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By serge.nelissen

March 17, 2019, 10:57 am

Broken End Mills

Hi,

I broke 4 carbide end mills :-(

Spring steel 200 HB
carbide end mill 4 mm, stick out 20 mm, 2 flutes
DOC 5 mm
WOC 4 mm

Suggested feed is 39.46 mm/min, I used half of that.

I had chatter and broke 4 mills and yet the tool torque calculated by HSM advisor is 50%.

What am I doing wrong?

Thanks,

Serge

Hsm.png Hsm.png

Answers:

Pages:(1) [1]
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Eldar Gerfanov

March 18, 2019, 9:47 am

Hello,

There are several compounded reasons your endmills broke:

1) You are sticking your end mills too far out.
16 mm is way too long for a 4mm endmill. Is your flute also 16mm long? If so, you should reflect it in the tool data.

2) You entered your own custom DOC (5mm) instead of the suggested one 1mm.
Why is suggested DOC so shallow? Because your end mill is way too long.
HSMAdvisor will suggest you a good safe DOC according to your cutter parameters.
You may choose to use your own value, but then at some point it can not compensate any more and will cause excessive chatter that will quickly break the end mill.

3) 2 flute end mills are not ideal for steel. Try to get a 4 flute with short flute and if you need it to stick so far out, then use the 6mm shank endmills like in the second screenshot

Please check the screenshot:
Your situation with proper DOC
vs
What i would do with suitable tooling

Please let me know if you continue having any issues.

Best regards.

2FL 1mm DOC Capture_4mm_1DOC.PNG 4FL 10mm Shank Capture_4mm_10mm_Shank.PNG
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serge.nelissen

March 19, 2019, 4:17 pm

Hi Eldar,

Can you answer my question about why deflection and torque don’t exceed the limits and yet I broke the mills?

Thanks,

Serge

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Eldar Gerfanov

March 19, 2019, 6:24 pm

Deflection and Torque calculations do not consider so-called positive feedback.

When you get chatter and the stiffness of the cutter is very low, it often turns out that the end mill may bite off more than the programmed Feed rate. Additionally a 2 flute end mill has very uneven load as it rotates.

Long story short. Try to run at DOC suggested by the calculator.

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serge.nelissen

April 2, 2019, 8:35 am

Hi Eldar,

Do you consider implementing the max DOC and WOC supplied by the manufacturer?

Thank you,

Serge

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Eldar Gerfanov

April 2, 2019, 9:51 am

Quote:"SERGE.NELISSEN"
Hi Eldar,

Do you consider implementing the max DOC and WOC supplied by the manufacturer?

Thank you,

Serge


Yes I do consider that. But also I must consider the overall value for all users and the cost of building and maintaining a feature that is already (sort of) covered by other means.

Please provide me with links to tool manufacturers recommendations regarding maximum DOC/WOC to help me decide.

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serge.nelissen

April 2, 2019, 11:07 am

Hi Eldar,

I can’t provide you links because on their web site they don’t show those figures. Only in the printed catalogue.
But, in fact it’s simple... WOC can vary from 0.03 diam to 1, DOC from 0.1 diam to 2.

Sorry,

Serge

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Eldar Gerfanov

April 2, 2019, 12:03 pm

Quote:"SERGE.NELISSEN"
Hi Eldar,

I can’t provide you links because on their web site they don’t show those figures. Only in the printed catalogue.
But, in fact it’s simple... WOC can vary from 0.03 diam to 1, DOC from 0.1 diam to 2.

Sorry,

Serge


Unfortunately it is NEVER that simple.
DOC/WOC depends on multitude of factors. Main of which are number of flutes, material being machined, chip load and stick out length of the cutter.

Do you suppose we should keep track of max doc/WOC for various materials as well? A feature like that is not going to be used by anyone including you.

HSMAdvisor already accounts for all of that behind the scenes and boils it down to one single value "Performance Value" that can be adjusted from its default value by the slider and saved with the tool and each material-specific cut.

The way to work it is to select your material and the exact cutter setup.

Enter the manufacturer recommended feed and speed.

And then (if needed) adjust the Performamce Value to represent what the manufacturer recommends.

Then save the tool into the library.
With this done you will have near-perfect calculations for all other materials with this tool type.

Best regards.

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Eldar Gerfanov

April 2, 2019, 12:07 pm

PS.

Please do not think I am trying to shun you down or anything of sorts. I truly thank you for your feedback and think it is valuable.

I am just trying to gage the feature's worth before I commit my time to it.

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serge.nelissen

April 2, 2019, 5:56 pm

No Eldar, I,don’t think you try to het rid of me. You are kind and helpful.
And, it is simple anyhow. The manufacturer doesn’t make any difference between different materials. He just makes some suggestions about max WOC and DOC. You could calculate your DOC and WOC and LIMIT it to.the sugested values from.the manufacturer.

Agree?

Serge

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