Crack depth meter 281M-C electro potential

281M–C Crack depth meter manufactured by Mashproject LLC is a high precision device designed to measure the crack depth on the surface of metal parts. The device ensures measurement the depth of cracks coming to the surface of products made of ferromagnetic and non-ferromagnetic materials as well as aluminum.

Registered in the Russian State Register of Measuring Instruments, certificate No. 92789-24.

281M–C Crack depth meter implements the electric potential method on alternating current, which allows fast and accurate measurement of crack depth from 0.5 to 100 mm. The current electrodesare used to pass the direct current with a frequency of 1 kHz in the area of the measured defect. The voltage resulting from the passage of current along the walls of the defect is proportional to the defect depth and is determined using receiving electrodes and an electronic unit.

The device is particularly effective when used in combination with productive crack detection methods: magnetic particle inspection, dye penetrant inspection, Eddy current and other control methods.

Main features of 281M–C Crack depth meter

• New shock-resistant dust- and moisture-proof housing.
• Possibility of creating additional configurations and calibrations based on customer specimens.
• Bright color display with high contrast facilitates reading the measurement results.
• Possibility to organize a data archive as named blocks of measurement results, with subsequent data transfer to PC for processing.
• Special software for processing data on a PC.

Test objects:

— shafts, rolls, rolling mills;
— pipes, pipelines, oil and gas pipelines;
— pressure vessels;
— energy production facilities;
— parts of structures, machines and mechanisms

Operation advantages of 281M–C Crack depth meter

• Shock-proof case ensures safe protection of the equipment.
• KO-281 Reference block of defect models (certificate No. 84019-21 in the Russian State Register of Measuring Instruments) made of material selected by customer (ferromagnetic, non-ferromagnetic or aluminum) included into delivery set.
• Movable spring-loaded electrodes optimal for measurements on curved and uneven surfaces.
• Setting control limits, visual indicating when the measurement result exceeds the limits.
• Signal averaging when taking “zero” readings ensures a stable and accurate measurement result.
• Control of products made of ferromagnetic and non-ferromagnetic materials.
• The device memory contains Scales for magnetic steels (C20E2C), austenitic steels (X10CrNiTi18-10), aluminum alloys (AlCu4Mg1).
• Wide measurement ranges from 0.5 to 100.0 mm.
• Low influence of electromagnetic properties of the material on the measurement result.

Probes for 281M–C Crack depth meter

Probe scheme	Type	Design	Crack depth measurement range	Features
	«1х4»	4 electrodes in 1 row	0.5 – 30 mm	The most universal probe. Included into standard delivery set.
	«2х2»	4 electrodes in 2 rows	0.5 – 20 mm	Designed for work in hard-to-reach places (thin shafts, fillet transitions) and surfaces with closely spaced cracks
	«3+1»	4 electrodes: 3 electrodes in 1 row and 1 external electrode	0.5 – 30 mm	Probe with external current electrode for control of products made of ferromagnetic materials (steel, cast iron). Most often used for control of deep cracks.

281M-C Crack depth meter complies with the requirements of the technical regulations of the Customs Union TR CU 020/2011 “Electromagnetic compatibility of technical equipment”.
The QMS of Mashproject LLC complies with the requirements of GOST R ISO 001-2015 (ISO 9001:2015) in relation to the production of devices.

281M-C Crack depth meter is designed carrying out measurements in the field conditions as well as in shop and laboratory.

Requirements to controlled item:

• Roughness of controlled surface is at least 1.6 Rz.
• Stable electrical contact with the probe electrodes.

Preparation for measurements using the 281M-C Crack depth meter

1) Before each use of the device, it is necessary to check its functionality using reference block.

If measurements are carried out on materials with electromagnetic properties that differ significantly from the material of the reference block used in setting up the device, it is necessary to manufacture an additional reference block with a crack corresponding to the upper limit of the expected crack depth and adjust the device.

The adjustment is saved for the entire service life of the Crack depth meter and can be changed by user at any time.

2) To ensure electrical contact it is  MANDATORY to grind the following areas of reference block/ controlled product:

• a defect-free area (to take “zero” readings)
• a controlled area with crack.

Crack length measurement is carried out in two steps:

Step 1.
The first stage involves measuring the current flowing in a defect-free area located away from the crack.

— Measurements using “1×4” and “2×2” transducers are carried out on a free section of the productr away from the crack at a distance of at least of 10 mm from the nearest electrode.

— The first current electrode of the “3+1” converter must be located at a distance of at least of 60 mm from the crack, and the nearest receiving electrode must be located at a distance of 10-15 mm from the crack.
At the end of Step 1, the device is auto-calibrated for the current flowing through the crack.

It is highly recommended to repeat Step 1 several times to ensure the stability of readings as they largely determine the measurement accuracy.

Step 2.
The second stage involves measuring the crack depth, with the receiving electrodes located on both sides of the crack edges.

The crack depth (in millimeters) is displayed on the screen.

Accessories:

• “2×2” probe
• “3+1” probe
• Defect models test block KO-281
• Cordless grinding machine for preparation of control zone on the product surface