Surprisingly, the idea of magnetic particle inspection dates all the way back to the 1930s. Since then, it has been a mainstay in the NDT industry. However, with such a long history come a number of misunderstandings. As a leading provider of MPI, we want to take a closer look at some of them.
MPI is suitable for all metals
It is amazing how many people think this type of testing will work on any kind of metal. In truth though, it is generally only appropriate for metals that can be magnetised. That includes ones like iron and nickel, as well as a number of alloys that contain them such as types of steel.
It helps to use more current
Some people incorrectly think that using more current will help to reveal imperfections. However, this is not always the case. What you need to think about is a higher current can make fluorescent particles attract to the entire part. This brighter background can saturate everything and make it harder to spot flaws.
Magnetising is always the same
It is easy to see why people think parts will magnetise the same when they look similar. However, different metals will have their own levels of permeability and retentivity. That means you always need to check the material and adapt the magnetic particle inspection to suit it.
It is not important to clean parts before testing
Sadly, skipping this vital part of preparation can affect the results. Contaminants on the surface of the part can make it harder to detect issues. It can also contaminate the bath, meaning it will require changing. To maximise the chance of detection, always clean parts.
Using more particles helps
Similar to using more current, this can also make it harder to spot defects. What will happen is the higher amount of particles will mean the concentration on the background is too high. What you should do instead is add particles slowly until you get the right concentration.
Choose us for magnetic particle inspection
Format NDT Ltd is a company with an excellent reputation. We always strive to offer the most accurate MPI. To do this, we ensure our team have the right training and know how to set up equipment properly.
If you need to arrange testing, contact us.