# Calculate dimension change with rolling mill and draw plate

Art there tables or methods to approximate the changes in length/width using a rolling mill and draw plate?

Calculating the change in length when using a draw-plate is simple - just multiply the old length by the change in cross-section area. For round wire, the change in area is proportional to the square of the diameters. For example: suppose you draw a 1.2mm diam wire down to 0.8mm diam. The new length will be (1.2/0.8) ^2 times the old length.
(1.2/0.8)^2 = 1.5^2 = 1.5x1.5 = 2.25, so the new length will be 2.25 times the old length.
The same calculation works when rolling square wire in the rolling mill.

Its much more complicated when want to roll round or square wire into a strip of a particular width and thickness. Suppose you want a strip 2.7mm wide, 0.8mm thick, and 60mm long.
The calculator I created at https://www.distorted.org.uk/dep-ui/rolling.html
will do this for you.
Enter 2.7 as the required width, 0.8 as its thickness, and 60 as its length. It will calculate that you should start with 40mm of 1.8mm square wire or 2.031mm round wire. You probably donâ€™t have that size in stock, so you just specify the size of the stock you have. If you have 4mm square stock you will need 8.1mm. Roll this down to 1.8mm square and you end up with 40mm. Anneal it, roll it down to 0.8mm thick, and you end up with a strip 2.7mm wide and 60mm long.

2 Likes

Gary,
Wow! Thank you. This very helpful. Your calculator is easy to use.

Frank Ruggiero, Ph.D.
Research Psychologist
Socio-Technical Solutions

Go to the hardware store and buy a bunch of copper wire in different gauges. Thatâ€™s not very precise, but that is what I do. Compare the before and after lengths, weights or whatever makes sense and then use a proportion to figure out, if I start with this, I get that when I am done. Now here is the hard part, write it down in a notebook that you might not lose so that you can refer to it later. Adjust the proportion based on future experience. I have done this for years and it doesnâ€™t fail me. Sorry, but we sometimes just make this all too difficult and it supposed to be funâ€¦Rob

Robert,
Thank you. I understand about â€śwriting it downâ€ť and remembering where I put notebook. Great suggestion.

Frank Ruggiero, Ph.D.
Research Psychologist
Socio-Technical Solutions

I forgot to mention that, because the calculator is actually calculating changes in area of cross section, it can also calculate the change in length when you simply change the linear size of a dimension without changing its shape. It works for any shape: round, square, oval, star, etc.
Suppose, for instance, you have some oval wire 3x2mm and you want to draw it down to oval wire 1.4x0.93mm, 60mm long. Notice that the shape is not changing: the ratio 3/2 is the same as the ratio 1.4/0.93.
You tell the calculator that you want square strip 1.4mm wide, 1.4mm thick and 60mm long. Tell it that you have 3mm square stock and it tells you that you will need 13.067mm of it. You just ignore the â€śYou should start withâ€ť section.
If you draw (or roll) the 13.067mm oval wire down to 1.4x0.93 you end up with 60mm of it.
No need to experiment and record with various lengths of copper wire - the calculator is there when you need it.

Gary
Thanks for sharing this very useful tool.
Do you by chance have any other calculation tools available?
Regards
Milt

I see my brother gave the same reply I was fixing to send. Our Dad never had a working rolling Mill in my memory but he, meaning Rob and I, Drew a lot of wire. He took lots of notes, usually on the side of the cabinet or on the frame of the florescent lamp above the bench.

Like Rob I refer to note books. By the time I do the math I could have drawn down a concert of wire.

Don Meixner.

Sent from my Verizon Wireless 4G LTE DROIDOn May 17, 2017 7:56 PM, Frank Ruggiero <orchid@ganoksin.com> wrote:

FTRsolutions

May 17

Gary,

Wow! Thank you. This very helpful. Your calculator is easy to use.

Frank Ruggiero, Ph.D.

Research Psychologist

Socio-Technical Solutions

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Frank- "and remembering where I put notebook"
Ha ha ha ha ha!

When you find that note book would you please tell me where my keys are
and why I walked into this room?
I can recognize across a crowded room a piece of jewelry I worked on or
made decades ago but canâ€™t remember the name of the person I just met ten
minutes ago.
-Jo Haemer

Re memory: so true! Iâ€™ve often wondered why we know where to go, but not why we went there once we get there. Since this also happens to relatively young people, my theory is that where we are must matter more to survival than what we possess or what we do. (-; Location, location, location!

<< When you find that note book would you please tell me where my keys are and why I walked into this room? >>

• ``     Lorraine``