- Thread starter craigten
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hotponyshoes
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Magnaglow hf14 is a simple one to use as you only need to degrease first. You dont need developer or anything fancy.
I can send you a can to try if you want?
I can send you a can to try if you want?
Mid Wales welder
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Hi Craig,
the cheapest option for you knowing your situation would be to use permanent magnets, but you can get a second hand electromagnetic yoke for maybe a few hundred pounds. A new yoke can be anywhere from about £700-£1500 depending on what you want.
As for brands it’s usually magnaflux or johnson & allen in industry, but I’m sure other brands are fine for light use as there isn’t really much to them to go wrong. have a look at the link for More info. https://www.ndt-consultants.co.uk/product-category/magnetic-particle/equipment/
the cheapest option for you knowing your situation would be to use permanent magnets, but you can get a second hand electromagnetic yoke for maybe a few hundred pounds. A new yoke can be anywhere from about £700-£1500 depending on what you want.
As for brands it’s usually magnaflux or johnson & allen in industry, but I’m sure other brands are fine for light use as there isn’t really much to them to go wrong. have a look at the link for More info. https://www.ndt-consultants.co.uk/product-category/magnetic-particle/equipment/
hotponyshoes
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My idea of partical testing is (and I only do it for hobby reasons so others might want to correct me on this) just to be sure we are talking about the same thing:
You can only test magnetic material (so it wont work on alloy or plastics etc)
You need some way of maginitising the item you want to test. This can be as basic as a regular magnet although you need to have enough magnetic power to cover the whole area you want to test.
You dont need to massively magnitise it, I use a bit of high carbon steel (old horseshoe rasp) and if it feels like it is attracting (tacky almost) that's good enough for me.
You can move a magnet around a bigger item and test in patches or stack several magnets to increase the force.
Next is the test fluid. There are various types of this. Some need 3 or more parts, a primer the fluid and the developer but there are various systems doing it different ways. The fluid consists of tiny (really tiny) magnetic particles. The particles are reactive to UV light (ie they glow brightly under uv light) This is about the only was to see them with the naked eye as they are too small otherwise.
They are suspended in a special fluid that keeps them suspended and allows them to move freely around.
The basic idea is, remember messing about with magnets and iron fillings at school, the iron fillings would form pretty patterns around the poles of the magnet and make the magnetic fields visible.
When you magnitise a piece you want to test any cracks or imperfections will disrupt the magnetic field and create smaller magnetic fields of there own.
The stuff I use is 14hf, all you need to do is make sure the part is degreased completely. You then spray the fluid over the part. The tiny particles will be evenly distributed over the surface but if there are any imperfections in the part the particles will be attracted to them and line up with the smaller magnetic fields (much like the iron filings would)
You then shine a uv light over everything and any small flaws or cracks are easy to spot as you get a glowing cluster of the little particles.
For anything other than hobby testing for parts that are for you own use (engine rebuild or something) things get a bit more advanced.
For detecting sub surface flaws I think you need to pass a current through the part as sticking magnets to it mostly creates fields around the skin layer of the surface. I have heard of people doing this using both ac and dc tig welders as the power source. Proper rigs can also use several sets of coils so it's easy to switch the direction of the field. For proper testing you need to test at more than one magnetic orientation to ensure you dont just happen to line up a flaw with the field and not see anything.
I have seen decent engine builders using magnetic grinder chucks and testing crankshafts by turning them around.
I suppose it depends on how critical the application is as to how seriously you need to test it.
The stuff I have is aerosol cans of the test fluid. I use a car air-con leak test uv torch and the special goggles (you dont need the goggles really, certainly not if you turn the lights out).
I can pop a can in the post for you to have a play with, pm me the address.
The other thing I use it for is it's very good for finding tiny leaks as the suspension fluid is highly penetrative. If you pull the cam out of a cylinder head and pop it on a couple of blocks you can spray it down the inlet & exhaust ports. Wait 5 and shine the light underneath and if any of the valves are not seated properly it's obvious by the glowing green ring.
You can only test magnetic material (so it wont work on alloy or plastics etc)
You need some way of maginitising the item you want to test. This can be as basic as a regular magnet although you need to have enough magnetic power to cover the whole area you want to test.
You dont need to massively magnitise it, I use a bit of high carbon steel (old horseshoe rasp) and if it feels like it is attracting (tacky almost) that's good enough for me.
You can move a magnet around a bigger item and test in patches or stack several magnets to increase the force.
Next is the test fluid. There are various types of this. Some need 3 or more parts, a primer the fluid and the developer but there are various systems doing it different ways. The fluid consists of tiny (really tiny) magnetic particles. The particles are reactive to UV light (ie they glow brightly under uv light) This is about the only was to see them with the naked eye as they are too small otherwise.
They are suspended in a special fluid that keeps them suspended and allows them to move freely around.
The basic idea is, remember messing about with magnets and iron fillings at school, the iron fillings would form pretty patterns around the poles of the magnet and make the magnetic fields visible.
When you magnitise a piece you want to test any cracks or imperfections will disrupt the magnetic field and create smaller magnetic fields of there own.
The stuff I use is 14hf, all you need to do is make sure the part is degreased completely. You then spray the fluid over the part. The tiny particles will be evenly distributed over the surface but if there are any imperfections in the part the particles will be attracted to them and line up with the smaller magnetic fields (much like the iron filings would)
You then shine a uv light over everything and any small flaws or cracks are easy to spot as you get a glowing cluster of the little particles.
For anything other than hobby testing for parts that are for you own use (engine rebuild or something) things get a bit more advanced.
For detecting sub surface flaws I think you need to pass a current through the part as sticking magnets to it mostly creates fields around the skin layer of the surface. I have heard of people doing this using both ac and dc tig welders as the power source. Proper rigs can also use several sets of coils so it's easy to switch the direction of the field. For proper testing you need to test at more than one magnetic orientation to ensure you dont just happen to line up a flaw with the field and not see anything.
I have seen decent engine builders using magnetic grinder chucks and testing crankshafts by turning them around.
I suppose it depends on how critical the application is as to how seriously you need to test it.
The stuff I have is aerosol cans of the test fluid. I use a car air-con leak test uv torch and the special goggles (you dont need the goggles really, certainly not if you turn the lights out).
I can pop a can in the post for you to have a play with, pm me the address.
The other thing I use it for is it's very good for finding tiny leaks as the suspension fluid is highly penetrative. If you pull the cam out of a cylinder head and pop it on a couple of blocks you can spray it down the inlet & exhaust ports. Wait 5 and shine the light underneath and if any of the valves are not seated properly it's obvious by the glowing green ring.
Mid Wales welder
Welder coding and NDT services
- Messages
- 672
- Location
- Powys, U.K.
This is a great explanation of the process in layman’s terms 
