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Searing stainless steel

When sheet metal is cut in a shear, the sheet is bent up and down on either side of the cut.

Guillotines and shears are rated on the thickness of mild steel sheet they will cut, and for stainless steel in a guillotine you de-rate by a half, the approximate ratio of the material shear strengths.

With a shear, the plate bending could be what limits the performance. As the force required to bend the sheet ( without permanent deformation ) depends on young's modulus, which is essentially the same for both mild and stainless steel, no de rating would be necessary.

Has anybody got information on the sheet capacity on mild steel for a shear suitable for cutting 3mm thick 304 grade stainless steel sheets ?

-- Jonathan

Barnes's theorem; for every foolproof device there is a fool greater than the proof.

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Reply to
Jonathan Barnes
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Jonathon,

I have a few comments which I hope will be worthwhile.

1 You might consider it wise to ask the manufacturers of the guillotine own or favour for purchase. 2 It often happens that, especially older type mechanical guillotines, can easily cope, cutting beyond well rated capacity & not infrequentlya small adjustment to the PR valve of a hydraulic machine will allow you to "just mak it". 3 It's wise to have a clear idea about eventual use. Higher speed production cutting reqires a more robust design than slower (often the case with hydraulic machines) cutting, used primarily on a jobbing basis. 4 T304 stainless now, tomorrow it might be T316, an entirely different animal. 5 Your broad rule of thumb is correct, 3/16" rated guillotine will be needed for T304 stainless.

Rgds. Peter

Reply to
Peter O

You already have part of your answer. A shear can handle mild stee

about twice as thick as stainless, BUT you will probably need to adjus the machine to the material being cut for best results.

If the edges of the sheet are bent over or have a significant burr o the edge then the knife clearance is too large or the knives are dull.

For really good results the knife rake may also be adjusted. Amad makes a few lines of shears that all of the adjustments can be mad from the control panel so the machine can very quickly change fro cutting thin decorative sheet to cutting light plate. Very expensive t purchase though

-- pipedop

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pipedope

Peter

I'm not considering a guillotine, as I only have to work sheet very occasionally, and can't justify the space or cost... A shear is just O.K. as it can be put it away in a corner when it's not in use.

I should have said that de rating is to the square of the ratios of shear stress, to give about 0.5 for mild / stainless steel.

When I have a batch of sheet work I have the use of a seriously big guillotine ( 2.5m X 12mm ), but it's a 20 mile trip... :-(.. I want the shear for prototype and one off jobs.

Reply to
Jonathan Barnes

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