I. Basic Principles of Magnetic Particle Inspection (MPI):
1. Explain the principles of magnetic flux and magnetic field lines. (Focus on how these relate to detecting discontinuities.)
2. Describe the difference between longitudinal, circular, and longitudinal/circular magnetization. Include how each is achieved and the type of discontinuities best detected by each.
3. What are the advantages and disadvantages of using DC, AC, and half-wave rectified current for MPI?
4. Explain the concept of magnetic field saturation and its importance in MPI.
5. Describe the different types of magnetic particles used in MPI (e.g., wet, dry, fluorescent, visible). Include their advantages and disadvantages.
6. Explain the purpose and importance of demagnetization. Describe different methods.
7. Define permeability, retentivity, and coercivity. How do these properties relate to the materials inspected using MPI?
8. Explain the effects of material composition, geometry, and heat treatment on the magnetizing process.
9. What are the limitations of MPI? What types of discontinuities are difficult or impossible to detect with MPI? (e.g., subsurface defects in non-ferromagnetic materials)
10. Explain the importance of proper part cleaning and surface preparation before MPI.
II. Equipment and Procedures:
1. Describe the different types of MPI equipment (e.g., yokes, prods, coils, AC/DC power supplies). Include their applications and limitations.
2. Explain the procedures for conducting wet and dry MPI inspections.
3. Explain the proper techniques for applying magnetic fields to different part geometries. (Consider complex shapes.)
4. Describe the interpretation of magnetic particle indications. Differentiate between relevant and non-relevant indications.
5. How do you determine the amperage required for proper magnetization?
6. Explain the importance of using proper technique to avoid false indications.
7. Explain the process of documenting MPI inspections (including photos, sketches, and reports).
8. What safety precautions must be taken when performing MPI? (e.g., electrical safety, eye protection, etc.)
9. Describe different techniques for detecting surface and near-surface discontinuities.
10. Explain the difference between continuous and residual magnetization methods. When is each appropriate?
III. Interpretation and Reporting:
1. Differentiate between surface and subsurface discontinuities based on MPI indications.
2. Explain the criteria for accepting or rejecting a part based on MPI results. (Reference acceptance standards.)
3. How do you assess the severity of a discontinuity based on its length, width, and depth?
4. Describe the process of writing a comprehensive MPI inspection report. What information needs to be included?
5. Interpret various magnetic particle indications (drawings of indications and their interpretations will likely be part of the exam). This section requires strong visual interpretation skills.
6. Explain the impact of different factors on MPI indication appearance (e.g., discontinuity orientation, current type).
IV. Codes and Standards (specific codes vary by region):
1. Familiarity with relevant codes and standards related to MPI (e.g., ASTM, ASME, etc.). Know the specific standards relevant to the type of work you will be performing.
Remember that these are sample questions. Your actual exam will likely be more specific to your training and certification body. Study your course materials thoroughly, practice interpreting indications, and familiarize yourself with relevant codes and standards. Good luck!