Hydraulic press, and "Ya got me under Pressure"

T Blade

T Blade

Joined
Aug 25, 2003
Messages
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I’ve been curious as to how much pressure you really need to get a high quality pattern weld.

I’ve hammer pattern welded several billets with good results in the past. About than 10 pieces I figure. When I was researching manual pattern welding, what I read about it more or less recommends using a lighter hammer i.e. instead of a #5 or #6 hammer use a #2.5 or #3 hammer. This recommendation I believe was more for preventing the individual sections of steel in the billet from sliding to the side thus preventing the weld from happening. The lighter hammer making a “straighter strike :jerkit: more easily controlled” if that’s the word I’m looking for, you know what I mean though.

Well anyway, I wonder how much psi you create at the impact point using a #3 hammer? More than or close too 30,000 psi, or are you only applying 10,000 to 15,000 psi? I really don’t know.

Page, you can't answer, I've seen you Hammer :eek:

If that is the case, than you certainly don’t need a 30,000psi press. I under stand that speed of your system is critical, “strike while the iron’s hot!”

As a matter of fact, my hydraulic system is underpowered so I had to turn the pressure relief from the factory setting of 3,000 to 25,00psi so as not to stall the alleged 110V 3HP motor that I have. When everything else is right, forge temp and atmosphere, nice "hot" dyes in my press, a good MoJo going, I can get a real good weld, (not that my MoJo is always is alway at its best ;)).

Now, if you want to talk about moving steel, well 40,000 or 60,000psi is the ticket. If you need to create enough steel in a day for 7 or 8 knives, yeah you need Pressure :D

Could any of you guys help me out, I'd really like to get your take on this subject.

Thanks

PS I love ZZ Top, especially the old stuff :thumbup::cool:
 
Hrmmm...I know that I use an 800g hammer to set welds of billets up to 3" or so thick with 13-15 layers, and I'm not wailing on it at all. I use a medium to medium-light blow to set the weld. I really don't think pressure is the key to welding. I know several guys who have had pieces weld together pretty well just sitting on the floor of the forge and touching.

The real way to measure this would be to get a load cell and strike it with similar blows to what you use in welding.

Anybody here work someplace they have access to load cells and the equipment to read them? This could be a neat experiment. :)

-d
 
I'm sorry, What is the exact question?
It takes very little pressure to make a weld. A hammer and an anvil will do it but to move steel it takes some real pressure. I run my pop-off valve at about 3000 psi but rarely let it get that high when pressing. Usually around 2500 psi. The die size seems to be the determining factor to manipulate hot metal. A small rounded top die will move metal much faster than a large one unless you have a huge press. My press has log splitter parts and isnt powerful but has enough power for making knives not mass production work.
 
If your steel is ground flat and held together from all sides the material will weld without any pressure at all. It is always good to provide enough pressure to just move the stack. For me that is less than 200psi. Most of my work is done below 500psi and in the first stage of the pump. The psi provided will depend on your cylinder size. At 2200 on the gauge my press has almost 50 tons of pressure. Once the billet is welded it is only a matter of moving the material at a pace you are comfortable with. I have seen 15 ton presses work just fine for smallish billets.
 
deker said:
... I know several guys who have had pieces weld together pretty well just sitting on the floor of the forge and touching....-d
Click to expand...

800 grs = 1.76 lbs.

I have had something like that happen. I was using vetical (Fogg style), and while I was taking the billet out, it touched against the side of the forge body, and I swear i felt a vibration through the piece up the welded stick and I knew that I just had a weld happen.


Bruce Bump said:
I'm sorry, What is the exact question?
.
Click to expand...

Sorry Bruce, I tend to babble a lot (Ask IG :D).
What I really wanted to understand is whether or not you actually need a 30 or 40,000 psi machine to get a successful weld.

A lot of guys who want to get a press will ask on the forum how big of a cylinder they need. It's alway nice to be able to get the most powerful machine that you can, but it would seem that it's not necessary.

As your heated stack of material does not stay at welding temperature for very long, I believe that a faster setup is much more important than a high pressure one.

Thanks for your thoughts guys. :thumbup:
 
The weld can be done in a vise. It is the working of a big billet that requires a large press. Drawing a 2X6X6 billet out by hand is an arduous task. With a 30 ton press, it is a joy. Same goes for canister billets. I think any press over 15 tons with a good ram speed will work.The billet size will be determined by the press capacity.
Stacy
 
Yup, what Stacy said. Except that I always overengineer things so my press will have a 6" cylinder. I don't HAVE to use all the power, but it'd be nice to have it for when I need it.

-d
 
bladsmth said:
The weld can be done in a vise. It is the working of a big billet that requires a large press. Drawing a 2X6X6 billet out by hand is an arduous task. With a 30 ton press, it is a joy. Same goes for canister billets. I think any press over 15 tons with a good ram speed will work.The billet size will be determined by the press capacity.
Stacy
Click to expand...


Wow, the fire box in my forge is 16" X4" X4". It's kind of small to do a billet that size. Stacey, do you mean 2" wide, 6" long and 6" high?. If I could heat a billet those dimensions, I'd be afraid that the stack would go sideways and I'd end up loosing the whole thing. The way my press is setup, it wouldn't apply the pressure centrally on a tall billet like that so it would most likely slide off to the side. I do have one set of dyes that is just a 4" square plate, I could probably get the stack a little closer to the center of the cylinder shaft to centralize the pressure. I feel comfortable welding a billet around 2" to 2 1/2" square, and the length doesn't matter, but usually the length is around 5" to 6".

-d, at this point in time, I'm not even getting the most out of my 5" bore cylinder. Yeah, when you can afford it bigger is usually better.
 
Yes, a lot of damascus makers make their billets out of 3/4" thick stock and the stack is 6" tall. I have done 4" stacks, but usually use 1/4" to 3/8" by 2" stock and stack to about 2" high. Those big billets require a dedicated large damascus forge.

The first pressing is to set the weld, and doesn't require much pressure. Most guys set the weld by hand first and then re-weld with the press. The reduction is in small bites, and won't squish the billet over unless you bite of more than the press can chew.

Stacy
 
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