Francois

Forge Welding Press Tonnage

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Hi. I am building a forge welding press to make damascus billets for knife making. I have most of the parts I need and I got them from classifieds so they are second hand. The cylinder I have is not the biggest thing int he world with a 15cm stroke and a 50mm bore. I wanted to make it press around 15 ton at 3cm per second, but this simply is not possible with the motor I have (single phase, I would need around 700 bar and the pump I would need for that will basically kill the motor). I have estimated that I could get a max of 4.5 ton at the 3cm per second speed and that is pushing the limits. Would 4.5 ton be enough or am I seriously wasting my time?  Will it draw the steel out too slowly after welding basically...

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Current thinking is that speed is as if not more important than tonnage.  In a forging press a fast (more than 2.5" or 65mm per sec.) running at 15 tons will do more work than a slow 50 ton press.   That being said 4.5t is pretty small, more in the range of a hand powered fly press.  Use very small surface area dies, and even then your gear is probably too small.  

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Hey Judson and Thomas. Thanks for the info!

@Judson yeah 4.5t is pretty meager. I will have to get a cylinder that is at least twice the size (100mm bore). I worked out I can get around 15t at 3cm per second at 200 bar if I do that. It just means I have to modify the H-frame I already built. But thank you for the valuable information. I was thinking of using small surface area drawing dies, but I think it just won't be enough in the end and that is why I started this topic.

@Thomas the billets are on average roughly 10cm x 5cm x 5cm (kinda enough to make a big Bowie knife with some spare material). I have built a leafspring (Appalachian) type power hammer that I usually use for drawing out after welding by hand, but I feel it is just not moving the steel fast enough and I was drooling over some forging press videos on youtube.  But yeah, maybe I can simply use the press for getting better welds and see how I can up the ram weight on the power hammer or improve my drawing dies until I find the hydraulic parts I need.

Will see what I can find in terms of 100mm bore cylinders on my local classifieds today.

Thanks again for the info and have a nice day :)

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If you are going to use the same motor with a bigger dia ram and expect the same tonnage the speed will be the same as you will be pumping more oil at a lower pressure, if you stick with the bigger ram and same motor and use a smaller pump to pump less oil at a higher pressure equals more tonnage and less speed its mechanical advantage like gearing in your car. Sorry only way for speed and tonnage is HP Cheers Beaver

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For welding?  Actually, pretty much zero, at least in theory.  Your not squashing the metal together to make it weld, your getting everything in contact so that it can weld.  In reality, however, even if you run the pieces through a surface grinder you've got irregularities and imperfections, not to mention flux or crud that needs to be squeezed out, so you need to squish everything together.  Check out vacuum welding for more info, it's the oxides that keep a hammer set down on a steel table from welding at room temp, if it was perfectly clean in a vacuum it'd be tack welded just from contact, this is a real issue NASA has.  One of the ways I was taught to forge weld, and I teach other's to forge weld, is to make "frontier damascus", just start with a large piece of steel, put a slightly smaller piece on it and bring up to heat and weld with the hammer.  It shows that it doesn't take much force, as all your really doing is getting the metal into solid contact with each other.  Heavy hammer blow, or a 50 ton press will not weld any better if it's not at temp and clean, than just heavy enough blows to squish crud out and bring the metal into contact.  If your pieces are clean and fairly flat, it really doesn't take much force at all to weld up solid.

4.5 ton will do it, (I've seen people weld small billets in a bench vise) but I'd likely do two welding heats or more.  You'll have to learn your machine.  When I built my press I've got it set for 20 ton, though I could crank it up to 25.  I primarily weld with it and do some forming, but mainly welding and doing mosaic damascus.  I really recommend 20 tons or more, with a two stage pump, not for welding, but for welding larger billets and other operations, and with a press it's always a balance between speed and pressure, read up here and else where, James Batson's "Build your own hydraulic forging press" has a lot of good info, and there are a lot of work in progress presses out there.  Build heavier than you think it will need and it might be strong enough.

 

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If you are really interested in the *process* then may I commend to your attention Tylecote's "Solid Phase Welding".

A solid phase weld is based on Temperature, Pressure and Cleanliness; max out any of those and you can probably get a weld: vacuum welding, explosive welding, forge welding, even galling a bolt!

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Abebooks.com lists one for only US$150 + 4 bucks shipping

Or you could go to your local public library and ILL one for less than the shipping cost....I always ILL expensive books first so I can decide if I have to own a copy myself...(my library charges a dollar per item and I get to keep it for 3 weeks)

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