Particle normal
A particle standard is understood to be an object contaminated with metallic particles in a fixed number and size distribution, which is used in the area of " technical cleanliness " according to VDA 19 and ISO 16 232. The particle standard is thus an object that has been specifically contaminated with standard particles.
description
There are basically two types of particle normals. On the one hand, the particle standard for microscopy, where the particles are only printed on. It is only used to qualify the measuring system. On the other hand, the particle standard in which real particles are applied, which detach from the particle standard during the extraction of a cleanliness test and in this way enter the process of the cleanliness test. Such a particle standard is used, among other things, to determine the recovery rate of test particles in accordance with VDA 19 Part 1, testing technical cleanliness - particle contamination of functionally relevant automotive parts. The following four steps are usually required to qualify a cleanliness test:
- Blank value determination,
- Particle standard to determine the recovery rate of test particles,
- Decay examination,
- Microscopy particle standard.
Incorrect handling or an error in the extraction unit can often lead to the loss of a large number of particles relevant to the result when carrying out cleanliness tests. The blank value determination provides information about the extent to which the result of a cleanliness test is falsified by irrelevant, externally supplied particles. On the other hand, the particle standard for determining the recovery rate of test particles provides information on whether all the particles relevant to the result that originate from the component to be tested are fully recorded.
The particle standard thus enables the qualification of the entire process flow of a cleanliness test from extraction to the rinsing procedure, drying of the filter, handling and microscopic evaluation. There are two possible uses: a) Determination of the recovery rate with the help of test particles (standard particles) produced in a defined manner, which are located on the particle standard, B. come from a backwashed fabric filter. When using a particle standard which is covered with test particles produced in a defined manner, the recovery rate must be 100%. This enables a clear qualification. When using in-house house particles, the recovery rate can vary. As a result, the qualification is hardly reproducible. The decay investigation can be used to ensure whether the selected extraction parameters are suitable for a specific component and the microscopy particle standard ultimately enables a statement to be made about the capability of the measuring microscope.
history
The particle standard for qualifying cleanliness tests was developed in 2012 by a company founded specifically for this purpose. The reason for the development of the particle standard was the non-expedient deviations in the results of cleanliness tests in cleanliness laboratories that were independent of one another. Up until then there was no standard for the procedure or for the technical monitoring of the equipment necessary for carrying out a cleanliness test.
With the revision of VDA 19 from 2013, the particle standard or its application was included in VDA 19 under the name "Recovery of test particles". In 2014 the particle standard was awarded first place in the Fraunhofer purity technology award “Clean2014”. The number of users increased by leaps and bounds as a result of the publication. Today the particle standard is an integral part of the qualification of cleanliness tests in many cleanliness laboratories. Once a year, a round robin test is carried out to determine the recovery rate of test particles with the help of the particle standard. Almost all German and now international automobile manufacturers and their suppliers are represented among the participants.
Individual evidence
- ↑ VDA QMC: VDA 19 part 1, testing of technical cleanliness . Ed .: VDA QMC.
- ↑ CLEAN! 2018 - Fraunhofer Purity Technology Award. Retrieved December 23, 2017 .
- ↑ Normpartikel - Press / News. Retrieved December 23, 2017 .
- ↑ VDA 19 part 1, testing of technical cleanliness
- ↑ VDA 19 Part 2, Technical cleanliness in assembly
- ↑ ISO 16 232, Road vehicles - Cleanliness of components of fluid circuits