Choosing test samples for X-Ray

Hello everyone,

I have a X-Ray inspector installed on the line (chips in cans) and I'm going to challenge it:

- try test samples of different materials and different size to check their detectability and find the smallest detectable ones;

- find the weakest (less detectable) position in the can - both on horizontal and vertical axes;

The question is whether I need to search for the weakest position with all the test materials or it's enough to take any single material for this testing? Is there any correlation between an object material and its weakest position inside the can?

I have single horizontal beam X-Ray.

 

Regards,

Constantine

Yes, there is a correlation based on the design of your can -vs- the material used. In my experience the weakest point is generally due to the construction not the material. That being said, if you have some material that is inferior due to poor manufacturing from your supplier-that could effect your outcome.

Hi Constantine,

 

this is a setup principle used e.g. with MD. I am not sure whether this is the worst case for x-ray. In x-ray the density is of importance. The worst case would by in my opinion increasing density in the same level the beam has to pass. We have some problems when crystallization occurs e.g with sugar containing slurries placed together with fruits or nuts on a product. In that case we have false-positive withdrawals. Then you are going to reduce senisitivity and ....

If you can exclude such effects I don't see that changing of the position makes a difference. Is the scheme correct if you are using a moving belt? Then you will not have such angle but a straight beam through the pack.

 

Rgds

moskito

Hi Constantine,

 

You may try testing test pieces in various positions in cans such as - on top of product, in can body region, touching side walls - especially leading & trailing edges, on can bottom, in the corner on can bottom, in the grooves if can bottom is not flat etc.  Can side walls & top may show different performance than can body and can bottom would be worse.  Performance would be different for different test piece materials but difficulty in detecting in different positions would be relatively similar i.e. can body would be easier for same contaminant type compared to side walls and can bottom.

The only thing to mention is that an x ray "sees" things in 2D whereas a MD does so in 3D so as you've done you've identified the direction of beam.  This might then mean the across pack differences are smaller, however here is a big but

 

BUT :roflmao:

 

don't forget you're not just testing detection but also rejection.  The pieces being in the front and back of packs are often to test the rejection mechanism is timed correctly rather than they can be detected.

Just wanted to add that, due to metal edges of cans, contaminants touching leading & trailing edges are difficult to detect compared to same contaminant in can body region. Hence it is not just for reject timing. Normally reject timing should not be affected for x-ray depending on contaminant location (leading/ trailing edge) as whole product image is analyzed and reject signal generated, unlike metal detectors.