Techshore NDT Institute is an initiative of the leading professional & reputed training brand of Techshore Inspection Services, which is having training centres all over Kerala. Techshore, offers courses in Non- Destructive Testing (NDT) from early 2015 and successful in providing placements for all those candidates in reputed companies with attractive salary packages and perks.
Techshore offers Nondestructive testing (NDT), It is a wide group of analysis techniques used in science and technology industry to evaluate the properties of a material, component or system without causing damage.
Primary Composite Structure Inspection
When selecting an NDT technique for composites, the considerations include:
Selecting the NDT technique with the physical principles that best suit the problem.
Developing suitable standards representative of the product and the inspection issues.
Developing the inspection technique for the desired sensitivity /resolution, rate, coverage, and cost.
Aircraft primary structure is the most critical and requires visual inspection and 100% instrumented NDT at the time of manufacture. Based on the physics principles of the available NDT techniques described above, UT represents the best method for primary structure laminate manufacturing acceptance. The acoustic wave from ultrasound is sensitive to the planer discontinuities that are most common. Also, the primary composite structure can easily run thicknesses of 2.5 to 35mm. Ultrasound is able to be sensitive over this range of thickness to the discontinuity size criteria that are established by the design and structural engineers.
NDT is a specification - and standards-driven technology. A " standard" will be needed that represents the product under inspection and the defective anomaly size that must be found. NDT must be run against a standard to validate the sensitivity of the equipment to the discontinuities of interest. The standard should contain representative features of the discontinuities of interest. The standard should representative features of the discontinuities that may occur during manufacturing. If an insensitive NDT instrument or technique is applied, it is possible for the bad product to pass inspection. This is a very important issue for qualifying and monitoring suppliers, their equipment, and their NDT personnel. Many specifications require repeated NDT of standards to maintain a system calibration, possibly as frequently as every four hours if the operation is not performed in an environmentally controlled facility. Ultrasound NDT standards should be developed using the manufacturing method of the product form ultimately to be inspected. This is not necessarily the case for all NDT methods.
A key issue for UT, however, is the ability to meet the inspection criteria while keeping up with production rates economically. In the early years of composite NDT, ultrasound was typically covering-0.93 to 4.6m2 (10 to 50 ft2) per hour using single -probe scanners. However, over the last 20 years, multiple transducer systems have increased speeds to hundreds of square feet per hour. More recently the development of phased array ultrasonic testing (PAUT)systems (Gaye 2012) has allowed the development of scanners capable of over 93m2 (1000 ft2) per hour coverage, depending on the part configuration. Many systems operate in the 19 to 74 m2 (200 to 800 ft2) per hour range using multiple arrays. Robotic NDT systems that utilize arrays can readily achieve over 93m2 (1000ft2) per hour scan rates.
The rate achievable and the operational cost of these systems make UT the NDT method of choice for primary structure CFRP laminates. While top scan rate coverage can be extremely high, the actual throughput of the product depends also on setup time, data interpretation time, and part disposition.
It is important to note that for secondary structures - particularly sandwich structure - and in-service inspection, the selection of the best NDT technique (based upon sensitivity to discontinuity of interest, coverage, and cost) may result in the selection of one or more of the other methods.
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 the 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 bowled 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, whereas 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. the 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 for the line parallel to which the yoke is placed the field direction could be confirmed and clearly defined lines of particles define 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
The 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 accepted standards of the applicable code section. On 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 recorded on MT inspection records which includes size and shape of the test material, type of magnetization, equipment used to apply a magnetic field, type of magnetic particle used and sketches indicating the coverage.
Techshore - Scope
The Future NDT institute offers some non-destructive testing course for Electrical Engineers, which helps them in future prospects while working in engineering and construction companies. The main methods of non- destructive testing with demonstrations include magnetic particle testing, penetrant testing, ultrasonic flaw detection, and radiographic interpretation.
Techshore - Career Objective
The title of non - destructive testing (NDT) inspector is often used interchangeably with the position titles of Nondestructive Examination (NDE), Nondestructive Evaluation (NDE) and Nondestructive Inspection (NDI). Primarily, an NDT inspector is responsible for using high-tech methods to conduct evaluations on the properties of a component, entire system, or material without causing damage.
Reference
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