Britguy Posted June 26, 2021 Share Posted June 26, 2021 I'm just designing my hydraulics and wanted to know what you guys think the ideal press/ram speed is for a press. I have a 6" diameter ram, and as yet no motor or pump, so skys the limit. Thanks. Quote Link to comment Share on other sites More sharing options...
Ted Ewert Posted June 26, 2021 Share Posted June 26, 2021 I'm in the research phase myself, and from what I understand, speed would be conditional on the capacity of the hydraulic motor to pump fluid. I guess you want it fast enough so you're not waiting around for the ram to descend while the work is cooling off. A press is not like a power hammer where speed is a significant factor in the forming process. Quote Link to comment Share on other sites More sharing options...
bubba682 Posted June 26, 2021 Share Posted June 26, 2021 Speed is important in a press and so is warming the dies up to help prevent heat loss in the piece your working on.I'd rather a small 15/20 ton two stage press with 3 to 4 ''a second travel over a slow heavier press any day.Now if your running a pro shop with a big budget, the sky is the limit that might be differant but for me makin damascus billits and blacksmithing for a hobby is what i'm basing that comment on. Quote Link to comment Share on other sites More sharing options...
Britguy Posted June 27, 2021 Author Share Posted June 27, 2021 Okay, wow 4" a second is pretty darn fast. I dont know if i'd have the skill to stop it in time unless i had stops/height blocks etc. But thanks for the advice. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 28, 2021 Share Posted June 28, 2021 3"-4"/second isn't a recommended speed. He is stating a personal preference. I'll add to that small dies are also force multipliers and reduce the amount of heat lost to contact. You calculate a hydraulic ram's force by lbs x sq" of piston surface. You have a 6" dia piston for 28.27 sq/in of surface. Supply 1,000lbs. of pressure and it will apply 14+ tons of force. Yes? Ram speed is a function of gallons per minute of fluid divided by sq in of piston surface. That's gpm/sq" Piston. A US gallon is 231 cu/in. So 1 US gallon of hydraulic fluid will move your piston 8.17". If you guys use imperial gallons you get to do the math, I'm mathed out. To move YOUR piston 4"/min you'd have to have a pump that delivered 30gpm. you'd have to look up the horse power requirement for that. To provide a meaningful force, say 30-40 tons it'd require between 2,142lbs and 2,860 lbs. of pressure. So not as much HP requirement as the gpm makes it sound. So, if you bought a pump that put out 15GPM. the piston would move 2"/second. and if the pump developed say 3,500psi. it'd apply 49.47 tons of force. Does that make sense? It's really pretty straight forward but I can confuse the simplest stuff. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Britguy Posted June 28, 2021 Author Share Posted June 28, 2021 Hi Frosty, thanks for the great reply. I can however, work out the speed/HP etc (I have the formula's all down, inc losses etc). My dilemma however, is trying to decide on a decently fast, but controllable ram speed when it contacts the work. Our pumps here (NZ) are usually given in Lts/rev just to make it more confusing! Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 28, 2021 Share Posted June 28, 2021 You're welcome, I spent too many years keeping the hydraulics on our drill rigs working not to have some use for it now. I'll leave the conversions to metric and how you folk down under work ratios to you. The ram will slow down when it runs into resistance so 2"/second free will slow quickly when it runs into hot steel it may drop to fractions of an inch per second. If you need it to slow down more you can put a "bypass over pressure" circuit in the hydraulic line on the high pressure side. The intend of a bypass over pressure is to limit the total pressure to the system. If you don't want 50 tons you can buy a pressure relief valve that allows more than say, 2,500 lbs/sq/in to flow back into the reservoir. A good control valve will already have a bypass over pressure valve built into it and maybe it can be changed to suit or perhaps you can buy one preset for what you need. The problem we run into having this conversation is YOU don't know what you want, need or can handle so worrying about these details is like trying to decide what high performance parts to put in an engine before you know how to drive. Yes? You WILL have your hand or foot on the control valve any time a forging press is moving let go of the handle or lift it when it's gone as far as you want. it'll take some practice just use some largish random stock and play with it till you get the fell of it. Don't try to make Enkidu's hammer the first time you try it. Find a piece of scrap say an old axle, get it HOT and smoosh it in the forge press. You'll get the hang of it in minutes and be doing precise work with it in a couple hours max. Honest, these things are very intuitive to use it's like judging if a peach is ripe by how it feels, it takes a couple times and you've got it. Yes? Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
bubba682 Posted June 28, 2021 Share Posted June 28, 2021 The press is fast that i made but as soon as it comes in contact it slows down and the dies i use to make damascus are 2''x4'' but my quote was meant about getting the dies and material together quick as to not lose to much heat.Some presses you see take to long to start squeesing and guys are working the material to cold.And also my ram speed was not a personnel choice its just how it worked out with 2 stage pump i put on .I aint no hydraulics guy but i know a few and if i recall my relief pressure is 2500 lbs sq in and the pump is 16 gpm but i will say i like the speed and precision its a great tool. Quote Link to comment Share on other sites More sharing options...
