Residual Dirt Analysis – A Service by SLE Technology GmbH

Unless you do not have your own in-house cleanroom, we would be pleased to support you by conducting residual dirt analyses within the framework of your production process. In our test laboratory, your parts and components will undergo professional analyses in compliance with VDA 19 and ISO 16232. The SLE specialist staff at the residual dirt laboratory has been qualified and certified by the Fraunhofer Institute for production technology and automation IPA as well as by the quality management center of the German association of the automotive industry VDA QMC.

With state-of-the-art procedures, we examine parts and components, ranging from filigree sizes in millimeter ranges to large components, to be individually specified. The technical cleanliness of the specimen will be documented by means of decay curves. The results of your part/component testing will be documented in a detailed report, containing text and graphical illustrations on particle measurements as well as a gravimetric analysis, if required.

Our service portfolio furthermore comprises consulting services regarding cleanliness concepts in production and logistics processes as well as the development and design of individual, customized cleanrooms for our customers.

Your Benefit – Residual Dirt Analysis Services
by SLE Technology GmbH

  • outsourcing of part/component sampling, particle measurement, and industrial cleaning to experienced service provider
  • high-quality residual dirt analyses customized to your individual requirements
  • accurate particle analyses with state-of-the-art technology in an accredited test laboratory environment
  • VDA 19 and ISO 16232 certified
  • specialist staff qualified and certified by Fraunhofer IPA and VDA QMC (accredited technical cleanliness examiners)
  • quick and professional results without the typically high expenses of in-house analytical chamber
  • detailed test reports

Decay Curves – Your Residual Dirt Analysis Documentation

With the decay measurement, a part/component will be sampled several times to determine if the respective amounts of dissolved particles are decreasing. Thus it may be checked if a suitable extraction method or extraction process has been selected. The purpose of this procedure is to work out appropriate conditions, for instance test liquid amounts or ultrasonic time, and to define test specifications for the respective part/component.

For decay measurements, the extraction process will be repeated six times, in an identical manner, with the same part/component.

The decay curve graphically illustrates if and how particle quantity and weight change after each part/component sampling. Ideally, the curve will go down below the 10% mark, thus indicating a successful decay measurement process.

The process is conducted as follows:

  1. blank value determination of all components required for extraction and testing
  2. determination of a suitable extraction method and the number of inspection lots
  3. six testing cycles with each inspection lot, with identical starting parameters, on a separate filter membrane per testing cycle
  4. analysis of the six filter membranes in the order of sampling
  5. evaluation of particle number and weight (gravimetric analysis) in a calculation program
  6. The decay curve will be considered successful, if the accumulated value of the six samplings is < 10 %. Unless this is the case, the decay measurement will have to be repeated with a new inspection lot and respectively adapted extraction parameters.
  7. In case the decay measurement is successful, the extraction parameters will be recorded until the < 10 % mark is reached, as they represent the standard analysis for this particular part/component. Example:
    • starting parameter per decay measurement:
      extraction medium 2 litres, extraction volume flow 1.5 l/min, extraction nozzle Ø 2.5 mm, value < 10 % at 5th decay measurement
    • extraction parameters for standard analysis: 4 x 2 litres at 1.5 l/min and a Ø 2.5 mm nozzle = 10 litres and 1.5 l/min

Would you like to find out more about our services?
We will be pleased to assist you.


SLE Technology GmbH i. L.

Josef-Buchinger-Strasse 9
94481 Grafenau

SLE Headquarters

Tel.: +49 (8552) 9640 0


SLE Service

Tel.: +49 (8552) 9640 52

SLE Sales

Tel.: +49 (8552) 9640 21