I just found a Hydraulic power pack at the scrap yard with a 5hp 1700 single phase motor on it. No idea on the pump, that might get replaced anyways. 

Is 1700 rpm adequate for a forging press? Goal is to have something at least in the 2 inch per second range. Not to picky on the tonnage as long as it moves some metal. 

Good Morning,

YOU have to do the MATH to figure out what will work. Hydraulics is Mathmatics.

Neil

Yes, no, maybe so......we just don't know. The RPM is just one factor depending on what the pump puts out in gallons per minute and at what pressures combined with the proper cylinder internal volumes. It is a system, so the complete system needs to be sized to do what you want.

So..... what are the ratings for the potentially defunct system that you acquired? This is your baseline..... 

Robert Taylor

What's the area of the piston face, distance of stroke, how many gpm will the pump move, and time of stroke?  See if you can download Industrial Hydraulics written by Richard W. Vockroth it has all the formulas to figure out what you need to know.

Pnut

Look over the pump carefully and see if there are any serial numbers you can google. If you can identify the make and model, you should be able to find out the pump’s gpm (or at very least its displacement, which you can use to calculate its gpm).

Even if you don’t end up using it in a press, a 5hp single phase motor is a great find with lots of potential uses. 

Volume of fluid moved can be calculated by multiplying area of piston face x stroke length. Then volume divided by time of stroke= cubic inches of fluid per second. To figure gpm multiply cubic inches per second by 60 then divide by 231=gpm.  Simple huh

Pnut

Math isn't my strong suit since the TBI. Before that really but especially since then. I hope I got this correct. If not please correct it as needed. Thank you.

I guess what I'm asking is, is 1700 rmp good for a press? I'll work out the component particulars when I get to this project in the future. (I pulled the motor off the tank and there is a Marzocchi 5.47 gpm gear pump on it, says fixed displacement is that a single stage pump? ) 

Or do most people use a higher rpm motor in their builds? 

I'll definitely find a use for the motor, this was one of those you can't pass by opportunities for 25 cents a pound 

5.47 GPM sounds like it would definitely be enough, but I'm not very familiar with forging presses. Frosty is pretty knowledgeable about Hydraulics and JHCC recently built a forging press. They might be your best bet on finding out what you want to know. Maybe a PM to one or both of them might bear fruit.

Pnut

Good Morning,

5.47 GPM is the volume that the pump will put out at ????rpm (1700rpm?). Pressure is controlled by your Hose rating and your Pressure Relief Valve adjustment. Speed of the Ram is controlled by the diameter of your cylinder(s). Effort of your Press = the PSI of your system x the surface area of your piston(s). For faster motion = smaller piston. For more tonnage = larger piston. If you use a two stage pump, you get low pressure/high volume to take up the slack, quickly and high pressure/low volume to increase your Effort, slowly. It is all Simple Mathmatics, no complex calculations.

Neil

Ok, have any of you guys built a press out of a 1700 rpm motor? 

Good Morning,

Not trying to be a dingbat, but, the Motor and the Pump are just one piece of the puzzle. You have to do the Math to figure out what other components you will have to purchase to make it work. There are Hydraulic System books that will explain what to do and how to get there. There is not one answer. You have to figure out what you want it to work and how fast. There are many configurations. What is it you are trying to Press, walnuts, caterpillars or hot Iron. The dies of a Press suck the heat out of your work piece, if you are too slow. There is no way to make a Press do things like a Power hammer. A Power Hammer is in contact with the work piece only a fraction of a second. A Power Hammer works the surface of your work piece, a Hydraulic Press moves the work piece from the center, out (like when you squeeze a sausage with your hand).

Neil

Thank you but not asking about the Hydraulic system, I'm just asking if a 1700 rmp motor is adequate for a generic forging press, I really don't care what the end result tonnage is, just one that's worth the time it takes me to build  frame for it. Just as simple as that, am I wasting time with a 1700 rpm motor? That's what I'm asking. Most commercial ones I've seen are a higher rpm motor. Again I am well aware of the hydrolic system components that go into the equation. 

If your pump does indeed move 5.47 gpm at 1700 rpm, then hooking that up to a cylinder with a 5" diameter piston will give you just over 15 tons of pressure and about 1" per second of ram travel, all other things being equal. That's not bad, if a hair slow.

Please note that this is ENTIRELY dependent on the pump: if it's designed to move 5.47 gmp at 1700 rpm, great. However, if it's designed to move that volume at 3450 rpm, then you'll only be moving 2.73 gpm, which will double the tonnage but drop the speed down to about 1/2" per second, which is probably too slow. However, if you then go to a cylinder with a 4" piston, that will give you about 20 tons with about 2/3" per second, which is better.

This is all a long way of saying that a 5 hp motor running 1700 rpm CAN be used in a hydraulic press, BUT you absolutely MUST be sure that your pump and cylinder are properly sized to go with it. See if you can look up the specific model of your pump and find its technical data. If  your can find the gpm at a specific RPM, so much the better. You can also calculate gpm by multiplying the displacement of the pump (in cubic inches) by the speed of the motor (in rpm) and dividing by 231 (which is the number of cubic inches in a gallon).

 

Thanks! That's good news, Ill just keep the current pump on the unit then as it's rated at 5.47 at 1800 rpm. That would be 5.24 gpm using your equation. 

Good Morning Setlab,

We are trying to ask you to figure out your own system and configuration. To answer your original question, Yes it will work.

You aren't understanding the Math, you just changed from 1700 rpm to1800 rpm.  Increasing the rpm will increase your volume. If in fact your pump is rated for 5.47gpm at 1800 rpm, then all your calculations should be with that figure.

By increasing the cylinder diameter, you will INCREASE your tonnage. Volume of a round surface is, pi x radius/squared. If your pressure from the pump and relief valve system is one pressure, that is PSI, pounds per square inch. If you increase your cylinder size, you are increasing the 'per square inch' size. Going to a larger cylinder means the ram speed will go down, but the tonnage will go up.

You have to figure out your own system and make it work with your starting point, 5.47gpm @ 1800rpm.

Neil

Simple question was simple, reading is key. This topic became more frustrating than herding cats....... Smh

 

Thank you again JHCC

In your mind it was a simple question.  However the answer isn't as simple as you want it to be.  For a direct drive from the motor to a pump 1700 rpm may or may not be enough for a specific pump. Can it be made to work regardless?  Sure.  You can reduce or increase the rpm however you want using different sized pulleys or sprockets.  If the pump is designed to be used with a 3600 rpm motor, then you will only get about half the desired output with an 1800 rpm motor.  With 5 hp at your disposal you could probably step up the rpm to a pump rated for a 3600 rpm motor as long as it didn't require more than 2.5 hp.  Just like the trade off between speed and power of the press, you potentially have that same situation with the motor.

If you purchased them as a unit then most likely the motor matches the requirements of the pump, but it's not guaranteed.

The rpm of the motor is mostly irrelevant.  What matters is the volume and pressure the pump puts out with whatever rpm it is designed to use.  In theory at least you could have a pump designed to run at 10 rpm which could exceed your needs for pressure and volume output.  It would be a beast of a pump and would most likely not be practical, but it could be done.

This is what I was able to do with an equivalent 5 hp motor 

That is a 1” grade8 bolt 

On 10/8/2019 at 3:58 PM, Buzzkill said:

''The rpm of the motor is mostly irrelevant''

Hey, thanks buzzkill, glad someone here read my question for what it was and didn't add to it with lots of what if scenarios. Clear and concise, just like my question 

Informative read though, thank you.