Reading laser markings – Efficient traceability with reading devices

Direct part marking (DPM) using lasers is now standard practice in industrial marking. It enables the unique identification of parts, products, and components. However, it is only through the reliable reading of these markings with suitable industrial scanners that traceability is fully digitized – from series production to maintenance in the field. Whether serial numbers, DataMatrix codes, or plain text – the choice of the right reading system depends heavily on the application scenario. In this article, we compare inline, single-station, and mobile solutions and provide tips on reading laser-marked codes.

Reliable code reading is the final and most critical step in ensuring full industrial traceability:

• Traceability: Provides complete documentation throughout the entire product life cycle.
• Quality Assurance: Enables automatic checking for legibility, contrast, and code integrity in real-time.
• Efficiency: Guarantees fast, error-free data capture without manual input, saving time and money.
• Robustness: Modern DPM scanners are designed to reliably recognize damaged, low-contrast, or laser-engraved codes, even on curved or difficult surfaces.

Also read: The Importance of Traceability in Manufacturing

The industry typically relies on two main categories of reading systems, each suited for different environments:

Camera systems for automated production lines (Inline Vision Systems)

These systems, often integrated as stationary cameras or inline vision systems, are built for high-speed, high-volume production. They often feature AI-supported scanners and motion compensation to handle dynamic production environments.

Advantages of Inline Vision Systems:

• Real-time evaluation and data connection.
• High speed and throughput.
• Fully automated quality control (pass/fail).
• Seamless integration into ERP/MES systems.

Reading Systems for Flexible Testing (Mobile & Stationary)

This category includes traditional stationary systems for automated, fixed-point detection, as well as handheld DPM scanners for maximum flexibility.

Advantages of Mobile DPM Scanners:

• Flexible use (maintenance, decentralized control, quality checks).
• Low initial investment costs compared to full inline systems.
• Ideal for varying components or lower production volumes.
• Quick to set up and robust for industrial environments (dust, oil).

DPM and industrial scanners are designed to read several types of data formats, enabling comprehensive documentation and traceability:

• 2D Codes (DataMatrix, QR, Barcodes): These codes capture compact, machine-readable information such as serial numbers, batch numbers, and detailed production data (e.g., date, shift, location).
• Alphanumeric Text (OCR): Optical Character Recognition (OCR) allows scanners to read plain text (clear text) that is also used for visual inspection or manual readability checks by personnel.
• Standardized Identifiers (UDI/UID): Scanners are often validated to read mandatory industry-specific codes like UDI (Unique Device Identification), which is particularly relevant for surgical instruments and implant traceability in medical technology.

To successfully read the challenging Direct Part Markings (DPM), specialized technology is required:

• DPM Functionality: Dedicated algorithms built to handle codes marked directly into material.
• HDR+ Technology: Used for contrast compensation, making codes readable on difficult, shiny, or low-contrast surfaces.
• Liquid Lens Optics: Allows for variable working distances and quick refocusing.
• Verification: Systems supporting ISO/IEC TR 29158-compliant verification to ensure code quality meets international standards.
• AI-Supported OCR Recognition: Used for complex alphanumeric characters and visual inspection tasks.

Readability begins long before the scanner is powered on. Follow these steps for guaranteed traceability:

Ensure marking quality

• Achieve high contrast through targeted settings (e.g., annealing, matting).
• Maintain consistent marking depth and quality.
• Ensure the marking is easily accessible and as flat as possible.
• Verify compliance with standards such as UDI or GS1 from the design stage.

Select suitable scanner technology

• Consider the material, surface type, and environment (dust, oil, vibration).
• Choose based on code content (OCR vs. DataMatrix).
• Utilize Dome or directional LED lighting to minimize reflection.
• Choose optics like Liquid lens technology for variable distances.

Integration into the production process

• Ensure inline capability with triggering and robust data connection.
• Implement software interfaces to ERP/MES systems for automated data transfer.
• Use a Verifier for quality testing according to ISO/IEC TR 29158.

Training & maintenance

• Provide employee training on correct placement and scanning procedures.
• Ensure regular cleaning and calibration of reading devices.

Here’s the content organized into a clear table format:

• Conduct field tests with different laser settings and scanners
• Choose code placement strategically (protected but accessible)
• Post-processing (e.g., removal of smoke marks) to improve readability
• Simulate long-term readability through aging tests
• Link traceability systems with real-time data
• Consider GS1-compliant serialization as early as the design and procurement stages

GS1 is a uniform standard that enables globally consistent identification and traceability—ensuring this throughout the entire life cycle of components and products.

• Definition of applied standards
• ISO/IEC TR 29158: Quality assessment of DPM codes
• EN 15380: Labeling of railroad components