🚗 Technical Cleanliness of Components (VDA 19.1)
Technical cleanliness testing of automotive components via extraction of particulate contaminants with gravimetric and microscopic analysis. Key standard in the automotive industry.
Overview
Technical Cleanliness (TC) is a critical quality parameter in the automotive industry. The VDA 19.1 standard, developed by the German Association of the Automotive Industry (Verband der Automobilindustrie), defines uniform methods for testing particulate contamination on functionally relevant vehicle parts. The first edition was published in 2004, the second — revised — in 2015.
Particulate contamination (metallic, non-metallic, fibers) can cause failures in hydraulic, injection, braking, steering, and air conditioning systems. A single metallic particle >200 µm in a common rail system can block an injector and lead to engine damage. Therefore, OEMs (BMW, VW, Daimler, Stellantis) require suppliers to provide documented technical cleanliness in accordance with VDA 19.1.
The test process consists of three stages: extraction of particles from the component surface (rinsing, ultrasound, shaking), filtration of the suspension on a membrane filter, and analysis of particles by gravimetric method (total mass) and/or microscopic method (size distribution, classification as metallic/non-metallic/fibers). Results are compared with limit values established by the customer (so-called CCC — Component Cleanliness Code).
VDA 19.1 is the reference standard in Europe; its international equivalent is ISO 16232. Both standards are technically convergent, although they differ in procedural details. A technical cleanliness laboratory requires a cleanroom of ISO class 7–8 or a dedicated laminar flow cabinet.
Method principle
The test principle is based on controlled extraction of contaminant particles from the surface of the tested component using an extraction liquid (most commonly isopropanol, test naphtha, or aqueous solution with surfactant). Extraction is performed using one or a combination of methods: pressure rinsing (spray rinsing), ultrasonic bath, or agitation. The resulting suspension is then filtered under vacuum through a membrane filter (typically 47 mm, 5 µm porosity). The filter is subjected to gravimetric analysis (weighing on an analytical balance with 0.1 mg accuracy) and microscopic analysis (optical microscope with automatic particle counting or SEM-EDX for chemical composition identification). Results are expressed as CCC — component cleanliness code, indicating the number and size of particles in defined size classes (from 5 µm to >1000 µm).
Applications
- Technical cleanliness control of injection system parts (common rail, injectors)
- Verification of brake system component cleanliness (ABS, ESP)
- Testing of steering system component cleanliness (EPS)
- Control of turbocharger and engine component cleanliness
- Validation of industrial washing processes
- Supplier audits in the automotive supply chain (Tier 1, Tier 2)
- Testing of packaging and assembly tool cleanliness
- Technical cleanliness control in electromobility (e-drive, batteries)
Key parameters
| Parameter | Value |
|---|---|
| Particle size classes | 5–15, 15–25, 25–50, 50–100, 100–150, 150–200, 200–400, 400–600, 600–1000, >1000 µm |
| Gravimetric detection limit | 0.1 mg (analytical balance) |
| Membrane filter porosity | 5 µm (standard), 0.8–8 µm available |
| Filter diameter | 47 mm (standard), 25 or 90 mm optionally |
| Extraction liquid volume | Dependent on part surface area, typically 0.5–5 L |
| Room cleanliness class | ISO 7–8 according to ISO 14644-1 or laminar cabinet |
Standard
- Standard number
- VDA 19.1:2015 (2. wydanie)
- Title (PL)
- Kontrola czystości technicznej — Zanieczyszczenie cząstkami stałymi części funkcyjnych w motoryzacji
- Title (EN)
- Inspection of Technical Cleanliness — Particulate Contamination of Functionally Relevant Automotive Parts
Step-by-step procedure
1. Workstation preparation
Check cleanliness of extraction chamber — perform blank test (extraction without component). Particle mass on blank must be <10% of CCC limit value.
2. Extraction liquid preparation
Prepare appropriate volume of clean extraction liquid (isopropanol, naphtha, or aqueous solution with surfactant) according to test instructions.
3. Particle extraction — rinsing
Place component in extraction chamber. Rinse all functional surfaces with liquid under controlled pressure (1–4 bar), collecting rinse into container.
4. Particle extraction — ultrasound (optional)
Immerse component in ultrasonic bath with extraction liquid. Parameters: frequency 25–40 kHz, time 5–15 min, temperature 20–40°C.
5. Decay test
Repeat extraction 3 times to confirm that procedure removes ≥90% of particles. Mass from subsequent extractions should decrease and third result should constitute <10% of total.
6. Suspension filtration
Filter all collected extraction liquid through 47 mm / 5 µm membrane filter under vacuum. Rinse funnel and container 3× with clean liquid.
7. Filter drying
Dry filter in dryer at temperature 60–80°C for minimum 30 min or to constant mass. Cool in desiccator min. 15 min.
8. Gravimetric analysis
Weigh filter on analytical balance (0.1 mg). Calculate particle mass: m = m_after_filtration − m_empty_filter. Subtract blank value.
9. Microscopic analysis
Place filter under microscope with automatic scanning. System counts particles in size classes, classifies them as metallic (shiny), non-metallic (matte), and fibers.
10. Result classification (CCC)
Convert results to component cleanliness code (CCC) according to VDA 19.1. Compare with limit values established by customer (OEM).
11. Documentation and report
Prepare test report containing: sample identification, extraction parameters, gravimetric and microscopic results, CCC code, photos of largest particles, compliance assessment.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Extraction chamber (spray cabinet) | CleanControlling CC-SC, Hydac CTU, JOMESA extraction cabinet | 80 000–250 000 PLN |
| Ultrasonic bath | Bandelin Sonorex DT 1028, Elma S300H | 5 000–25 000 PLN |
| Optical microscope with particle analysis | JOMESA CleanMaster, Zeiss Axio Imager, Olympus BX53M | 120 000–400 000 PLN |
| Analytical balance (0.1 mg) | Mettler Toledo MS205DU, Sartorius Quintix 224 | 8 000–25 000 PLN |
| Vacuum filtration set | Merck Millipore, Sartorius, Pall | 3 000–8 000 PLN |
| Laminar cabinet / cleanroom | Weiss Technik, Spetec, HEPA H14 | 15 000–80 000 PLN |
| SEM-EDX (optional) | Thermo Fisher Phenom XL, Zeiss EVO, JEOL JSM-IT500 | 400 000–1 500 000 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Isopropanol analytical grade | 67-63-0 | Extraction solvent, purity ≥99.5%, 2.5–10 L |
| Test naphtha (Exxsol D40/D60) | 64742-48-9 | Hydrocarbon extraction solvent for oiled parts, 5–20 L |
| Membrane filters 47 mm / 5 µm | — | Cellulose or nylon, white or with grid, for gravimetric and microscopic analysis, pack of 100 |
| Deionized water with surfactant | — | Water with conductivity <1 µS/cm with addition of 0.1–0.5% nonionic detergent (e.g., Deconex) |
| Acetone analytical grade | 67-64-1 | For cleaning laboratory equipment, purity ≥99.5% |
Health and safety (OHS)
- Isopropanol and test naphtha — flammable, work away from ignition sources, fume hood
- Safety glasses, nitrile gloves, and laboratory coat mandatory
- Ultrasound — do not immerse hands in bath during operation, hearing protection during prolonged exposure
- Cleanroom — follow entry procedures (protective clothing, airlock)
- Extraction liquid waste — collect and dispose of according to hazardous waste regulations