Page 101 - EEA QM Edition 6

Quality Requirements Edition 5.0 European Enamel Association

8.4 Enamel powder for the electrostatic application on sheet steel 8.4.1 Testing of powder fineness

The parameters of a powder affecting its workability in the enamel shop are residue of pow- The particle size distribution and especially the share of grains > 60 μm in powder
der, fluidity, electrical resistance as well as adherence of the powder on the sheet steel after enamels affects the application properties in the enamelling shop. It can be determined by
electrostatic application. They are to be registered in the laboratory and to be reproduced the known PRINCE test sieve (screen aperture 0.06 mm = 60 μm = 10000 mesh/cm ).
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within quantitatively acceptable limits.
The residue of the powder in percentage by weight is a measure for the frequency of the
The following standard data have proved to be characteristic for an electrostatic powder: particles > 60 μm.

- Residue of powder RP > 40μm in % The figures can be reproduced up to an exactness of ± 0.5%. With laser or XRF-methods –
- Fluidity of powder FP in g/s also used for the production control of powder enamels – a complete granulometric analysis
- Short time powder adherence STPA in % including statistical information (d50, standard deviation) can be obtained.

- Surface resistance of powder SRP in Ω cm
(the resistivity is mostly determined in Ω cm)

From instrumental and external influences cleared measuring data is condition of a basic
research in the field of electrostatic powder application as well as quality control in the plant
and information concerning the powder behaviour in the enamel shop.

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