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By Blue_Chips

May 3, 2014, 8:30 am

Feed not updating after DOC of from .050 - .100 inch

Eldar
Noticed this morning that the feed update block updated perfectly until the DOC went below .100 inch, at that point the value remained unchanged even down to .010 inch. When this occurs, seemes to happen at a different DOC depending on the size of the couple cutters tools I checked. Both end mills, one 2.00 diam and one .375 diameter.

Also, the DOC, when input using the .375 end mill remained at the expected input value till it went above .750 then all input defaulted to .750

Ken

Answers:
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Eldar Gerfanov (Admin)

May 3, 2014, 6:54 pm

Hi Ken,

Instead of following rules of thumb like "double the feed when doc is half"
HSMAdvisor is using a rather complicated algorithm to calculate those things.

Without going too much into detail.
When your DOC is less than ideal (suggested by default) feedrate will increase depending on hardness of the material and its horsepower requirement.

And chipload will increase more for soft materials and less for hard ones.

But it is also limited, otherwise you would get infinite high chipload for doc close to zero.

In other words it tries to behave like a manual machinist would. It increases chipload when taking shallow passes, but not to the point where cutting edges chip.

I did not get the second question.
Can you explain better or maybe post some screenshots...

Working right now on your other posted issues .

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Blue_Chips

May 3, 2014, 8:01 pm

Hi Eldar,
On my first concern, I can live with it.
Although it doesn't seem extreme for a 3/8 endmill to take a finish pass of .005 which when input doesn't make any difference in the feed to keep chip load up.

With regards to the second, I believe the same thing is going on with the dept of cut as with the feed, it is defaulting to a more expected DOC when the input DOC is extreme, as in inputting .900 with a 3/8 end mill in this case.

The depth of cut wasn't bothering me, I mean when was the last time I took a .900 cut with a 3/8 end mill anyway LOL, so it defaults to .750 which is more then would be used.
My thought were only that if it was a math problem internally the issue might show up elsewhere, I'm sure all is well in that regard now.

Thanks
Ken

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Eldar Gerfanov (Admin)

May 3, 2014, 8:40 pm

There is nothing stopping you from going deeper per pass other than the flute length.
DOC is simply limited by the flute length in your case.

It is important to carefully enter ALL of your known tool parameters IF they are different from default.

Things like Flute Length, Shank Dia, Lead Angle (Taper of the cutter) are there not just for show.
They tremendously affect a lot of things including speeds and feeds.

Other fields like Helix angle do not affect things as much, but flute length , diameter and shank size are very important.

Standard Length of cut DOC Limited by Lenght of cut.PNG Longer Flute length allows for deeper DOC DOC Limited by Lenght of cut2.PNG
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Eldar Gerfanov (Admin)

May 3, 2014, 8:45 pm

PS.

Actually if you look carefully at both screenshots posted before, you will notice that in the second case where flute length 1", maximum MRR is 10% lower than where flute length is 0.750" (10.0in^3 vs 11.0in^3 respectively)

Just 0.25" of longer flute warrants reduction in material removal rate.

So, using proper tool data is important to get proper results on many levels.

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Blue_Chips

May 3, 2014, 8:48 pm

Ah,
OK, I see the relationship now, still learning the ropes with it.

Thanks
Ken

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Eldar Gerfanov (Admin)

May 3, 2014, 8:54 pm

Wow that was a fast response from you!

Maybe i should enable email alerts, to let people know when they get a response on their topics.....?

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Blue_Chips

May 3, 2014, 9:08 pm

Quote:"ADMIN"
Wow that was a fast response from you!
Maybe i should enable email alerts, to let people know when they get a response on their topics.....?


Definitely, save the time of checking and finding nothing there.

Ken

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