AC200v Coil Flaw Magnetic Crack Detector Magnaflux

magnetic coil flaw detector magnaflux magnetic particle test equipment

I. main parameter

1, Input current: 8A, determined according to the set values of magnetization and demagnetization, the standby current is 0.5A;

2, Power supply: AC200-240V 50 / 60Hz;

3, Magnetizing current: 8A (8A * 400T = 3200AT);

4, Central magnetic field: Max 110Gs;

5, Demagnetization current: 8-0A;

6, Coil size: Φ 300mm, 400 turns in total;

7, Temporary load rate: > 30%;

II. Function introduction

1, Magnetization - start the electromagnetic field to magnetize the workpiece;

2, Demagnetization - demagnetization field starts to demagnetize the workpiece;

3, Over temperature alarm - the coil has a built-in 75 ℃ temperature sensor. When the set temperature is exceeded, it enters the protection state;

III. Installation and commissioning

Installation:

1. The equipment shall be installed in a dry environment without metal dust, corrosive gas and inflammable and explosive articles;

2. The temperature of surrounding medium shall not be lower than - 10 ℃ and not higher than + 40 ℃;

3. The relative humidity of the air shall not be greater than 85%;

4. The pipe and wire connection between the installation equipment and each auxiliary facility shall be connected according to the indication sign and plug base;

5. Power supply (power supply, air source, etc., according to equipment installation environment and operation conditions), and the equipment shell is reliably grounded;

Commissioning:

1. After the equipment is installed in place, first check whether all connecting wires and fastening screws are loose and fall off;

2. Use instruments to measure whether the voltage at the upper end of the main switch of the machine meets the requirements of equipment installation environment and operation conditions;

3. Check each function action, manually press or toggle each function switch, and each function action of the equipment shall be executed accordingly;

4. Demagnetization effect inspection: check whether the residual magnetism after demagnetization meets the requirements;

5. After passing the commissioning and inspection, the equipment can be put into production.

IV. Routine maintenance

After the equipment is used, the following operations must be carried out:

1. Turn off the power switch and cut off the power supply of the equipment;

2. Cut off the main switch of external power supply;

3. Clean up the oil stain on the coil surface and keep the whole equipment clean;

4. Check the circuit connecting line, cable and fastener for looseness and aging within one month;

5. Check whether the concentration of magnetic suspension meets the standard every day;

6. Neutral washing must be used to clean the oil stain on the surface of the equipment;

7. If the shell is damaged, it is forbidden to continue to use;

V. Flaw detection principle

Principles of electromagnetism

The magnetizing current forms an electromagnetic field through the surface of ferromagnetic workpiece (AC and half wave DC have skin effect). The existence of defects will cut off the magnetic line of force, form a leakage magnetic field and adsorb magnetic particles. Magnetic particles accumulate to form magnetic marks. The existence of defects can be judged by observing magnetic marks (magnetic marks are actually enlarged defects).

Longitudinal magnetization method

That is, using the coil method, the workpiece is threaded into the coil or placed between the magnetic yoke composed of two coils. When current is applied to the coil, the longitudinal magnetic field is generated in the coil and passes along the long axis of the workpiece to check the circumferential crack.

Residual method

Different from the continuous method, the workpiece is magnetized first, then soaked in magnetic suspension for a period of time, and magnetic particles are absorbed by the remanence of the workpiece to form magnetic marks. This method is limited to low requirements, single-direction and residual magnetic induction intensity of the workpiece Br≥ 0.8t.

Remanence refers to the size of the remaining magnetic field after flaw detection, usually in Gauss (Gs), millitesla (mT), ampere/meter (A/m) as the unit. 1mT=10Gs,80A/m=1Gs, the size of remanence is related to the workpiece material.

Magnetic suspension (magnetic powder should be fully stirred and suspended in the liquid before flaw detection.)

Magnetic powder is processed to reach a certain grain size requirements of iron powder. General magnetic particle flaw detection wet method can be more than 400 mesh.

Fluorescent magnetic powder is in ordinary magnetic powder plus a chemical substance, usually called fluorescent brilliance agent, added after the fluorescent lamp irradiation can emit fluorescent light, can increase flaw detection sensitivity, convenient observation.

Oil-magnetic suspension formula :(or 3# oil-based magnetic powder flaw detection carrier)

(winter) transformer oil (25#) : odorless kerosene = 1:3

(summer) transformer oil (25#) : odorless kerosene = 1:2 -- 1:3

Mixed oil: ordinary non-fluorescent magnetic powder =1000ml: 10-20g

Mixed oil: fluorescent magnetic powder =1000ml: 2g-3g

Water magnetic suspension formula: compound water-based fluorescent magnetic powder with a small amount of water to stir the magnetic powder into paste, then add enough water (compound suspension powder has contained dispersant, defoaming agent, rust inhibitor components), non-compound fluorescent magnetic powder ratio is as follows;

dispersant 21g Rust inhibitor 21g

Defoaming agent 21g Fluorescent magnetic particle 2g—3g

Water 1L

Sensitivity

Sensitivity refers to the precision of magnetic particle flaw detection, usually through the NATIONAL standard TYPE A test to detect. Type A standard test is usually referred to as sensitivity test. Type A standard test sheet has three kinds of sensitivity: high, medium and low. The smaller the fraction value in type A, the higher the effective magnetic induction intensity that can display magnetic mark is required. (A-15/100, A-30/100, A-60/100, A-7/50, A-15/50, A-30/50, six scores, the highest sensitivity of 1# test film includes A-15/100, A-7/50. 2# Test tablets have moderate sensitivity, suitable for most industries, including A-30/100, A-15/50. 3# test tablets have the lowest sensitivity, including A-60/100 and A-30/50.)

Method of use of standard sensitivity test piece (suitable for continuous method), usually using type A standard test piece 2#(30/100 or 15/50) for the selection of magnetization current for flaw detection.

The artificial defects can be clearly displayed on the smooth surface of the test piece by tightly fitting the surface of the test piece with artificial defects with the workpiece under test, slowly flowing magnetic suspension through the workpiece and applying appropriate magnetization current (adjusting circumferential direction and longitudinal direction respectively). The value of magnetization current is the appropriate magnetization specification.