I have been asked to sample a small prototype mold for a customer. I beleive the mold is too small for any of the injection presses I have available, and would like to know how one goes about determining what the maximum tonnage a die can take. To be clear I am not talking about the tonnage required to effectivly keep the mold clamped duing injection, but rather the force to crush the tool. I know there are a lot of variables: steel type, die design, etc, I am more so wondering if there is a general rule of thumb, say something like so many tons per square inch of landing area etc.
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Maximum tonnage a die can ahndle
- Thread starter xqv
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Can not you adjust the clamping force? I can only just remember machines with a fixed clamp force. ![[sad]](/data/assets/smilies/sad.gif "[sad] [sad]")
If you have big machines with large location diameters, you may bend the backing plates if you have to use adjusting rings, as the tool will not be adequately supported.
As a guide, 2 tons per square inch of projected part area will enable the moulding of just about anything (Including PC) - unless you are into high speed packaging moulding.
H
www.tynevalleyplastics.co.uk
It's ok to soar like an eagle, but weasels don't get sucked into jet engines.
If you have big machines with large location diameters, you may bend the backing plates if you have to use adjusting rings, as the tool will not be adequately supported.
As a guide, 2 tons per square inch of projected part area will enable the moulding of just about anything (Including PC) - unless you are into high speed packaging moulding.
H
www.tynevalleyplastics.co.uk
It's ok to soar like an eagle, but weasels don't get sucked into jet engines.
patprimmer
New member
Harry
I have seen a broken platen where a long narrow mould was bolted in between the supports instead of across them. It was a 1200 tonne press so the owner was not at all pleased.
My rule of thumb was always 3 tonne per sq inch of projected area.
Always set the clamp to no more than necessary to prevent the mould blowing open during injection. This is not so much to prevent the mould being crushed as it is to save wear on the toggle pins, the pumps and to save power.
I have also seen a mould you could easily run in a 40 tonne press in a 200 tonne press. They not only had it at 200 tonne clamp, but they had no mould protection set and no slow down on closing. The mould came out with the parting line all peined over like the head of an old cold chisel.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
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I have seen a broken platen where a long narrow mould was bolted in between the supports instead of across them. It was a 1200 tonne press so the owner was not at all pleased.
My rule of thumb was always 3 tonne per sq inch of projected area.
Always set the clamp to no more than necessary to prevent the mould blowing open during injection. This is not so much to prevent the mould being crushed as it is to save wear on the toggle pins, the pumps and to save power.
I have also seen a mould you could easily run in a 40 tonne press in a 200 tonne press. They not only had it at 200 tonne clamp, but they had no mould protection set and no slow down on closing. The mould came out with the parting line all peined over like the head of an old cold chisel.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
Hi Pat
I also have seen the results of a 150t mould in a 350t press - a cracked/scrap cavity! We had a customer who could not wait until we had a production slot to fit in his "now" lead time, so he got it run elsewhere. Took two weeks to make another cavity, by which time we could have easily met his requirements - which we did anyway. More haste, less speed!
We have all hydraulic clamp machines and I always drop the clamp force down to the minimum required to mould the parts. Saves energy (which most folk forget), wear and tear, and allows the tool to breath. Simples.
In my limited forty years experience, the biggest problems with running small tools in big presses is a) tool height (getting it to clamp at all) and b) material residence time, as big machines usually have big barrels and c) being able to have a shot stroke longer than the check ring is, otherwise you have no chance of maintaining a cushion or any shot to shot consistency.
H
www.tynevalleyplastics.co.uk
It's ok to soar like an eagle, but weasels don't get sucked into jet engines.
I also have seen the results of a 150t mould in a 350t press - a cracked/scrap cavity! We had a customer who could not wait until we had a production slot to fit in his "now" lead time, so he got it run elsewhere. Took two weeks to make another cavity, by which time we could have easily met his requirements - which we did anyway. More haste, less speed!
We have all hydraulic clamp machines and I always drop the clamp force down to the minimum required to mould the parts. Saves energy (which most folk forget), wear and tear, and allows the tool to breath. Simples.
In my limited forty years experience, the biggest problems with running small tools in big presses is a) tool height (getting it to clamp at all) and b) material residence time, as big machines usually have big barrels and c) being able to have a shot stroke longer than the check ring is, otherwise you have no chance of maintaining a cushion or any shot to shot consistency.
H
www.tynevalleyplastics.co.uk
It's ok to soar like an eagle, but weasels don't get sucked into jet engines.
patprimmer
New member
Yep.
All the above.
OP I hope your are observing that cl;amp can be adjusted to suit, but there are other problems.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
All the above.
OP I hope your are observing that cl;amp can be adjusted to suit, but there are other problems.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
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