MIL-STD-130 and UID, 2D data matrix, choosing a laser marking method by material, and verifying marks so they scan for the life of the part.
A part number that wears off, a data matrix that will not scan, or a mark that cracks a coating can stop a delivery at receiving inspection. In aerospace and defense, the mark is part of the part. This guide covers what the main marking standards ask for, how to choose a marking method for the material, and how to make sure the mark is still readable years later.
Aerospace and defense programs depend on traceability. Every serialized part has to be identifiable through manufacturing, inspection, installation, maintenance and eventual removal. The mark is what connects a physical part to its records: material certifications, inspection reports and service history.
That is why marking requirements usually sit on the drawing or in the contract rather than being left to the supplier. They define what goes in the mark, where it goes, how it is applied and how it must be verified.
MIL-STD-130 is the U.S. Department of Defense standard practice for identification marking of military property. When a contract calls for Item Unique Identification (IUID), typically through DFARS clause 252.211-7003, the part needs a Unique Item Identifier (UII).
The UII is a globally unique number built from data such as the manufacturer’s identifier and the part’s serial number. For machine reading, it is encoded in a 2D Data Matrix symbol using ECC 200 error correction, usually alongside human-readable text.
Two points cause most of the confusion in practice:
There are two ways to put a UID on a part.
Nameplates and labels carry the mark on a separate plate attached to the part. They are common where the part surface is too small, too curved or too critical to mark directly, or where the plate can carry more information.
Direct part marking (DPM) puts the mark on the part itself. It cannot fall off or be separated from the part, which is why it is preferred for many components, but it has to be chosen carefully so it does not damage the surface or the material’s properties.
Laser marking covers several distinct processes. The right one depends on the material, the surface finish, and what the mark must survive.
| ANNEAL | Heats the surface to change its oxide color, without removing material. Typical on stainless steel and titanium, where corrosion resistance and a passivation-safe surface matter. |
|---|---|
| ABLATE | Removes a coating or anodize layer to expose the base material. Typical on anodized aluminum and coated parts, for high contrast. |
| ETCH | Removes a shallow layer of material. A general-purpose mark on bare metals. |
| DEEP ENGRAVE | Removes material in multiple passes to a measurable depth, for marks that must survive wear, rework, blasting or later coating. |
A common mistake is choosing the highest-contrast method without asking what happens next. A shallow mark can disappear under paint or a later surface treatment. An ablative mark on the wrong material can create a site for corrosion. The marking method should be decided with the part’s full process route in mind.
Before choosing a method, list what the mark has to survive in service and in manufacturing:
A mark that survives one of these can fail another. Deep engraving handles wear and coating well. Annealing preserves the surface on corrosion-sensitive alloys. Matching the method to the real exposure is what makes a mark permanent rather than merely visible.
A 2D code that looks fine to the eye can still fail to scan reliably. That is why direct part marks are verified, not just inspected visually.
ISO/IEC 29158 is the quality guideline for verifying direct part marked 2D symbols. Grading against it measures properties such as contrast, cell size and modulation, and gives an objective result that a receiving inspector can rely on. Asking for a verification report with marked parts removes guesswork from acceptance.
To quote a marking job accurately, a supplier usually needs:
If any of these are unclear, it is better to settle them before marking. A wrong mark on a finished part is expensive to correct.
Aerox Precision Services runs fiber laser marking in-house in Yorba Linda, California, on the same floor as its wire EDM, sinker EDM and hole-popping work.
For ITAR-controlled parts or data, contact us before sending anything so a compliant transfer is arranged first.
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