Prototype Part Identification Guide: Laser Marking, Labels, Serial Numbers, Revision Control and Traceability

A prototype without clear identification can quickly become unreliable evidence. Two housings may look identical but use different materials. A test unit may contain a reworked bracket. A left-hand part may be mixed with a right-hand part. An engineering team may photograph a successful test but later discover that nobody recorded which drawing revision was installed.

Part identification prevents these problems by connecting each physical item to its digital definition, manufacturing history and test results. The mark may be a removable label, permanent laser code, engraved part number, printed data matrix, color tag or controlled package label. The right method depends on the prototype’s purpose, material, finish, size, environment and required life.

This guide explains how to select and specify prototype part marking, structure serial and revision identifiers, verify readability and durability, manage rework, and prepare a complete RFQ for traceable prototype and low-volume builds.

Why Prototype Identification Matters

Prototypes change faster than production parts. Geometry, firmware, material, finish, supplier and assembly method may all change between builds. When the physical hardware is not linked to a known configuration, test data loses value.

Effective identification supports five practical goals:

1. Configuration control: confirm which CAD model, drawing, BOM and software version the item represents.

2. Manufacturing traceability: connect the part to material, process, work order, batch, tool or machine records.

3. Test correlation: link inspection and performance results to the exact unit tested.

4. Logistics control: prevent mixed parts, incorrect assembly and shipping errors.

5. Learning and accountability: show which units were modified, rejected, approved or retained as references.

Identification is not merely an administrative label applied at the end. The available area, surface finish and marking process may affect product design, manufacturing sequence, cost and cosmetic acceptance. It should be discussed during prototype planning.

Start with the Traceability Question

Before choosing a marking technology, decide what the team must be able to answer later. For example:

• What is this part?

• Which revision is it?

• Which prototype build did it belong to?

• When and where was it made?

• Which material and finish were used?

• Is it an approved, test, reworked, rejected or reference unit?

• Which inspection report and test results belong to it?

• Is the marking itself part of the product design or only temporary process control?

The answers determine the data structure. A simple fit-check model may need only a part name and revision label. A verification build with destructive testing may need a unique serial number on every unit. A multi-supplier pilot assembly may need both part-level lot traceability and a final assembly serial number.

Avoid capturing information merely because it is possible. Every field must be generated, applied, recorded and maintained. Use the minimum structure that supports decisions and risk control.

Temporary, Semi-Permanent and Permanent Marking

Mark permanence should match the prototype lifecycle.

Temporary identification

Removable labels, low-tack tape, tags and bag labels are useful during early development. They are fast, inexpensive and easy to update when revisions change. They can be ideal when the visible surface must remain unmarked or the prototype will be photographed.

Temporary marks may fall off, transfer adhesive, become separated from the item or be removed during cleaning. If the mark is the only link to important data, use a backup method such as a traveler, matching package label or protected internal mark.

Semi-permanent identification

Durable printed labels, paint pens, ink marking and decals can survive normal handling but may still be removed or replaced intentionally. These methods suit engineering samples, test fixtures and low-volume equipment where the label needs to last through a defined project but is not intended as lifelong product identification.

Permanent identification

Laser marking, engraving, dot peen, molded or cast characters, chemical etching and some industrial printing methods can remain with the part for its service life. Permanent marking reduces separation risk and supports field traceability. However, it may alter the surface, weaken a thin section, create a cosmetic issue or become obsolete after a revision change.

A mark can be physically durable yet logically wrong. Permanence does not replace revision control. The marking data must be generated from an approved source and verified before release.

Choosing a Marking Method

No single process works for every prototype. Evaluate substrate, finish, geometry, contrast, data variability, quantity, cycle time and acceptance requirements.

The supplier should confirm feasibility with the actual material and finish. A process that works on bare aluminum may behave differently after anodizing. A laser that creates high contrast on one black polymer may produce almost no visible change on another.

Laser Marking for Prototype Parts

Laser marking is popular because it can create text, logos, serial numbers, one-dimensional barcodes and two-dimensional codes without a physical cutting tool. It also supports variable data efficiently. Yet “laser mark” is not a complete specification.

