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How much force is necessary to cut through mild steel plate?

How much force is necessary to cut through mild steel plate (1 cm maximum) and/or 15 cm angle iron?

I have a situation where I may need to remove roughly 50000 to 100000 kg of steel from a location and sell it as scrap. Much of it is in the form of large tanks and must be in much smaller pieces to sell to the scrap yard. The main problem... how do I chop these tanks into acceptable sized pieces in an economical way?

Using a saw or acetylene torch is too expensive. I do have a crane and quite a bit of steel around. My thought was to build a sheer of sorts (0.5m long x 2 m tall x 2.5cm thick) with available material that I can lift and drop using the crane. Dropping the sheer from about 10 m will get it to around 14 m/s at impact. With enough mass and small impact area, this should work.

The main question is how much force is necessary to cut through mild steel plate (1 cm maximum) and/or 15 cm angle iron? I can vary the dimensions and mass (about 4500 kg maximum) of the sheer.

If you have any other ideas, they are welcome.

Thanks,

Nab

Reply to
Nab
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my physics text says you will need about 10^7 newtons to shear a sheet of steel 1cm thick and 1 meter long. using impulses, this means your proposed guillotine should be in the right ballpark. don't know if this applies to round tanks though. anton

Reply to
anton jopko

I once read that the US Air Force used a shear dropped from a crane for cutting up unwanted aircraft. I think the article also mentioned that the weight of the shear in this case was two tons, and as these were fairly small aircraft it was probably being dropped from a similar height to yours. Now aircraft metal will be thinner and easier to cut than 1 cm steel plate, so I suspect you may have an uphill struggle here. You can get specially designed hydraulic shears for this kind of work (they are carried by an excavator), but I'm sure they'll cost a great deal more than oxyacetylene cutting.

Nevertheless, if you've got the time and the equipment you can always give it a try. You could try making a blade with a diagonal cutting edge or a point in the middle to help it to penetrate the tanks, but this might also cause the blade to bounce around dangerously. Also remember that if your blade is made from the same material as you're cutting you'll need to sharpen it pretty often, which will be hard work. Take care as this has the potential for a number of undesirable outcomes!

Best wishes,

Chris

Reply to
Christopher Tidy

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