INSPECTION , TESTING & MEASUREMENT
The table below demonstrates typical applications for both magnetic induction and eddy current methods . We also extensively talk about magnetic induction and eddy current measurement principles in the “ How to Measure Coating Thickness ” article .
Substrate ( Base Material )
The main field of applications
Magnetic Induction
Ferromagnetic ( e . g ., Steel or Iron )
- Non-ferromagnetic coatings
- Electroplated coatings made of chromium , zinc , copper or aluminium
- Paint , enamel , varnish or plastic coatings
Table 1 : Measurement principles and their main applications
Eddy Current
Electrically conductive non-ferrous metal ( e . g ., Aluminium )
- Electrically non-conductive coatings
- Paint , enamel , varnish or plastic coatings
- Anodic coatings
Helmut Fischer GmbH offers a wide range of DFT gauges with built-in or interchangeable probes that use magnetic induction and eddy current methods . Learn more about the instruments we suggest following the link : https :// fischerinstrumentation . co . uk / privacy-policy / product-portfolio / dry-film-thickness-gauge-fmp /
FD13H probe . Probes for measurements on virtually all metals . The probes work with two test methods and are therefore able to measure coating thicknesses on non-ferrous metals as well as on ferrous metals . Because of the large pole tip , the probes are also well suited for measurements on rough surfaces .
FTD3.3 probe . This probe utilises the eddy current method . It is suitable for measurements of rough paint , lacquer , plastics , and anodised coatings on Non-ferromagnetic substrates .
V7FKB4 probe . Measures non-ferrous and non-metallic coatings on steel or iron substrates . Higher repeatability precision than single tip probes when measuring rough surfaces .
FKB10 probe . Measures non-ferrous and non-metallic coatings on steel or iron substrates . Uniquely suited for thick layers ( up to 8mm ).
Provide a much higher measurement precision on rough surfaces than single tip probes .
Table 1 : Probes for measurements on rough surfaces
The above probes work with the FMP family of instruments .
Coating roughness
If a coating is rough , then there will be a higher variation in the measured coating thickness . It happens since a probe tip may rest on peaks or in troughs . Probes that aren ’ t influenced by rough coatings solve this challenge Figure 2 .
Wide and dual-tip probes have a larger measurement area and
Figure 2 . A schematic diagram demonstrating how peaks and troughs affect coating thickness readings [ A ] and the effect of wide and dual-tip probes that take consistent readings on rough surfaces [ B ].
always sit on peaks . This way , the total thickness of a coating is consistently measured . A list of probes offered by Helmut Fischer GmbH , specifically designed to measure on rough surfaces consistently , can be found in table 1 :
The location of the measurement area
The location of the measurement area also plays a significant role in selecting the right DFT gauge for the job . When it comes to testing coating thickness on flat surfaces , most of the time , it ’ s possible to get away with a standard instrument setup .
CONTINUED ON PAGE 56
LIVE Revised dates : 12th & 13th May 2021 , NEC , Birmingham
- we have everything covered
Surface World Live is being held at the NEC in Birmingham on the 12th & 13th May 2021 . Fischer look forward to seeing you at the show !
Your industry under one roof over two days .
twitter : @ surfaceworldmag SEPTEMBER 2020
55