Depending on material and settings, the laser may:

• remove a coating to expose the substrate;

• darken or lighten a polymer;

• create oxide color on a metal surface;

• anneal a stainless surface;

• engrave a shallow recess;

• foam a plastic to create a light mark;

• carbonize material to create a dark mark.

These mechanisms produce different depth, contrast, heat input and corrosion behavior. Trials are important when the mark is cosmetic or functional.

Specify the required outcome rather than only the equipment. Define mark content, size, location, orientation, contrast, depth if relevant, surface condition and readability requirement. If the part has a coating, state whether the mark should remove the coating, change it or be applied before finishing.

Laser settings should be qualified on representative material. Resin fillers, pigment, alloy, heat treatment, coating chemistry and surface texture all affect the result. A supplier should not assume that settings from a visually similar part are suitable.

Mechanical Engraving and Machined Identification

For CNC-machined prototypes, a shallow engraved part number can be made during the machining process or in a secondary setup. This method is direct and permanent, and it may require little additional equipment.

Design considerations include:

• minimum character height and stroke width;

• tool diameter and internal corner radius;

• engraving depth;

• burr removal;

• available flat area;

• wall thickness under the mark;

• whether anodizing, plating or painting follows;

• whether the mark lies on a sealing, bearing or mating surface.

Engraving removes material. On thin or fatigue-sensitive components, even a shallow groove can be inappropriate. Keep marks away from highly stressed sections, precision datums, sealing lands, optical faces and contact surfaces unless engineering review approves the location.

When a mark is machined before coating, the coating may soften its edges or reduce contrast. When engraved after coating, exposed substrate may have different corrosion or cosmetic behavior. The process sequence must be stated.

Labels and Adhesive Selection

Labels appear simple, but adhesion is a material and environment problem. The label face stock, adhesive, print method and surface preparation must work together.

Important variables include:

• substrate surface energy;

• paint, powder coat, anodize or texture;

• dust, oil, mold release and cleaning residue;

• application temperature and pressure;

• time allowed for the adhesive to build strength;

• curved or flexible surfaces;

• exposure to heat, moisture, UV, fuels, oils or cleaners;

• expected removal without residue;

• abrasion and repeated handling.

A label that adheres well to smooth aluminum may lift from a textured polyurethane casting. A strong adhesive may damage paint or leave residue on a presentation model. For sensitive cosmetic surfaces, test representative labels before applying them to all parts.

Define whether labels are temporary, tamper-evident, repositionable or permanent. If a label carries a machine-readable code, verify it after application because curvature, wrinkles, glare and transparent laminates can reduce scanning performance.

Direct Printing, Pad Printing and Screen Printing

Printed marks are useful for product legends, logos, scales and fixed identifiers. Pad printing can reach moderately curved surfaces, while screen printing is effective for repeated graphics on suitable areas. Digital printing may support shorter runs and variable content.

Print quality depends on surface cleanliness, ink compatibility, pretreatment, cure and handling. The approval plan should cover:

• artwork revision and vector source;

• color and opacity;

• position and rotation;

• edge sharpness and fill;

• adhesion;

• cure state before packing;

• resistance to expected cleaners and abrasion;

• acceptable pinholes, smears or registration error.

If the mark is only for traceability, aesthetics may be secondary. If it is a customer-visible legend, treat it as a cosmetic feature with an approved sample and controlled inspection conditions.

Integral Marks in CAD, Additive Manufacturing and Soft Tooling

Embossed or recessed text can be included directly in the CAD model. Additive manufacturing can produce fixed identifiers with no separate post-process, and vacuum-cast or molded parts can reproduce characters from a master pattern.

Integral marks are useful for part numbers, left/right identification, orientation arrows and fixed warnings. They are less suitable for unique serial numbers unless every unit receives a separate file or tool insert.

Design the characters for the manufacturing process. Very small raised text may be fragile, trap support material or fail to fill. Deep recessed text can be difficult to clean and may create stress or sink. Surface texture and layer resolution affect readability.

