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Manual jack press versus air assisted hydraulic jack


#1

I have a press with a 20 manual hydraulic jack for pressing and
embossing etc. I am thinking of upgrading to an air assisted
hydraulic jack. When I emboss I crank the jack until I physically
cannot get to press anymore using a 3 foot long pipe. The question:
What will generate more pressure an air assisted jack or the way I am
doing it? Any ideas. Thanks, Vince LaRochell


#2

Air assist will certainly relieve your arm, but will be loud and has
its own failures, and the feel of air-to-hydraulic systems tends to
be “squishy” compared to pure hydraulics. You may want to look around
at other hand pumps. Enerpac has some very nice models but not cheap,
Harbor Freight has auto-body working kits listing for $130 and $200
that have a knock-off of the same 10-ton hand pump"I think you’ll get
better leverage and flow from one of these than your typical bottle
jack, but it is rated at 10 tons instead of 20… and you’d need to
port your existing jack or replace it with a ported one, however
there may be other processes you would use a more dynamic hydraulic
setup for too.

If you go air-over, make sure you can supply the CFM’s needed, for
the duty cycle you want"it might not be very much, you might do well
with a small compressor building up pressure in an air tank which
could provide most of the work you need. A big enough tank could
allow you to charge it up when you’re not around (personally quieter)
and still allow for many press operations.

If you’re a scrapper and DIY type, or know someone who is, you might
be able to adapt an electric-hydraulic log splitter or perhaps small
garden tractor type power supply to do your bidding better and
cheaper than air-over.

Just my 3 c,
Ben


#3

Vincent - you would probably like the pneumatic pump for your jack.
It gets you to the pressure you want much faster. I would however
question whether you would get much more pressure.

Something else to look at is how much your press flexes at high
pressure.

If it is one of the commercial ones, that’s probably not much of an
issue.

Homemade presses often flex and at higher pressures can warp. Then
some of the pressure that you think you have is not used on your
work, but rather wasted warping your press.

I’ve had an electric Bonny Doon press since 1998. It makes it easy
to get repeated precise pressure.

Judy Hoch G.G.


#4

If your press is rated 20 tons max, then increasing its working load
by any means is asking for trouble.

If you need more tonnage, find, buy, or adapt a bigger one for your
needs.

I wanted a 200 ton plus press and found such an tool at a materials
testing lab. They were upgrading one of theirs and I got mine for
350 gbp. It will go to 250 tons and is a die breaker. Not a funny
thing to have let go You get no warning till metal starts to fly.

4 by 4in dia colums, with a working hyd pressure max of 10,000 psi.

You treat this bit of kit with respect. This is the tool to watch
metal flow like putty.

Ted.


#5

Vincent,

That’s a very good question. You will not see much, if any, change
in force exerted upon your workpiece by using an air-hydraulic pump,
but it will make it easier and faster to cycle your press. Whether
you pump by hand, or with air or electric hydraulic pumps, they all
produce the same maximum fluid pressure, about 10,000 psi.

If you need more force applied to your workpiece you can do one of
two things, get a press frame and ram rated for higher force, or
confine your pressing to smaller areas.

The force applied to your workpiece is directly related to surface
area. Your press is capable of 20 tons per square inch. If your
workpiece is 4 square inches then you can only exert a maximum of 5
tons per square inch. The converse of this is that with the same 20
ton press you can also exert 80 tons of force upon a dime sized
workpiece. This amount of force is enough to be very dangerous
because a lot of materials break or shatter with less force than 80
tons per square inch.

If you are embossing, try using a smaller piece of urethane, cut a
1" square of 1/16" thick 95 durometer, and press your workpiece
multiple times moving the 1" square around the workpiece. By
observing the force needed per-square-inch to achieve the desired
results you can then calculate if you need a press with more
available force.

Air-hydraulic pumps are relatively inexpensive, but they are noisy
and require a lot of air pressure and volume. When you factor in an
air compressor the cost goes up considerably. Electric pumps are more
expensive but are quiet and easy to maintain. Either of these
options will give you faster cycle times but no more force is exerted
on your piece. The drawback with either of these two options is that
they are more difficult to control, things move faster, and you’ll
have less sensitivity to the pressing of your work.

I hope this helps,
Phil

or an electric pump, or a manual pump.

The force available is whatever your ram is rated at, how you move
the hydraulic fluid is


#6
When I emboss I crank the jack until I physically cannot get to
press anymore using a 3 foot long pipe. 

Whoa, what PSI are you going up to? I’ve never had to jack my press
up further than is advised for safety reason, and I still get a good
embossing.

Elaine


#7
When I emboss I crank the jack until I physically cannot get to
press anymore using a 3 foot long pipe. Whoa, what PSI are you
going up to? I've never had to jack my press up further than is
advised for safety reason, and I still get a good embossing. 

Here are some “Rules of Thumb” regarding the pressure needed to
emboss in a hydraulic press:: The finer the detail, the higher
pressure that is needed.

The thicker the metal, the more pressure that is needed.

The larger the area, the more pressure that is needed.

For crisp detail, use hard urethane (red 95)

For crisp detail, use the thinnest urethane that can be used without
damaging the urethane (2-3 times thicker than then area being
pressed)

For crisp detail, it may be necessary to press small areas at a time
(the smaller the area being pressed, the greater the pressure per
inch)

Cynthia Eid
Cynthiaeid.com