Description: A magnet that induces a magnetic field in the area of a part that lies between the poles. Yokes may be permanent magnets or electromagnets. Permanent Magnet Yoke – A body which possesses the ability to retain or hold a large amount of the applied magnet field after the active power of the field is removed.
What is a magnetic yoke?
A magnetic Yoke is a portable device for detecting surface and sub-surface cracking in any ferro-magnetic material.
What is the basic principle of magnetic particle testing?
The magnetic particle test method of Non-Destructive Examination was developed in the USA, in the 1930s, as a way to check steel components on production lines. The principle of the method is that the specimen is magnetised to produce magnetic lines of force, or flux, in the material.
How do you test magnetic particles?
Magnetic Particle Inspection is performed in four steps:
- Induce a magnetic field in the specimen.
- Apply magnetic particles to the specimen’s surface.
- View the surface, looking for particle groupings that are caused by defects.
- Demagnetize and clean the specimen.
What is a magnetic particle test used for?
Magnetic Particle Testing (MPT), also referred to as Magnetic Particle Inspection, is a nondestructive examination (NDE) technique used to detect surface and slightly subsurface flaws in most ferromagnetic materials such as iron, nickel, and cobalt, and some of their alloys.
When would you use the coil to magnetize?
The use of coils and solenoids is a third method of indirect magnetization. When the length of a component is several times larger than its diameter, a longitudinal magnetic field can be established in the component.
Is standard for magnetic particle inspection?
Magnetic particle users outside the aerospace industry have typically used ASTM E709 Standard Guide for Magnetic Particle Testing as their baseline standard for procedures. ASME, AWS, and API standards all use ASTM E709 as a reference to build their specific requirements.
What is the basic magnetic principle?
All magnets have a north pole and a south pole. Like poles repel but opposite poles attract each other. … The magnetic force flows from the north pole to the south pole of the magnet. Connecting the north pole to the south pole of a different magnet (or vice versa) makes all the electrons spin in the same direction.
What materials can you use for magnetic particle inspection?
Because this method relies on a magnetic field to produce results, it works best on ferrous materials, like nickel, iron, cobalt, and some alloys. Components like billets, bars, castings, forgings, fasteners, weldments and extrusions are also commonly tested using magnetic particle inspection.
What are the limitations of magnetic particle testing?
Disadvantages of the Magnetic Particle method of Non-Destructive Examination are:
- It is restricted to ferromagnetic materials – usually iron and steel, and cannot be used on austenitic stainless steel.
- It is messy.
- Most methods need a supply of electricity.
Can you magnetic particle inspect stainless steel?
It is true that you can perform mag particle testing on ferritic stainless steels. The easiest method of determining if the material can be mag particle inspected is to see if a permanent magnet is attracted to it. The three elements which are ferromagnetic are iron, nickel and cobalt.
What method of magnetic particle inspection is used most often to inspect aircraft parts for minute or invisible cracks?
Eddy current inspection. What method of magnetic particle inspection is used most often to inspect aircraft parts for invisible cracks and other defects? Continuous.
What happens when a magnetic field cuts across a crack?
A crack which cuts across the magnetic field attracts the magnetic particles to form an indication which may indicate a defect. Current is passed around the part parallel to the defects to be found.
Can MPI be done on painted surface?
The thicker the paint, the less sensitive the test. That being said, magnetic particle testing over paint can work very well. Magnaflux even makes contrast paint to be used with magnetic particle testing.
Can you MPI Aluminium?
MPI equipment will only work on Ferromagnetic materials. Titanium, Nickle, Stainless Steel, Monel and Aluminium CANNOT be tested with MPI. You need to use Penetrant technique for that. … Any trained operator should know that MPI will not test the materials you mention in your message.
What is PT test in welding?
Liquid Penetrant Testing (PT) is used to detect casting, forging and welding surface defects such as hairline cracks, surface porosity, leaks in new products, and fatigue cracks on in-service components.