For silicone tooling, the master establishes the mark. If the revision changes, the team may need to modify the master, patch the silicone tool, apply a secondary mark or build a new tool. Decide whether the revision should be integral before committing to the tool.

What Information Should Be Marked?

A prototype identifier often contains several layers of information:

• company or program code;

• part number;

• part name or abbreviated description;

• drawing or model revision;

• build phase or event;

• lot, batch or work-order number;

• unique serial number;

• mold, cavity, machine or supplier identifier;

• date code;

• material or process code;

• inspection or approval status.

Not all fields belong on the physical part. A compact serial number can point to a controlled database or build report containing the full record. This reduces mark size and avoids exposing unnecessary information.

For human-readable text, use an unambiguous structure. Avoid characters easily confused in the chosen font, such as O and 0 or I and 1, unless separators and context make them clear. Do not rely on color alone to communicate status because lighting, fading and color-vision differences can cause mistakes.

Part Number, Revision and Serial Number Are Different

These identifiers serve different purposes.

The part number identifies a design item or configuration family. Multiple physical pieces may share the same part number.

The revision identifies the released definition used to manufacture the item. It changes according to the customer’s configuration rules.

The serial number identifies one individual physical unit. It should normally remain unique even if the unit is reworked or upgraded.

A lot or batch number identifies a group made under common conditions. It can be sufficient when all units are interchangeable and individual test history is unnecessary. Serial-level control is preferable when units undergo different tests, contain different substitutions or will be returned from field use.

Do not create a new serial number merely to hide rework history. Keep the original identity and record the configuration change unless the governing procedure specifically requires replacement.

Designing a Serial Number System

A good serial system is unique, scalable and easy to validate. It does not need to encode every attribute.

Consider:

• a defined issuing authority;

• a reserved number range or database sequence;

• fixed length where machine systems benefit;

• allowed characters;

• check digits if manual transcription risk is high;

• separation between prototype and production ranges;

• rules for scrapped, lost or duplicate numbers;

• handling of supplier-generated serials;

• cybersecurity and confidentiality implications.

Overloaded “intelligent” serials can become brittle. If the number encodes year, factory, material, customer, project and revision, a process change may invalidate the structure. Often a simple unique ID linked to a record is more robust.

Never reuse a serial number from a scrapped unit for a new unit unless a controlled system explicitly supports that practice. Reuse can corrupt test history and create false traceability.

Revision Identification and Configuration Control

The physical revision mark must match the manufacturing data package. At release, confirm the revision of:

• 3D CAD model;

• 2D drawing;

• BOM;

• material and finish specification;

• artwork or label file;

• software or firmware where relevant;

• inspection plan;

• assembly and test instructions.

If these documents use different revision schemes, the build record should define the approved combination. Marking only the drawing revision can be misleading when firmware or BOM changed without a geometry change.

Prototype teams sometimes use labels such as Rev A+, Rev A-mod or Rev A2 informally. These may help local communication but should not replace the controlled revision. Record deviations and modifications separately so another team can reconstruct the exact hardware.

When a revision changes during an active build, segregate old and new parts physically. Update labels, work instructions and packing lists. Do not rely on memory or file timestamps to distinguish configurations.

Marking Location and Orientation

The best mark is readable when needed but does not harm function or appearance. Identify the location on the drawing with datums or a clearly bounded zone. A note such as “mark anywhere” invites inconsistency.

Avoid locations that are:

• sealing or gasket surfaces;

• precision fits or datum targets;

• bearing, sliding or electrical contact surfaces;

• highly stressed or fatigue-critical regions;

• thin walls where engraving may distort the part;

• optical surfaces;

• areas removed by later machining;

• surfaces hidden after assembly if service access is required;

• prominent cosmetic zones unless appearance is approved.

Define orientation relative to the installed part, drawing view or datum frame. For curved surfaces, state whether the text follows the curve and how scanning will occur.

If space is limited, consider marking an internal face, adding a small identification pad, using a two-dimensional code, or placing a permanent assembly serial on a larger component that links to individual part-lot records.

Character Size, Contrast and Readability

Readability depends on more than character height. Font, stroke width, spacing, surface texture, depth, contrast, lighting and viewing angle all matter.

