Mechanical press die/tool life

[prnkshrn]

Hi all,
My first ever post here.
We have a Seyi 300 ton mechanical press in our factory that runs a progressive die (punching, lancing, forming operations) to produce parts. We want to be able to realise with confidence when the punches or some other tools become dull or lose their strength.

To do this, we intend to use software that provide tonnage signatures (images attached), which is a graph of load on strain gauges attached on the press versus degree of stroke or time. These tonnage signatures are collected at regular intervals and compared with performance curve of the press (same graph with good condition tools) and analysed for discrepancies. If we find a discrepancy like an increase in tonnage values, we can confirm that the tools have become dull/weak and require maintenance/replacement.

Is this a good way to go about and can we expect feasible results?
Has anyone used a software such as this?
All suggestions are welcome.

Thanks in advance!

 

[Screwman1]

Check out the "Impax" monitors, they are already set up to do just this type thing. No need to reinvent it.

 

[prnkshrn]

Thanks for the reply.
Well, we already have tonnage monitors attached to the press that work fine, so replacing them just to have tonnage signatures is much more expensive than the software itself.
What we basically wanna know is, will this work?
Will we obtain distinct discrepancies on the graph over time which would be due to the tools going dull?
In the past, we've had tools break off the punch plate and falling on the die, resulting in heavy damage to the die block. If we are able to monitor the wear on the tools, we can prevent this from happening. Workers examining the tools after every run is not an option for us at this moment.

 

[ornerynorsk]

The accuracy and resolution of your tonnage sensors are going to be key. I realize your attached graph may be just a representative sample, but you're not going to see a 5x spike with dull tooling. Just out of curiosity, what tonnage does it take to run the tool-set in your 300 ton press? One cautionary word about SPC and having the system tell you when your maintenance interval is up, don't let your operators become lazy and slack off on process consistency. Material cleanliness, oiling, slug pile-up or jamming, all these things will have a huge impact (no pun intended) on tool wear and breakage. A QC sample to inspect your cutting bands, burring, and formed surfaces on a regular interval is every bit as good and reliable as tonnage monitoring, in my opinion.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[John2025]

It seems like that would work for the overall condition of the die, but it seems likely that some punches will wear faster than the rest and I don't think you'll be able to see that small of a change hidden in the overall reading

 

[EdStainless]

Measuring the geometry of the parts should be part of this.
The radius in corners or the height of burrs is very closely linked to tool condition.
We used to take a stack of parts and measure the total height, this was easier than trying to measure single part burr.
With optical devices this should be straightforward to do.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[prnkshrn]

Thank you for your replies everyone.
"Just out of curiosity, what tonnage does it take to run the tool-set in your 300 ton press?"
Well, we use many dies and tools on the press and every set gives different tonnage values, it can range anywhere from 180-210 tonnes.

 

[berkshire]

One thing to bear in mind, is that a small diameter punch in an overall setup like that, will not show extra tonnage on the overall effort, unless your sensors are extraordinarily sensitive. For that, as Ed says you should be monitoring the condition of the parts. A bad burr on a part will be evident long before the machine shows extra tonnage. Before the advent of high speed CNC turret presses I used to run 4'-0" square Whistler die sets sometimes containing as many as 80 individual punches. Monitoring the produced parts was the only efficient way of seeing what the individual punches and dies were doing.
B.E.

You are judged not by what you know, but by what you can do.

 

[prnkshrn]

Thank you for your inputs.
How did you deal with tool breakage? Did you prevent it altogether by regular maintenance?
We were also hoping that the software would help us with that as long as the tool does not break without showing any signs.
We've also had a problem of springs breaking in the past (due to a design fault in the die set), which also destroys the stripper and punch plates. We believe that when some springs break, it will be reflected on the tonnage signature.

 

[EdStainless]

Our presses were old and fairly primitive. We had a microphone clamped to the die set.
At setup we would dial in the sound level at stamping to zero.
During operation if the noise level increased (or decreased) too much the press would shut down.
I don't recall us ever braking a spring, we did a lot of maintenance on tooling.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[berkshire]

prnkshrn
With a whistler die set it was fairly easy , you just removed the individual punch and die with stripper from the setup and changed it . The biggest problem with that type of setup was slug accumulation , we sometimes used an air blow off system to get rid of them.
Now I realize that system was a lot simpler than your progressive die set, but as far as tool care goes the same basic principles remain.
B.E.

You are judged not by what you know, but by what you can do.