Experience of Developing Instruments for Measuring Firearm Functional Coating Thickness

Abstract

The paper deals with the task of measuring the thickness of various functional non-ferromagnetic coatings, used in firearm manufacturing. In order to achieve the goal, the magnetic induction method for measuring the coating thickness is proposed. The paper identifies the main sources of errors, related to external factors and measurement object unique features affecting the measurement results. Specifically, it was revealed that the measurement results are significantly impacted by the geometry of the test object related to the diameter of the transducer measuring zone, allowing to formulate the criteria of optimizing its geometric parameters.

The paper gives the results of optimizing the primary measuring transducer geometric parameters ratio and the dependence, allowing to determine the transducer measuring zone diameter for the predefined thickness range.

Transducer excitation with nonharmonic electromagnetic field and using the induced electromotive force area as the primary informative signal and clocking of the conversion cycle with reference to mains voltage frequency gives the opportunity to exclude coating and base electric conductivity effect on measurement results, to increase the measuring instrument immunity to interference, time and temperature stability as well as to use the wear-resisting alloy steel as a transducer core material.

The totality of the proposed solutions allowed to develop a thickness gauge with the miniature measuring transducer to use in Kalashnikov enterprises serial production with non-destructive thickness testing of various functional coatings of small-sized and geometrically-complex parts for modern and advanced firearm types.