swedefiddle Posted June 28, 2021 Share Posted June 28, 2021 Good Morning New Zealand, I would recommend a 2-stage pump. 1 stage is Low Pressure/High Volume, 2-stage is High Pressure/Low Volume. The first stage takes up all the play between your Dies and your work piece, quite quickly (not much heat loss). When the dies come under load, the pump switches to High Pressure/Low Volume and your working pressure goes up (everything will start creaking and groaning, this is NORMAL). You will have time to watch what is going on and make an adjustment. The School of Hard-Knocks is the best teacher. A 6" cylinder will be slower than a 4" cylinder. You have your hand on the Control lever, you are in control!! Neil Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 28, 2021 Share Posted June 28, 2021 What Frosty said; you don't go into detail on how you want to use the press: Repousse where a slower speed is ok; Drawing where faster is better. Punching/drifting where a moderate to high speed works; etc. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 28, 2021 Share Posted June 28, 2021 Sorry Bubba I mis-interpreted what you'd said even though you said it in plain English. My bad. I agree getting the dies into contact fast is better than more pressure. If the steel is hot enough less pressure WILL do more work. I didn't go into 2 stage pumps for a reason Neil. I didn't want to add another layer to a confusing enough subject for folk who haven't worked with hydraulics. You most certainly CAN get single stage pumps that provide high volume Or high pressure or almost any combination of the two. They're built all over the spectrum. I agree 2 stage would be my choice too, especially if I had such a nice large piston and I'll be happy talk about it later after, after Britguy has had some time to absorb what's been said so far and see what he has available. Make sense? Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Britguy Posted June 29, 2021 Author Share Posted June 29, 2021 Thanks everyone, some good advice. As for the use of the press, well a bit of everything (drawing I will use a rolling mill/hammer). Mainly for billet making, but I guess I will use it for all the usual things a bladesmith might want. Also other shop projects. I was told by a local hydraulic supply rep to consider doing a regeneration circuit instead of a 2 stage pump. But with this you do lose some power in the working stroke. I guess ideally I could go for a fast ram speed (I know they slow down on contact with resistance), and have a speed control maybe. Or, I'm just overthinking it all. Oh, just to mention, I have worked on hydraulics some years ago, and I have some understanding ie I can read a hydraulic schematic etc. I'm an electrical engineer with plumbing, fitting and other such skills... oh, have my own machine shop etc etc. Just been designing gas furness and kilns. Also built my hydraulic press from scratch (apart from hydraulics). Not bragging at all, just trying to give some background. It was purely a "speed" question. I have used presses/hammers/rolling mills previously, but to be honest, never took a great deal of notice of speed, and also I know you guys are far more hands on experienced with such things. ;-) Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 8, 2021 Share Posted July 8, 2021 Your speed control is the valve handle, reducing the pump RPM reduces both power and speed. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
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