Automated Code and Character Inspection for Automotive Components

What is automated code and character inspection?

During automated code inspection, a camera captures the marked area of a component. The machine vision software locates the code or characters, reads the encoded information and inspects it according to defined criteria.

Depending on the inspection task, the captured data can be compared with a target value, production order, database entry or an additional human-readable marking. The inspection result is then transmitted to the PLC, machine control system or a higher-level production system.

This allows components to be identified, assigned to specific variants, routed through subsequent process steps and rejected if they have been marked incorrectly.

The codes and characters that can be read reproducibly depend on factors such as the marking method, contrast, surface properties, code size, component position, contamination and optical accessibility.

Reading codes, checking content and evaluating code quality

These inspection tasks are often collectively referred to as code inspection, although they serve different purposes.

Reading codes

When a code is read, the system decodes the character string contained in it. This may be a serial number, material number, batch identifier or variant information.

Checking code content

The decoded content is compared with predefined target information. This makes it possible to check whether the code corresponds to the component, production order or current processing step.

Evaluating code quality

The optical quality of a marking can also be evaluated based on defined characteristics. These may include contrast, damage, incomplete code elements or defects within the code.

Standards-based quality classification or standardized code grading requires specifically designed inspection conditions. Whether this is required is therefore determined individually for each project.

OCR and OCV

OCR – Optical Character Recognition – reads unknown or changing letters and numbers.

OCV – Optical Character Verification – compares applied characters with a predefined character string or a trained reference image.

Both methods can be used to inspect serial numbers, type designations, date information and other human-readable content.

Which codes and markings can be inspected?

1D codes

Linear barcodes can be read and their contents compared with stored production data.

2D codes

Two-dimensional codes such as Data Matrix and QR codes store information in a compact area and are therefore particularly suitable for marking individual components.

Directly marked codes

With Direct Part Marking, or DPM, the marking is applied directly to the component surface. Typical methods include laser marking, dot peening and scribing.

Printed human-readable text

Printed letters, numbers and characters can be read using OCR or verified against predefined content using OCV.

Embossed and stamped characters

Recessed or raised markings can also be captured optically using suitable illumination. The decisive factor is whether the character contours can be made reproducibly visible.

Combined markings

Codes and human-readable text can be inspected within the same inspection step. This makes it possible, for example, to check whether the encoded content matches the visible character string.

Typical marking methods in automotive production

Laser marking

Laser-marked Data Matrix code with human-readable text on a metal component surface

Lasers create permanent codes and characters directly on metal, plastic or coated surfaces. Contrast and reflection characteristics can vary considerably depending on the material.

Dot peening

Dot-peened Data Matrix code on an automotive component

Dot-peened markings consist of individual indentations. For reliable optical inspection, the dot structure must be distinguished from the component surface using an appropriate illumination concept.

Inkjet printing

White inkjet marking on a brake component

Inkjet processes enable high-contrast markings on a wide range of component surfaces. Completeness, readability and content are among the characteristics that can be inspected.

Embossing and mechanical marking

Embossed characters on the metal surface of an automotive component

Depending on their depth, shape and surface structure, mechanically produced characters can be captured using 2D or 3D methods.

Challenges when reading directly marked codes

Automotive components place high demands on optical image acquisition. Codes and characters are often located on surfaces that do not provide consistent imaging conditions.

Typical challenges include:

low contrast between the marking and the component
reflective, dark or textured surfaces
curved or uneven component areas
varying positions and orientations
different marking depths and character shapes
contamination, oil or process residues
damaged or incomplete markings
small codes where installation space is limited
moving components and short cycle times

The camera, lens, illumination and evaluation method are therefore matched to the component, marking and production conditions.

How does automated code inspection work?

Multiple cameras capture the marking on a moving automotive component from different perspectives

1. Capture the marked area

The component is captured in a defined position or while it is moving. Depending on the position, geometry and number of markings, multiple cameras or views may be required.

Directional illumination makes a code on a metal component surface visible to the camera

2. Make the code or characters visible

The illumination is adapted to the surface and marking method. For embossed, laser-marked or dot-peened markings, a specific illumination direction can be crucial for making contours and height differences visible.

Machine vision software reads a Data Matrix code and checks its content, completeness and position

3. Read and inspect the content

The machine vision software locates the code or characters and determines the encoded content. Target values, spelling, completeness, position and other quality characteristics can then be checked.

