Techshore Inspection Services-Kochi-official blog of Techshore Kerala: TECHSHORE INSPECTION SERVICES :Procedure of magnetic particle testing

SURFACE PREPARATION

The surface should be prepared in the initial step in such a way that the material surface should be grinded or machined which may mask the defects due to them. the adjacent areas and also the inspection areas should be made dry and free from lint, oil, dirt and dust which may disturb the examination. Cleaning can be conducted by several methods such as organic solvent cleaning, acid cleaning, etching cleaning etc.

TEMPERATURE CHECKING

Maintain the temperature on the test material to be inspected as 5-52 degree Celsius

APPLICATION OF IRON PARTICLE

The particles are available in dry and wet format. the dry powder usually stored in a holder is dusted off at the metal surface to provide a thin layer, any excess powder at the surface may be blowed off using a blower. The wet particles are applied by spray mode. both the particles either dry or wet are applied when the material is being magnetized.

VERIFICATION OF THE MAGNETIC FIELD

The field which is being applied is to be verified using a field indicator or a pie gauge.pie gauge made-up of steel has a total thickness of 3.25mm with a copper coating on one side, where as on the other side several lines each of a depth 0.8mm can be seen.pie gauge can be used to check the field strength and sensitivity of the magnetic field. yoke is placed parallel to any of the lines on the indicator on which the magnetic particles are dusted. then the yoke is activated and it distributes magnetic field in the indicator, then the powder is blown off. then if the powders are accumulated on the lines except the line parallel to which the yoke is placed the field direction could be confirmed and clearly defined lines of particles defines the sensitivity.

MAGNETIZING CURRENT

AC or DC current is used to spread the magnetic field

CALIBRATION

Ac or Dc mode is to be calibrated before inspection.AC mode is calibrated by placing the yoke on an iron block which weighs about 4.5 kg and lifting up and for DC mode by placing the yoke on the same block but weighing about 18.1kg and lifting up.

DIRECTION OF THE APPLIED MAGNETIC FIELD

Magnetic field is applied on the specimen .test material should be inspected in two ways yoke in such a way that the second time inspection should be totally perpendicular to the first, so that no defects are missed.

INSPECTION AND INDICATION

The defects on the specimen are to be examined and filtered according to the customer requirements.

EVALUATION

Identified defects should be examined under the acceptance standards of the applicable code section.non relevant indication are to be considered as relevant even after the surface of the material are grinded ,smoothened and still visible.

MAPPING AND RECORDS OF INDICATIONS

The defects which are identified to be relevant are to be marked using suitable markers for further repairs. the final results are recorder on MT inspection records which includes size and shape of the test material, type of magnetization ,equipment used to apply magnetic field, type of magnetic particle used and sketches indicating the coverage.

Monday, April 3, 2017

TECHSHORE INSPECTION SERVICES :Procedure of magnetic particle testing

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