify pulse energy, frequency, spot overlap or achieved depth. Compare quotations against the same finished mark and cycle boundary.

## Code quality and service durability

For a direct-part code, separate correct encoded data, successful decoding under a selected setup, and formal symbol-quality verification. **ISO/IEC 29158:2025**, edition 2, **March 2025**, describes modifications to ISO/IEC 15415 methodology for direct-part marks, including illumination, measurement, grading and reporting. Its publisher record identifies the 2020 edition as withdrawn. Specify the applicable edition and application requirements rather than silently relying on an older “TR 29158” label. [ISO: current DPM quality specification](https://www.iso.org/standard/87123.html)

The public scope is not a universal required grade or an instruction to use one lighting setup for every surface. Agree verification parameters and reporting under the applicable application specification. A mark that decodes on one phone has not thereby demonstrated the ordered verifier result.

Test required durability after the relevant cleaning, abrasion, thermal exposure, coating or other service condition. Depth, optical contrast and resistance to service exposure are different acceptance questions. If local material damage or corrosion matters, include the required material/surface evidence instead of treating legibility alone as approval.

## Manufacturing handoff

Provide four groups of information:

1. **Part and material:** grade/condition, coating, surface preparation, geometry, location datums and prohibited regions.
2. **Mark definition:** controlled artwork or data format, final size, depth/line requirements, code module and quiet-zone requirements where applicable.
3. **Qualified route:** source/optics, fixture and focus, scan/pass strategy, cleaning and final finishing state.
4. **Acceptance:** content and position checks, depth/appearance criteria, code verification settings and grade where ordered, service tests, sampling and traceability.

The cited manufacturer web pages have no separately verified technical issue date here. Their capability descriptions do not establish a universal speed, DPI, power, material list or depth. Both calculations and the handoff structure are original.

## Related reference

[Manufacturing processes](../index.md)