Technical Cleanliness: Quality Standards under VDA 19

Technical Cleanliness refers to the defined state of a component, assembly, or system regarding particulate contamination—specifically, solid particles that remain on or in a component after the manufacturing process. VDA 19 is the standard series from the German Association of the Automotive Industry that defines these requirements. It is divided into two parts: VDA 19.1 for component analysis and VDA 19.2 for cleanliness management during production.

For automotive suppliers producing mechanical parts, hydraulic systems, or electric motor components, technical cleanliness is a critical quality attribute—especially with the rise of electromobility.

Why Technical Cleanliness is Gaining Importance in E-Mobility

While cleanliness has been a standard in hydraulics for decades, the scope has shifted. Electromobility drives requirements into areas that previously had less stringent rules:

• Electric Motors & Power Electronics: Conductive particles (metal chips or carbon) can cause short circuits.
• Battery Systems: Metallic particles can lead to dendrite formation and internal cell shorts.
• Fuel Cells: Extremely tight tolerances regarding particle contamination in gas channels.

VDA 19.1: Component Cleanliness Analysis

VDA 19.1 defines how to measure the quantity and size of particles on a component. The standardized process follows these steps:

1. Extraction: Particles are removed from the component using pressure rinsing, ultrasonic baths, or agitation with a defined extraction liquid.
2. Filtration: The liquid is passed through an analysis filter.
3. Analysis: The filter is evaluated gravimetrically (total mass of residue) and optically (automated microscopy) to determine particle size distributions.

The result is a Cleanliness Certificate containing the total residue in milligrams and particle size classes (e.g., Class B to K) based on VDA 19 classification.

VDA 19.2: Cleanliness Management in Production

VDA 19.2 is the operational part of the standard. It describes how to systematically maintain and prove cleanliness throughout the manufacturing process:

• Process Design: Designing manufacturing steps to minimize particle entry (e.g., optimized deburring, tool maintenance).
• Cleanliness Environments: For sensitive parts, defined "Clean Zones" or cleanrooms (ISO 14644) may be required.
• Cleaning Validation: Proving that cleaning systems (washers) reliably reach the required cleanliness class.
• Environment Monitoring: Using "sedimentation plates" to measure how many particles from the ambient air land on work surfaces.

Cleanliness Classes and Particle Limits

Cleanliness requirements are usually specified as particle limits in a Cleanliness Code or an X-diagram. This code defines the maximum allowable number of particles of a certain size per component or per unit of surface area.

OEMs define these requirements product-specifically. For safety-critical E-mobility components, the requirements are significantly stricter than for traditional mechanical parts, often focusing on "metallic, shiny" particles that are electrically conductive.

Documentation: What Must Be Recorded

The duty to document technical cleanliness is extensive:

• Product Level: Cleanliness specifications, test plans, and cleaning validation records.
• Batch Level: Analysis results per test batch with timestamps, inspector names, and pass/fail results.
• Process Level: Parameters of cleaning systems (temperature, pressure, detergent concentration), filter change logs, and medium quality checks.
• Environment: Particle counting logs for ambient air in clean zones.

Integrating these results into an MES (Manufacturing Execution System) or QM system allows for batch-specific tracking, which is a major advantage during audits or when investigating complaints.

FAQ

What is the difference between technical cleanliness and general plant hygiene?

Plant hygiene concerns general order and safety (housekeeping). Technical cleanliness is a measurable product property. It defines quantitatively how many particles of what size are permissible on a specific component to ensure its function.

Which industries besides automotive have similar requirements?

Aerospace, medical technology, semiconductor manufacturing, and hydraulics/pneumatics use comparable standards. The VDA 19 methodology is often used as a global reference in these sectors.

How often must cleanliness analyses be performed in series production?

Frequency is determined in the Control Plan based on risk assessments and customer requirements. Common intervals are once per shift, per week, or per specific lot size.

What is the cost of a VDA 19.1 analysis?

In-house gravimetric analysis is relatively inexpensive if equipment is available. External accredited laboratory analyses with automated particle counting typically cost between €300 and €800 per sample, depending on the extraction effort and part size.