Minizing Thickness Reduction During Hot Forming

please post more information, the more you give the more you recieve! How many pressings are being done for the output product, what material, what size, what tools are being used etc.?

I assume that you already know that when hot forming plate it tends to stretch and therefore reducing in section thickness is inevitable. By using a stepped pressing process, (i.e. form the outer edge and then a plate with an uptuned lip, then a bowl, then shape into hemisphere) you can direct where this reduction in section can occur.

I would look into automotive manufacturing for car panels, as these are often multi-stepped pressings, although i am unsure if they are done hot or cold.

Material : SA 516 gr 60/65/70

Press used :- 1000 tons hydraulic press .

Not a production job . As per cleints specification

Recently we hot formed a 1250 mm ID X 28 mmthk ,Radius = 625 mm hemi head

The After forming thickness acheived was 23 mm . (Single pressing )

Can you suggest any method to control the thinning process .

Nileshh

Sometimes it's to wet to plow...

Hello motilalgroup, As others have said more info would be useful please. If you are 'moulding' these items, can you not increase the mould head size by 15% so the finished part is the correct size? Just a thought. Take Care

You will have to either start with thicker material (Simplest method).

OR:

If you start with a larger diameter blank, then pre-form it (more oval than hemispheric) so the diameter will fit into your final form. Pressing this will hold and perhaps thicken the part.

I am assuming the final die is one which the part is totally contained. If not, this will not help as the material will squeeze out the opening.

Some where in the late 60's I saw a process called "Hydroforming " which could actually thicken a part during the forming process. Do a search for that term if you want more details on it.

Good Luck,