TESTING & MEASURMENT
Thickness of protective layers in aluminium cans and tubes
Aluminium tubes and cans are a commonly used as packaging for pharmaceutical , cosmetic or even food products . In order to prevent direct contact and chemical reactions between the container and the contents , the tubes are usually coated inside with a protective polymer layer . The thickness of the coating must be monitored regularly during the application process to ensure the proper function of the protective lining .
Coating Thickness Measurement of Tube Coatings for Quality Assurance
For aluminium cans and tubes filled with pharmaceuticals or food , the inner protective layer is critical for preventing chemical reactions between the packaging and the contents ; this is why its thickness must be monitored carefully during manufacture . For quality assurance , random samples are periodically removed from the running production process and their linings are measured using the eddy current testing method . However , care and skill are required : these protective coatings are particularly sensitive to pressure . A “ normal ” probe can easily compress the layer , thus leading to incorrect measurement results .
After being cut , the samples are shaped to form a flat metal strip . For the measurement itself , FISCHER ’ s probe FTA2.4-SC is ideally suited because of its large contact area and spring-mounted measuring element , which exerts only low contact pressures . The stand V12 guarantees precise vertical guidance and controlled vertical touchdown . The probe can be operated and the results evaluated by the handheld measuring devices from the FISCHER FMP series .
Eddy current probe FTA2.4-SC , attached to the stand V12 , measuring a protective layer inside an aerosol can made of Aluminium .
The Automated Solution for High Quantities
For processing larger sample quantities , an automated solution is also available with the FISCHERSCOPE ® MMS ® PC2 and a motorised , programmable stand . In addition to the inner protective layers , the outer skins and coatings can also be measured with these devices .
38 MAY 2021 read online : www . surfaceworld . com