Specify performance in context:

• readable by unaided eye at a defined distance;

• readable with specified magnification;

• scannable with the intended device;

• readable before and after coating;

• readable after the required environmental exposure;

• legible without disassembling the product, if needed.

Avoid universal minimum sizes without testing. A crisp high-contrast laser mark can be small, while the same nominal size on a rough 3D-printed surface may be illegible. Curvature may distort codes even when the printed dimensions meet the artwork.

For cosmetic marks, approve both content and appearance. Check alignment, uniformity, color, edge quality, surface damage and surrounding discoloration.

Barcodes, Data Matrix and QR Codes

Machine-readable codes reduce manual entry and can carry or reference more data than visible text. Choose the code type based on data capacity, available area, scanning distance, industry requirements and system compatibility.

A one-dimensional barcode typically needs more width. Data Matrix codes can carry useful data in a compact square and are common in industrial traceability. QR codes are widely recognized and can be scanned by many devices but may be larger for equivalent industrial marking needs.

The code should usually have a human-readable identifier nearby so the part remains identifiable if a scanner is unavailable or the code is damaged.

Verify:

• correct encoded data;

• symbol size and quiet zone;

• module shape and contrast;

• surface flatness or curvature;

• marking quality;

• scan performance with the actual device and software;

• duplicate detection;

• database lookup and record linkage.

A camera phone successfully reading one sample is not a complete verification method. For controlled applications, use an agreed grading or verification approach and test worst-case locations and finishes.

Marking Before or After Surface Finishing

Process sequence changes the result.

Mark before finishing

The finish may cover the mark, fill shallow engraving or reduce contrast. On the other hand, a coating can protect an engraved surface and keep exposed material from corroding.

Mark after finishing

The mark may remove anodize, paint or plating and expose the substrate. This can create strong contrast but may affect corrosion protection or cosmetic acceptance. Clamping and handling during the marking operation can also damage the finished surface.

Mark within the finish

Some laser processes selectively remove or modify a coating. Printed graphics may be applied between coating layers. These methods require coordination with the finishing supplier and clear process ownership.

State the sequence in the drawing or manufacturing plan. A vague callout can lead different suppliers to deliver visually and functionally different marks.

Material-Specific Considerations

Aluminum

Bare, anodized, painted and powder-coated aluminum respond differently. Laser marking anodize can create useful contrast, while engraving after anodizing exposes raw metal. Review corrosion, appearance and depth requirements. Keep mechanical marks away from thin walls and precision surfaces.

Stainless steel

Laser annealing can create dark marks with limited material removal when correctly controlled. Engraving and dot peen are also options. For corrosion-sensitive applications, validate that the method and any cleaning or passivation step preserve the required performance.

Engineering plastics

Laser contrast depends strongly on polymer type, additives and color. Heat may melt, foam, carbonize or distort the surface. Labels and printing require compatible adhesives or inks. Always trial representative resin, pigment and texture.

3D-printed parts

Layer lines and porous surfaces reduce print or label quality. Integral text may need larger features than on machined parts. Sanding, coating, dyeing or vapor smoothing can change the mark. Decide whether identification occurs before or after finishing.

Vacuum-cast polyurethane

Labels may struggle on textured or flexible surfaces, and laser response varies with resin and pigment. Integral characters can transfer from the master through the silicone mold, while painted or printed marks may be better for visible graphics. Cure the part fully before applying adhesive or ink according to the qualified process.

Elastomers and soft parts

Stretching, flexing and low surface energy make marking difficult. Consider molded characters, flexible labels, tags or package-level control. A rigid label may lift or restrict deformation.

Rework, Repair and Configuration Changes

Prototype parts are frequently modified. Holes are enlarged, shims added, fasteners changed, firmware updated or surfaces repaired. The identity must survive these changes without implying that the unit still matches its original definition.

A practical approach is to retain the serial number and update the configuration record with:

• modification description;

• authorizing deviation or work instruction;

• date and person performing the work;

• affected dimensions or interfaces;

• inspection after rework;

• current usability or test restrictions;

• photographs when helpful.

