Brinell Drop Test

Discussion in 'Workshop Tips and Secrets / Tools' started by proppastie, Feb 28, 2018.

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  1. Feb 28, 2018 #1

    proppastie

    proppastie

    proppastie

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    Using "junk yard metal" I decided to check the hardness of some Aluminum Angle I found. There are so many calculators on the internet that I did not have to write and de-bug a spread sheet. I plan on checking this calculation with a real hardness tester too and will let you know if there are any problems. 92 BN is 6061-t6..... 60 BN is 6063-t52. I actually think it is 6063 which is what I used for my stress calculations. A normal 500 kg test is held for 30 sec. so I am not sure if this is entirely accurate, I plan to check it against know material too. I was just so excited I had to post.

    IMG_20180227_202952.jpg IMG_20180227_202947.jpg IMG_20180227_210609.jpg brin3.jpg brin4.jpg brin2.jpg brin1.jpg
     
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  2. Feb 28, 2018 #2

    proppastie

    proppastie

    proppastie

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    Revised indent dia. and the height, it only dropped aprox. 1 m which gives a 72 BN. The reason I think it is 6063 is it has square corners and I do not see that mtl. in 6061. In any case I am pretty sure it is not soft mtl. which is what I was afraid of.

    I should use a 10mm ball but I do not have one of those yet.

    I attached a washer with dental floss as a plumb bob to the bottom of the weight to line up for the drop.

    I used clay to hold the ball on the angle mounted loose in a drill press vice on the floor, I did not clamp it.

    I am thinking of making a test rig with rods into a base to keep the weight falling straight and where I want it to fall. But that might add friction and the plumb bob works.

    What is so exciting is for zero cost I potentially can duplicated the results of a several thousand dollar machine.

    Links:

    http://www.livephysics.com/tools/mechanics-tools/solve-problem-related-impact-force-falling-object/

    https://www.gordonengland.co.uk/hardness/brinell.htm

    http://www.kylesconverter.com/mass/newtons-to-kilograms

    http://www.handymath.com/cgi-bin/arc18.cgi?submit=Entry
     
    Last edited: Feb 28, 2018
  3. Feb 28, 2018 #3

    wsimpso1

    wsimpso1

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    While you are attempting to do Brinnell testing, this is instead a NEW HARDNESS SCALE. The differences may be be small, and they may not be.

    The dead load of a Brinnell Tester makes full load all of the way down through the plastic and elastic deformation, and then the elastic deformation comes back off when the dead load is removed. The permanent deformation and thus the contact surface area measured is a function of the yield strength of the deformed material under the ball. This deformation occurs at very low strain rate, and so is indicative of behavior under slow load onset. Also, the sample is well supported with full load developed through the depth of the sample.

    In a drop test, the amount of plastic + elastic deformation is determined by the kinetic energy in the weight - permanent deformation achieved is a function then of the energy available, not necessarily the strength of the deformed material. Much of the deformation occurs at significant strain rate, many materials are sensitive to strain rate, which can result in under- or over-estimation of strength, and may be more or less appropriate to the loading cases of structures you are making. This drop test temporarily stores considerable energy in elastic deformation and in weight rotation that is released as the load diminishes late in the strike of the weight.

    With good choices made on weight and height, and correlation between your process and known materials/tempers, you can certainly tell if you are close on strength. Perhaps that part is already established, which saves you some work, but not all. There will still be differences between your runs and the other experimenters that you should have to correct for. Can you tell if you have 6061 or 6063? Doubtful. You should be able to tell if you have T6 vs T3 within an alloy, but remember, hardness is only one parameter of a material. Alloy choice has other effects that you will not see in a hardness check...

    If I was dealing with a flight safety part and its strength does not have generous factor of safety, I would still stick with mill marked materials.

    Billski
     
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  4. Feb 28, 2018 #4

    TFF

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    Without calibration on known materials, you can't believe it. I have to send my torque wrenches to the metrology lab every year at work. In school I had test standards when we played with the the Brinell equipment. Every NDT class I ever had had known standards to test with. Your process might be fine. But not without buying a foot of each type and seeing what happens to the known.
     
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  5. Feb 28, 2018 #5

    pictsidhe

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    It shouldn't be too hard to do a more brinell test? Steel frame, bottle jack, bathroom scale via a lever if you can't kludge a pressure gauge into the jack?
     
  6. Feb 28, 2018 #6

    proppastie

    proppastie

    proppastie

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    I was working up a design for adapters for my scale (load cell) to put in a 20 ton hydraulic press, when I thought of this, and it took all of 1 hr to do the test and find the web sites and input the numbers. I probably have spent more time with the posting. So not not too hard but lots more time.

    I will be doing more tests on known material.
     
  7. Feb 28, 2018 #7

    proppastie

    proppastie

    proppastie

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    The 500 kg and 3000 kg Brinell tests certainly are different than this....I hope to see with further work if there is a reasonable correlation. It certainly is an easy cost free test to do.
     
  8. Feb 28, 2018 #8

    12notes

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    If you're doing a drop ball test, and the ball is steel, you can put the ball in a hollow plastic cylinder, and mount a solenoid with a magnet at a right angle to the side of the cylinder. The magnet holds the ball in place until you fire the solenoid, which pulls the magnet away from the cylinder. That's what we use for our drop ball tester at work that goes up to 194".
     

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