Marcado directo de piezas: códigos de barras en metal, vidrio y plástico
Permanently marking barcodes on industrial parts — laser etching, dot-peen, chemical etching, and ink-jet methods for Data Matrix DPM.
Direct Part Marking: Barcodes on Metal, Glass & Plastic
Direct Part Marking (DPM) permanently marks barcodes on the surface of industrial parts, eliminating labels that can peel, fade, or be swapped. Data Matrix is the standard symbology for DPM due to its compact size and robust error correction.
Marking Methods
| Method | Process | Materials | Resolution |
|---|---|---|---|
| Laser etching | Laser ablates or discolors surface | Metal, plastic, glass, ceramic | Very high |
| Dot peen | Pneumatic pin creates dot impressions | Metal, hard plastic | Moderate |
| Chemical etching | Acid etches the surface | Stainless steel, titanium | Moderate |
| Inkjet | High-speed ink application | Any surface | High |
| Electrochemical | Electrical current + electrolyte | Conductive metals | Moderate |
Laser Etching (Most Common)
Laser marking creates barcodes by:
- Ablation: Removing surface material (creates a tactile mark)
- Annealing: Heating the subsurface to create a color change (smooth surface)
- Carbonization: Charring the surface for dark marks on light materials
Different laser types suit different materials:
| Laser Type | Best Materials |
|---|---|
| Fiber laser | Metals, some plastics |
| CO2 laser | Organic materials, glass, some plastics |
| UV laser | Plastics, glass, sensitive materials |
Dot Peen Marking
A carbide or diamond-tipped pin is driven pneumatically to create a series of dots that form the Data Matrix cells:
- Each dot represents a dark bar or space; the basic unit of barcode width." data-category="Barcode Anatomy & Structure">module
- Absence of a dot represents a light module
- Depth: typically 0.05-0.15mm
- Speed: 2-5 characters per second
Dot peen is lower cost than laser but produces lower contrast marks.
Data Matrix for DPM
Data Matrix is the standard for DPM because:
- Small size: 2.5mm minimum, fitting on small parts
- No quiet zone: Maximizes the marking area
- Error correction: ECC 200 handles surface imperfections
- Omnidirectional: Reads regardless of part orientation
ISO/IEC TR 29158 Quality Grading
DPM barcodes are graded under a different standard than printed barcodes:
- Multiple lighting angles are used (30, 45, 90 degrees)
- Cell contrast is evaluated under each lighting condition
- The best lighting angle determines the grade
- Minimum grade requirements vary by industry
Applications
| Industry | Parts Marked | Method |
|---|---|---|
| Automotive | Engine blocks, transmission parts | Dot peen, laser |
| Aerospace | Turbine blades, structural components | Laser etching |
| Electronics | PCBs, semiconductor packages | Laser |
| Medical | Surgical instruments, implants | Laser etching |
| Defense | Weapons components, ammunition | Dot peen, laser |
DPM Scanning
DPM barcodes require specialized scanners:
- DPM-capable imagers: Use advanced lighting (diffuse, dome illumination)
- Polarized lighting: Reduces glare from metallic surfaces
- Multi-angle illumination: Different angles reveal different marks
- Image processing: Algorithms optimized for low-contrast marks
Standard retail scanners cannot reliably read DPM barcodes.
Implementation Steps
- Select the marking method based on your material and environment
- Determine the minimum practical Data Matrix size for your parts
- Mark test parts and verify with a DPM verifier (ISO/IEC TR 29158)
- Test readability after any post-marking processes (heat treatment, coating, etc.)
- Establish marking parameters (power, speed, depth) for each part type
- Implement inline verification in production