Use a visible status tag when teams must recognize modified hardware quickly. Do not overwrite the original revision mark in a way that destroys history. If the physical revision is updated, record who authorized it and how the previous state remains traceable.

When a mark itself is incorrect, control the correction. Grinding away an engraved serial, covering a label or re-marking over a laser code can create ambiguity. Define acceptable obliteration and replacement methods, and record the original and corrected identifiers.

Identification Through Assembly

An assembly may contain parts from several revisions and suppliers. The final assembly serial number should link to an as-built record, not merely to the planned BOM.

The as-built record can capture:

• assembly serial number;

• installed component part numbers and revisions;

• component serial or lot numbers where required;

• approved substitutions;

• reworked components;

• software or firmware version;

• assembly date and operator;

• inspection and test status;

• deviations and open issues.

Do not assume individual part marks will remain visible after assembly. Decide which identifiers must be accessible during service and which can be recorded before closure. Photograph hidden labels if that supports later verification.

For matched sets, use a set identifier in addition to individual part serials. This prevents approved left/right covers, calibrated pairs or color-matched panels from being separated during packing and use.

Status Identification Without Confusion

Teams often use colored stickers or handwritten marks for status: green for accepted, red for reject, yellow for hold. These visual aids are helpful but should supplement, not replace, controlled records.

Define who may apply or remove status labels. Prevent accepted and uninspected parts from sharing the same container. If status changes, remove or invalidate obsolete labels so a unit does not display contradictory signals.

Useful statuses include:

• awaiting inspection;

• accepted for fit check only;

• approved for functional test;

• not for customer shipment;

• rework required;

• hold pending engineering decision;

• reference sample—do not modify;

• destructive test complete;

• scrap.

Wording is often safer than color alone. A prototype that passes dimensional inspection may still be restricted from pressure or safety testing, so the status should state the scope of approval.

Inspection and Verification of Marks

Part marking should be inspected like any other product requirement. The control level depends on risk, but typical checks include:

• correct part number and revision;

• serial uniqueness;

• correct code data;

• location and orientation;

• readability or scan performance;

• character size and mark depth when specified;

• contrast and cosmetic quality;

• adhesion and cure for labels or inks;

• absence of burrs, distortion, burning or surrounding damage;

• correspondence with traveler, certificate and packing list.

Use first-article approval for a new material, finish, geometry or marking setup. A sample approval should include the actual mark content or a controlled representative pattern.

For variable serial data, verify both the marking system and the database transaction. A perfect mark that points to the wrong record is a traceability failure.

Durability Testing

Durability requirements should reflect the prototype’s use. A label on a one-day design review model does not need the same test plan as an identification mark on a pilot unit used outdoors for six months.

Possible exposures include:

• repeated handling and abrasion;

• cleaning agents and disinfectants;

• oil, coolant, fuel or sweat;

• humidity and water;

• temperature cycling;

• UV light;

• bending or vibration;

• packing and shipping friction.

Define the exposure method, duration and post-test acceptance. “Permanent” is not measurable by itself. The requirement may be that text remains readable, the code still scans, the label does not lift beyond an agreed limit, or the substrate shows no unacceptable damage.

Environmental tests can affect the whole part, so coordinate marking validation with functional prototype testing where possible.

Handling Small, Delicate or Cosmetic Parts

Some parts do not have a safe marking area. Tiny springs, optical windows, soft seals and high-gloss presentation panels may be damaged by direct identification.

Alternatives include:

• individual compartmented packaging with unique labels;

• removable protective film carrying the ID;

• an attached tag outside the functional area;

• a marked carrier or fixture that remains with the part;

• a tray map linked to serial positions;

• a mark on a hidden non-cosmetic edge;

• group-level lot control when individual identity is unnecessary.

Package-level control requires discipline. If items are removed, the system must preserve their identity. Do not place several visually identical revisions loose in the same bag.

Supplier and Customer Responsibilities

Clarify who creates identifiers, supplies artwork, applies marks, verifies data and maintains the traceability record.

