Hello Everyone,
Has anyone experienced unsafe conditions when using a small 10,000 lb
hydraulic press? I am concerned because during my days as a student,
my instructors always caution us that something might project out of
the press at a high enough speed to hurt someone. Now I am in charge
of the maintenance and safety of a studio where beginning students
have access to such equipment. Is there reason for concern, in your
opinion?
LPV
Has anyone experienced unsafe conditions when using a small 10,000 lb hydraulic press?
Yes! I have been hit in the chest by a rather large piece (3 lbs) of
a hardened steel plate that was improperly supported and fractured. I
am assuming that you are referring to a 20 ton press that has 10,000
psi hydraulic pressure. You can so easily exceed the working limit of
tools that are not specifically designed for this kind of force. Most
often this just results in ruined tools and work but, when this
happens to hardened steel it can fracture and throw off pieces with a
significant velocity. Using tools designed for the press is the best
course of action. If you are not using tooling specifically designed
for the press you need to approach how you proceed with care and more
than a little common sense.
Jim
James Binnion
James Binnion Metal Arts
Hi Laura:
Iāve seen a plastic die āsquirtedā out of the side of a bonny-doon
press, but that particular press was being operated in very
improvised conditions, (at a camp), and the die was covered in lard.
(So was the press. They were doing a lot of deep drawing.) Thatās why
the Bonny- doons are rigged so that the upright barās between you and
the die when youāre pumping a manual press. The die came out of there
fast enough that it probably would have hurt (a lot) if itād hit
anyone, but it bounced off a pine wall about 15 feet away, and didnāt
leave much of a dent, so it wouldnāt have been lethal. In the post
āsquirtā examination, near as they could tell, there were two or
three major factors that led to the die being ejected. (A) the press
was set up at a slight angle, due to the table (and the floor) not
being flat. (B) the die, platens and flexane were coated in lard.
That probably had more to do with it than anything. (not
deliberately, but just from cross contamination from larded hands.)
and Ā© the die had been placed onto the platens off-center. Combine
off-center stress with well-lubed rubber, and you have a recipe for
flying dies.
If youāre trying to set up safety procedures, Iād talk to Cindy Eid
or Anne Larsen for the definitive word, but my take would be:
(A) everything must be centered over the ram,
(B) you must wear safety glasses.
Ā© you must stand on the side of the press (where the upright
will catch anything trying to fly out at you.)
I let beginners loose on ours (a Mk1 and a MkIII) every week, with
those rules in place, and a firm warning to make sure nobody else is
standing in the path of the open faces of the press when they use
it, and Iāve never had a problem.
Except for that one incident, Iāve never seen or heard of a die
squirting out of one of those presses in nearly 20 years of using
them. I do sometimes worry about dies fracturing and shards popping
out, but Iāve never seen one of those do anything more than just
snap.
FWIW
Brian Meek.
recommend using a plexiglass safety shield, you an make one, a
cylinder, that simply slips over the press.
bits of an object can fly out of brittle materials - a phenomena
called āexplosive decompressionā
warm regards
Hi Laura,
You might want be on the safe side by providing a clear shield around
the work piece, like a large clear PVC tube. Or you could make a
shield that goes in front of the press itself, like aplastic window.
Something could snap in the process and go flying. It would be best
to be certain that no one can be hurt.
Michelle
Hi Laura,
When I first started teaching about use of the hydraulic press, I
asked the folks at the Discussion Group at bonnydoonengineering.com
what should be included in a safety tip sheet for students.
Coincidentally, yesterday I updated that safety sheet, to put on the
wall next to the beautiful new press that Phil Poirier, current owner
of Bonny Doon Engineering, donated to Metalwerx. (THANK YOU, PHIL!)
Iāve posted a pdf on the Discussion Group that you can download, and
printed it below. Press safely!
Cynthia Eid
HYDRAULIC PRESS SAFETY-Some Rules for Keeping Your Body and Tools
Safe and Whole (c) 2009 Cynthia Eid. Copies may be made for personal
and instructional use, but not for profit without permission.
USE THE PRESS ONLY FOR PROCEDURES THAT YOU HAVE BEEN TAUGHT HOW TO
DO SAFELY Like a car, operators need to have training. It is safe
when used carefully, but accidents can happen if the press is not
used correctly.
STAND IN FRONT OF THE FRAME for protection. Take care if someone is
standing in front of the open faces of the press. WEAR SAFETY GLASSES
OR A FACE SHIELD. Things can break under the pressures used in the
hydraulic press. Plexiglas will withstand incredible pressure if it
is fully supported by the platens, but if it is hanging over the
edge, and the urethane pad starts to push on the area that is hanging
over, the tools can become shrapnel.
ALWAYS CENTER THE WORK. Not only will this create a more even
impression, but the platen will not tilt under the pressure. Remember
that the platen āfloatsā on the ram, which makes it self-leveling, to
some extent, but also means that a tool placed off center can squirt
out of the press like a bullet!
ALWAYS BOLT TOOLING IN PLACE, A tool can fly out of the press if it
is not attached. Tooling attachment holes are in the top platen of
the press for this reason. This is especially important for tools
that are taller than their width.
DO NOT OVEREXTEND THE RAM. THE STEEL RISER BLOCK AND SPACER BLOCKS
MUST BE USED, UNLESS THE TOOLS ARE TOO TALL.
