NDT ( NON DESTRUCTIVE TESTING )

NDT (NON DESTRUCTIVE TESTING) :-

Non Destructive Testing in great variety are in world wide used to detect variations in structure,minute changes in surface finish, the presence of cracks or other physical discontinuities,measure the thickness of materials and coatings and to determine other characteristics of industrial products.

REASON'S FOR THE USE OF NDT:

"NDT" is used by the manufacturers for the following reasons:

1. To ensure product reliability.

2. To make profit for the user.

a) To ensure customer satisfaction

b) To aid in better product reliability.

c) To control the manufacturing processes.

d) To lower the manufacturing costs.

e) To maintain uniform quality level.

SOME OF THE MOST COMMON NDT METHODS ARE :

1.VISUAL INSPECTION

2.LIQUID PENETRATION TEST

3.MAGNETIC PARTICLE TEST

4.RADIOGRAPHY TEST

5.ULTRASONIC TEST

FILLET WELD FRACTURE TEST

FILLET WELD FRACTURE TEST Object : To break the joint through the weld to permit examination of the fracture surfaces for flaws and to check root penetration and fusion. Method: The specimen is cut to length and a saw cut, normally 2 mm deep, is made along the center of the weld face. The specimen is fractured by bending or hammer blows. Reporting Results: Thickness of parent material. Throat thickness and leg length. Location of fracture. Appearance of joint after fracture. Depth of penetration / lack of penetration or fusion.

CHARPY V NOTCH IMPACT TEST

CHARPY V NOTCH IMPACT TEST Object : To determine the amount of energy absorbed in fracturing a standardized test piece at a specified temperature. Method : A machined, notched specimen is broken by one blow from a pendulum. Because scatter occurs in the results, at least three specimens are used to assess the joint represented. Testing is carried out at a temperature specified in the appropriate application standard. Reporting Results: Location and orientation of the notch. Testing temperature. Energy absorbed in joules. Description of fracture appearance. Location of any defects. The Charpy impact test, measured in joules, is an assessment of TOUGHNESS. Transition temperature (curve) in steel.

Part - 6 Most commonly asked Mechanical Interview Questions with answer

Most commonly asked Mechanical Interview Questions 1. Why Entropy decreases with increase in temperature? Ans. ds=dQ/T Entropy is inversely proportional to the temperature so, as temp. Increases, entropy decreases. 2. Why different types of sound are produced in different bikes, though they run on SI Engines? Ans. Engine specifications are different in different manufactures like as Bore Diameter (CC), Ignition timing. Also the exhaust passage takes more responsible for sound. 3. How much Watt means 1Hp? Ans. 746.2 Watt 4. Explain Bicycle Rear Wheel Sprocket working? Ans. Rear wheel sprocket works under the principle of ratchet and pawl. 5. Definition of Octane Number and Cetane Number? Ans. Octane No.- Octane number is defined as the percentage, by volume, of iso octane in the mixture of iso octane and h-heptane. It is the measure of rating of SI engine. Cetane No.- Cetane number i

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