The customer commonly owns the part number, controlled revision, artwork approval and serial-number policy. The supplier commonly owns process selection, equipment settings, mark application and in-process verification. Either party may issue serials, but there should be only one authoritative system.

For outsourced finishing or marking, the primary supplier should maintain control of data transfer, part segregation and return verification. The customer should not need to reconstruct which subcontractor handled a unit from incomplete shipping notes.

Change control applies to marking too. A change in label stock, adhesive, ink, laser method, location or code format may require notification when it affects function, appearance or validation.

Common Part-Identification Failures

Duplicate serial numbers

Duplicates arise from manual number generation, separate supplier ranges, spreadsheet copying or reusing scrapped IDs. Use a controlled issuing source and automated duplicate checks where practical.

Wrong revision on the part

The marking file may be older than the manufacturing file, or labels may have been printed before a design change. Release marking data as part of the same controlled package and verify it at first article.

Correct label on the wrong part

This is an application and segregation failure. Use single-piece flow, scan-to-verify systems or clear fixtures when similar parts are present.

Unreadable laser mark

Low contrast, wrong focus, surface curvature, unsuitable material or aggressive finishing can reduce readability. Trial the actual material and inspect after all downstream processes.

Label lifting

Review surface contamination, texture, curvature, adhesive selection, application pressure and dwell time. Do not simply choose a stronger adhesive if the finish could be damaged.

Mark placed on a functional surface

The drawing may not define a location, or the operator may choose the easiest accessible area. Create a marked zone and identify prohibited surfaces.

Traceability stops at shipping

Package labels may not match inspection reports, or the customer may remove parts without recording serials. Align physical marks, packing lists and digital records before delivery.

Rework breaks the history

A modified unit may receive an informal nickname rather than a controlled update. Retain the serial and record every approved change in the as-built history.

A Practical Implementation Workflow

1. Define the objective. Decide whether the mark supports configuration, testing, logistics, service, branding or regulatory needs.

2. Choose the traceability level. Select package, lot, part or individual serial control.

3. Structure the data. Establish part, revision, serial, lot and status fields.

4. Select the process. Match permanence, substrate, finish, quantity and environment.

5. Design the marking zone. Define location, size, orientation and prohibited areas.

6. Release controlled artwork. Link the marking file to the correct part revision.

7. Run representative trials. Use the intended material, finish and process sequence.

8. Approve first articles. Verify content, readability, appearance and substrate condition.

9. Control variable data. Issue serials, prevent duplicates and confirm database linkage.

10. Inspect and record. Check marks after all downstream operations.

11. Protect during packing. Keep individual or matched-set identity through shipment.

12. Maintain the history. Record rework, tests, status changes and final disposition.

Prototype Part Marking RFQ Checklist

Send the following information for an accurate quotation:

• 3D CAD and drawing revision;

• part number and name;

• quantity and future repeat estimate;

• material, heat treatment and surface finish;

• purpose of the mark;

• temporary, removable or permanent requirement;

• required marking method, or permission for supplier recommendation;

• exact text, logo, barcode or two-dimensional code artwork;

• variable data fields and serial-number source;

• marked location and orientation;

• character, code or logo dimensions;

• depth, contrast, color and cosmetic requirements;

• human readability and scanner requirement;

• process sequence relative to finishing;

• prohibited functional or cosmetic areas;

• environmental and durability exposures;

• first-article and approval requirements;

• inspection report or code-verification requirement;

• packaging, matched-set and label requirements;

• confidentiality or information-security restrictions;

• requested delivery date and destination.

Attach artwork in a suitable controlled format. Screenshots are useful for visual explanation but should not be the only source for production graphics or encoded data.

