Level 1 Theory Flashcards
Iron, Nickel, and Cobalt are what
Materials that magnetic particle inspection can be performed on
Reluctance
The opposition that a ferromagnetic material shows to the establishment of a magnetic field
What are several advantages over liquid penetrant inspection that Magnetic particle inspection has
Components with thin coatings can be inspected without removing the coating and can be inspected more rapidly
A hysteresis loop
Shows the relationship between the Induced magnetic flux density and the magnetizing force
Residual magnetism
The magnetic flux density that remains in the material when the magnetizing force is zero
Domains
Small polarized regions that make up Ferromagnetic materials
What never cross each other
Magnetic lines of force
A material with a wider hysteresis loop has
Lower permeability Higher retentivity Higher coercivity
What forms closed loops from pole to pole
Magnetic lines of force
Direct current
type of current flows continuously in one direction at a constant voltage
What is a circular field
A magnetic field induced by a current carrying conductor
What is A magnetic pole
A location where a magnetic field can be detected exiting or entering a material
What is sometimes restricted to use for potential of arcing that could damage parts
Prods
When testing parts with magnetic particles, it is best to magnetize the part how
In two directions at right angles to each other
Why are all materials affected in some way by a magnetic field
Because all matter is composed of atoms
When does the best detection of defects occur
When the lines of magnetic force are perpendicular to the longest dimension of the defect
What is A magnetic field
A volume of space where there is a change in magnetic energy
When is a material considered demagnetized
When its residual magnetic field measures less than 3 gauss
A material with a Higher permeability has a what
A narrower hysteresis loop
Components generally must be demagnetized because residual magnetism can what
Increase wear by attracting abrasive particles, Affect machining and welding processes, or Interfere with near by electronic components
Faraday’s Law of Magnetic Induction
The magnetic forces of the material’s electrons will be affected by an external magnetic field
High residual magnetism is found in what material
A material with a wider hysteresis loop
Magnetically saturated
When all the magnetic domains are aligned
Direct induction needs
Good electrical contact must be established between the test equipment and test component
When the magnetizing current is stopped, a ferromagnetic material will what
Retain a residual magnetic field withing the component
Permeability
Describes the ease with which a magnetic flux is established in a component is called
Coercive force
The amount of reverse magnetic field which must be applied to a magnetic material to reduce the magnetic flux to zero
It is easier to measure a longitudinal field when
When using both a circular and longitudinal magnetic field
When a ferromagnetic material is in a unmagnetized state, the domains are
Randomly organized
What establishes a magnetic field that extends from the ID to the OD of a circular part
The circular conductor technique
Magnetic flux density
The number of magnetic lines of force cutting thorugh a plane of a given area at a right angle
When performing a magnetic particle test with a coil, the part should be placed where
Along the inside edge of the coil
Ferromagnetic
Has a large susceptibility to magnetic field
A yoke establishes a magnetic field
Between the north and south poles of the yoke
A circular magnetic field has lines of force that run where
Circumferentially around the perimeter of the part
What happens when a magnetic field cuts across a crack
Magnetic poles form at the edges of the crack
Dipole
An object that has a magnetic pole on one end and a second equal but opposite magnetic pole on the other
Iron filings
small magnetic particles used in magnetic particle inspection
Higher permeability, Lower retentivity, and Lower coercivity are components of what
Narrower hysteresis loop
Are dry magnetic particles one color, non-reusable, or one size?
Non-reusable
You will find subsurface or surface indications with magnetic particle testing
Subsurface
Diamagnetic materials
Have a very weak and negative susceptibility to magnetic field
Multidirectional inspection equipment does what
Reduces inspection time
A material with Higher reluctance has a what
A wider hysteresis loop
Coercive force
The force required to remove the residual magnetism from the material
The magnetic field circling each loop of wire in a coil combines with the fields from the other loops to produce a concentrated field
Down the center of the coil
A material with Lower coercivity has a what
A narrow hysteresis loop
Whats the purpose of heating materials above their curie temperature or reversing and decreasing magnetic field
Demagnetized
North Pole
The area where the exit poles are concentrated
A longitudinal magnetic field has magnetic lines of force that run
Parallel
