[2A5] Thickness inspection of magnetic nickel coatings on ball valve mechanisms
V Syasko, P Solomenchuk, A Ivkin and A Vasilev
Constanta Ltd, Russia
The hard chemical nickel coating with the following thermal processing that
adds ferromagnetic properties to the coating is used in ball valves mechanisms
to protect the rubbing surfaces of the steel ball valves.
Traditionally, when inspecting the thickness of nickel coating ponderomotive thickness gauges are used, their permanent magnet magnetizes the nickel coating to saturation, however, the methodological limitations of the method do not allow to carry out measurements with the manufacturer's required measurement accuracy.
The completed analysis showed that the use of magneto-inductive method with the magnetization of the coating in the measurement area is promising. The induction of the technical saturation of heat-treated chemical nickel is approximately 0.6 T and for structural steels the induction of the technical saturation is in the range from 1.8 to 2.1 T. Test object 1 must be magnetized in the measurement area by magnetic field with the induction in the range of 0.6 to 1.8 T.
The source of the magnetic field can be the permanent magnet 2. To exclude the magnetic saturation of the core, a transducer with open magnetic circuit with ceramic support element 3 is used. To focus the magnetic field in the measurement area, a ferromagnetic concentrator 4 is used, simultaneously carrying out the function of partial shunting of magnetic flux of the core 5, preventing its saturation.
The results of modelling and optimization of the geometrical, electrical and magnetic parameters of the transducer, its design and application results during the output and the input thickness inspection of nickel coatings with wide range of steel ball valves during their serial production are described in detail in the paper.
Traditionally, when inspecting the thickness of nickel coating ponderomotive thickness gauges are used, their permanent magnet magnetizes the nickel coating to saturation, however, the methodological limitations of the method do not allow to carry out measurements with the manufacturer's required measurement accuracy.
The completed analysis showed that the use of magneto-inductive method with the magnetization of the coating in the measurement area is promising. The induction of the technical saturation of heat-treated chemical nickel is approximately 0.6 T and for structural steels the induction of the technical saturation is in the range from 1.8 to 2.1 T. Test object 1 must be magnetized in the measurement area by magnetic field with the induction in the range of 0.6 to 1.8 T.
The source of the magnetic field can be the permanent magnet 2. To exclude the magnetic saturation of the core, a transducer with open magnetic circuit with ceramic support element 3 is used. To focus the magnetic field in the measurement area, a ferromagnetic concentrator 4 is used, simultaneously carrying out the function of partial shunting of magnetic flux of the core 5, preventing its saturation.
The results of modelling and optimization of the geometrical, electrical and magnetic parameters of the transducer, its design and application results during the output and the input thickness inspection of nickel coatings with wide range of steel ball valves during their serial production are described in detail in the paper.