RFQ Template

Project: [program or build name]   Part / revision: [part number and released revision]   Quantity: [prototype and repeat quantity]   Material / finish: [complete specification]   Mark purpose: [configuration / test / logistics / branding / service]   Traceability level: [package / lot / unit serial]   Preferred method: [laser / engraving / label / print / supplier recommendation]   Mark content: [fixed text and variable fields]   Serial source: [customer list / supplier issue / database rule]   Artwork file: [filename and revision]   Location / orientation: [drawing zone or annotated image]   Size / depth / contrast: [requirements or approved sample]   Code verification: [scanner, data format and acceptance]   Durability: [handling, chemical, heat, UV or abrasion exposure]   Cosmetic limits: [visible zone and approved appearance]   Process sequence: [before or after finish]   Approval: [trial coupon, first article and approver]   Records: [inspection, serial list, photos or certificates]   Packing: [individual, matched set, bag/tray label]   Delivery: [date and destination]

Questions to Ask a Prototype Supplier

1. Which marking methods are compatible with the specified material and finish?

2. Can you run a representative trial before marking the complete batch?

3. How will you control artwork and revision data?

4. Who issues serial numbers, and how are duplicates prevented?

5. Can you verify barcodes or two-dimensional codes with the intended scanner?

6. Will marking occur before or after finishing, and what are the tradeoffs?

7. How do you protect cosmetic and functional surfaces during marking?

8. What records link the finished part to its material, process and inspection?

9. How will reworked or incorrectly marked parts be controlled?

10. Can you provide an as-built serial list with the shipment?

11. How are subcontracted marking operations controlled?

12. Which marking-process changes require reapproval?

Frequently Asked Questions

Should every prototype have a serial number?

No. Lot or package identification may be enough for simple design-review models. Use individual serial numbers when units have different configurations, tests, rework history or field use.

Is laser marking always permanent?

Laser marks are often durable, but permanence depends on the marking mechanism, material, finish and exposure. Define and test the required durability rather than relying on the word “permanent.”

Should the revision be marked on the part?

Mark it when physical configuration recognition is important and the change process can maintain accuracy. For fast-changing prototypes, a unique serial linked to an as-built record may be more flexible than a permanent revision mark.

Is engraving safe on thin parts?

Not automatically. Engraving removes material and may distort a thin wall or create a stress concentration. Review depth and location with the part’s structural requirements.

Can a label be applied to a textured or painted surface?

Often yes, but adhesion and removal effects must be tested on the actual surface. Texture, contamination, curvature and coating chemistry strongly influence performance.

Which code is best: barcode, Data Matrix or QR code?

Choose based on available space, data capacity, scanning system and customer requirements. Data Matrix is compact for industrial use; QR is broadly accessible; one-dimensional barcodes may fit simple established systems.

What should happen when a prototype is reworked?

Retain its unique identity and update the as-built record with the authorized change, inspection and status. Do not erase the original history.

Can the serial number be included in the 3D-printing file?

Yes, but generating a separate file for every unit adds file-control risk. For many parts, secondary laser marking, printing or labels may be easier to manage.

When should marking be performed relative to anodizing or painting?

It depends on the desired appearance, protection and contrast. Marking before finish may be covered; marking after finish may expose substrate. Define the sequence and approve a representative sample.

How do we identify parts that cannot be marked?

Use controlled individual packaging, tags, carriers, tray maps or assembly-level records. Ensure identity remains intact when parts are removed from the package.

What is the difference between a lot number and serial number?

A lot number identifies a group made under common conditions. A serial number uniquely identifies one unit. Select the level needed to connect hardware to its manufacturing and test history.

Should a human-readable ID accompany a machine-readable code?

Usually yes. Visible text provides a fallback when a scanner is unavailable or the code is damaged and helps operators detect obvious mismatches.

Conclusion

Prototype part identification turns physical hardware into trustworthy engineering evidence. A useful system connects each part or assembly to the correct design revision, material, process, inspection, test and rework history. The marking technology matters, but the data structure and control process matter just as much.

Choose permanence and traceability according to project risk. Define the marking zone, artwork, process sequence, readability and durability requirements. Approve representative trials on the actual material and finish, verify variable data, and preserve identity through assembly, testing and shipment.

AluPrototype supports prototype and low-volume parts with machining, additive manufacturing, vacuum casting, finishing, assembly and controlled marking options. Send your CAD files, material and finish specifications, quantity, marking artwork, serial-number requirements and delivery schedule for a practical manufacturability review and quotation.