Inspection result transmitted to the machine control system for rejection and documentation

4. Transfer the inspection result

The result is transmitted to the machine control system or a higher-level system. Depending on the system concept, incorrectly marked components can be rejected, blocked or routed for rework.

The decoded data, images and inspection results can also be documented if required.

Typical applications in automotive production

OCTUM develops inspection solutions for tasks including:

reading Data Matrix codes on metal components
inspecting laser-marked codes and serial numbers
reading dot-peened codes on engine and drivetrain components
OCR inspection of type, material and serial numbers
OCV inspection of predefined character strings
inspecting printed markings on brake components
reading embossed or stamped characters
checking the presence and completeness of a marking
comparing encoded data with human-readable text
assigning components to variants or production orders
controlling subsequent machining and assembly steps
providing data for traceability and documentation

Supporting traceability and process control

An unreadable or incorrect marking can prevent a component from being uniquely identified or processed correctly during subsequent production steps.

Inline code inspection allows the marking to be checked immediately after the marking process. Incorrect codes and characters can therefore be detected before the component passes through further machining or assembly processes.

Automated code and character inspection supports:

unique identification of components
assignment of variants and production orders
traceability throughout the production process
inspection immediately after the marking process
prevention of incorrectly marked components
automated control of subsequent process steps
documentation of read content and inspection results
objective and repeatable quality inspection

Integration into new and existing production systems

OCTUM adapts the inspection system to the respective production environment and available interfaces. Factors such as cycle time, available installation space, component movement, positioning, marking method and required data exchange are taken into account.

Depending on the application, different system concepts are possible:

stationary code-reading stations
inline inspection at production speed
camera-based systems with multiple views
compact smart camera solutions
PC-based OCR and OCV systems
inspection of stationary or moving components
integration into marking, machining and assembly stations
retrofitting of existing production systems
communication with PLCs and machine control systems
connection to databases and higher-level production systems
component- and variant-specific inspection programs

From feasibility study to commissioning

The development of an inspection solution begins by defining the codes, characters, target content and permissible deviations. Ideally, original components representing variations in contrast, position, marking depth and surface characteristics are available for testing.

As part of a feasibility study, OCTUM can determine the imaging conditions under which the markings can be captured and evaluated reproducibly. The results provide the basis for selecting the camera, lens, illumination and evaluation software.

OCTUM supports the project from concept development and implementation through integration and commissioning to support during ongoing operation.

FAQ about automated code and character inspection

Which codes can be read using machine vision?

Depending on the application, 1D barcodes, Data Matrix codes, QR codes and other 2D codes can be read. Codes marked directly on components can also be inspected if they can be made sufficiently visible using optical methods.

What does DPM mean in code inspection?

DPM stands for Direct Part Marking. A code or character string is applied directly to the surface of a component, for example using laser marking, dot peening or scribing.

What is the difference between OCR and OCV?

OCR reads unknown or changing character strings. OCV compares a marking with predefined or trained characters and checks whether the expected text is present.

What is the difference between code reading and code verification?

Code reading determines the encoded content. Content inspection additionally compares this value with a predefined value or data record. Standards-based code verification also evaluates the optical quality of a code under defined inspection conditions.

Can codes on reflective or low-contrast surfaces be read?

This is generally possible if the code can be made reproducibly visible using a suitable combination of illumination, optics and image evaluation. Feasibility depends on factors including the surface, marking method, code size and component geometry.

Can encoded data and human-readable text be compared?

Yes. A system can read both the encoded content and a visible character string and compare the two values. This makes it possible to determine whether the code and human-readable text match.

Is 100% inline inspection possible?

Every component passing through an appropriately designed inspection station can be inspected automatically. The codes, characters and quality characteristics that can be checked depend on their accessibility and the defined inspection limits.

Can a code inspection system be retrofitted?

Retrofitting is generally possible. Factors such as available installation space, component positioning, cycle time, illumination conditions and existing interfaces must be evaluated first.

Is your marking not listed?

Code types, marking methods and production conditions vary from one application to another. Together with you, we evaluate how your codes and characters can be captured optically and how the inspection can be integrated into your production process.

Talk to us about your components and markings.

OCTUM USA Inc.

14045 South Lakes Drive
Charlotte, NC 28273
USA

Phone: +1 (980) 431-9540
Email: info@octum-usa.com