ALWAYS PROTECT THE STEEL PLATENS WITH KEVLAR FACE PLATES. Do not
press directly against the steel faces of the press. If there is not
room for the spacer block and face plate, use a piece of brass or
nickel to protect the steel.
NEVER TRY TO EMBOSS OR USE BLANKING DIES WITHOUT THE TOP SPACER. One
of the functions of he top spacer is to cover the tooling holes.
These holes can damage your tools.
URETHANE SHOULD BE AT LEAST TWICE AS THICK AS THE DEPTH YOU ARE
PUSHING INTO. If the urethane is too thin, it shatters. Punches are
best used with a contained block of urethane. Ideally, push only to a
depth of 1/3 of the thickness of the urethane.
NEVER, EVER, USE CAST IRON IN A PRESS. Learn from this guyās
experience: āI still have a minute piece embedded in my hand. Seems
like I was in too much of a hurry to go get a piece of steel for a
spacer and grabbed a cheap drill vise that was handy. It exploded at
about 5,000 pounds! Shrapnel every where.ā
AVOID USING TOOLS IN THE PRESS THAT WERE NOT MADE FOR USE IN THE
PRESS It is not safe to use a metalsmithing stakeā that was
intended to be hammered onā in the press. The cast stakes are not
designed for use in this fashion; they may shatter. They can also be
difficult to fasten to the press.
AVOID USING HYDRAULIC PRESS TOOLS FOR OTHER USES IN THE STUDIO For
instance, a mushroom punch made for the press will stand up to tons
of pressure, but may break off its stem if hammered on in a vise.
DO NOT EXCEED THE PROPER PRESSURE FOR THE JOB. Always try the lowest
recommended pressure, and check the work. It is nearly always
possible to repeat at a higher pressure.
DO NOT OPERATE THE PRESS UNDER THE INFLUENCE OF ALCOHOL, DRUGS,
MEDICATIONS, or FATIGUE.
KEEP THE WORK AREA NEAT AND CLEAN. Cluttered work areas invite
injuries.
USE YOUR SENSES
WATCH what is happening inside the press! WATCH the gauge at the same
time. If the pressure suddenly increases, stop and check the
situation.
Remember to always watch and listen to what is happening between the
platens. The gauge is an additional guide, not the only thing to
watch when pumping.
FEEL āAs you pump, the pressure generally should gradually
increase. Stop if there is a sudden increase in difficulty. LISTEN
for
any noise that doesnāt āsound rightā. Stop and figure out the cause
of any odd noise. USE COMMON SENSE. If you think it might be a bad
idea, donāt do it!
ALWAYS LET THE RAM DOWN WHEN FINISHED FOR THE DAY. The ram is oily
and attracts dust and grit, which can then get inside the jack.
Moral of the story:
Cynthia, Thanks for posting the safety rules for the haudraulic
press. In order to assure that I have correctly centered my piece, I
use a ruler. I have an oblong shaped delrin block that I use as a
riser. I have marked off on my ruler the distances it needs to be
front to back, and side to side Using the ruler, I adjust the block
so that it is exactly in the center. If not centered the platen can
severely gouge the steel poles on which it rides up or down.
Another way is to paint with white paint, the area into which the
riser will go.
Alma Rands
I took a hydraulic press course with Cynthia Eid in 2005. During the
class we had bracelet components fly out twice. On following up with
Cynthia she felt there may have been a couple of factors. I still
have her email so will paste it here. Hope itās helpful. Nancy
Regarding making a plastic shield for a press: Polycarbonate plate is
one of the strongest and most shatterproof plastics available, much
more so than Plexiglass (acrylic). A trade name is Lexan, I believe.
To test it, I took a baseball bat to a piece of 3/8" plate and was
unable to break it. Would suggest at least 1/2" thick or more. The
banks use 1" thick to protect tellers from stray bullets, which are
very much like the shrapnel that can result from improper press use.
Phillip Baldwin, Shining Wave Metals
Greetings all:
Apropos of our discussions of flying tooling and fragmenting dies,
(and how rarely that happens), I had a thought.
Iāve only seen a die actually ejected from a press once, but Iāve
seen a number of plexiglass dies broken in various ways. Never in a
way that resulted in flying bits, but Iāve always worried about that.
It occurred to me that it might be useful to wrap the outer edges of
plexiglass dies in strapping tape. (the packing tape with the fibers
running along it.) It wonāt keep the die from breaking, but it just
might contain the fragments.
Anybody ever tried it? Thoughts?
Regards,
Brian.
Regarding making a plastic shield for a press: Polycarbonate plate is one of the strongest and most shatterproof plastics available, much more so than Plexiglass (acrylic). A trade name is Lexan, I believe. To test it, I took a baseball bat to a piece of 3/8" plate and was unable to break it. Would suggest at least 1/2" thick or more. The banks use 1" thick to protect tellers from stray bullets, which are very much like the shrapnel that can result from improper press use.
Iāll second the Lexan recommendation.
Just on a lark, I took a chunk of 1/2 lexan out to the range with me
once. It stopped a.40 cal pistol slug from about 10 yards. Made a
very pretty dent, but it held. At least against a wadcutter.
Hollowpoints chewed right through, and a.357 magnum shattered the
entire piece.
YMMV, but yeah, it will stop at least some bullets, some of the
time.
Regards,
Brian.