Diving Into Chip Thinning: In The Loupe TV Ep.13

A common phenomenon that many machinists experience at the spindle is chip thinning. This occurs when step-over is less than 50% of the diameter, which causes the chips to be formed less than what the tool is programmed to remove. Tooling is specially engineered for certain chip thickness, so it is essential to ensure it is correct, to avoid premature tool failure. Join In The Loupe TV's "Cutting Tool Counselor," Don Grandt, as he provides tips and tricks on how to simplify the process of combating chip thinning, so you can get the most out of your CNC tooling.
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[@zney11]

Another great video!

[@KevinHarveyBarratt]

10-2-2 5-2.5-2.5 Interesting way to prevent chip thinning. I have not increased tool velocity in compensating. I've always kept the SF in relation to the suggested coating for the material. I can understand that the amount of heat will change though, but the cutting edge still has to be in contact with the material at the speed that the coating is rated for. It's a habit that will be hard to break.

[@dongrandt372]

No wrong way to approach it Kevin. But as the radial gets lighter we do generate less heat based on the amount of time we are spending in the material per flute. It is a small amount but enough to bring the sfm up to increase your MRR. Tool life is the X factor though. Its about the more we know, the more we can manipulate. Thanks for the Comment. CTC

[@sdavito]

If the chip data is based on an ae of up to 30%, will your method work? If not, is there an easy way to calculate? Would I divide .5 by .3 (1.66) and use that number as a base to use in your formula?

[@punkdudex69]

Good general rule for starters. I think chip thinning is a good approach to apply for deep axial roughing.
I would be interested in learning more abbout optimzing chip thickness and sfm with finish passes as well. I have some rules i have had success with but i feel like there is more of a "gray" area when finishing parts for speed and tool life

[@CuttingtoolCounselor]

I like a 3-5% of diameter for finishing… pending LOC. Thanks for the comment! Ctc

[@bigboytroy]

@@CuttingtoolCounselor and using 5-2.5-2.5 rule for finishing pass Aswell?

[@muralinaik6511]

Thanks for the Combat rule..
Don.. U r the ruler! 😊
What a great knowledge..
Simple and effective explanation..
Thanks for the session🙏
And finally...
What about the rule with spring passes!?

[@dongrandt372]

Love that question! I am the spring pass King! OK there is a massive amount of Chip thinning going on when we take a spring pass, but a spring pass is to do one thing and that is to straighten the wall. Lesser of two evils. A spring pass, believe it or not is more of a burnish not a cut. It removes the remaining stock at the bottom of your cut using rigidity of the tool. Death Taxes and Spring passes... Unfortunately. ( Disclaimer is that it depends on your Print tolerances and wall straightness. Just understand most Chip thinning is explained in Roughing ops...)

[@muralinaik6511]

Thanks don!

[@user-yn6oz5pl9c]

I never take Spring Passes. It Dulls the cutter.

[@hamzanawaz7945]

💥

[@hectordominguez7143]

What do you do if the SFM increase puts you outside your machines RPM range?

[@dongrandt372]

Hello Hector, Great question. Our SFM is always limited by our RPM of our machine. SFM is based on Diameter and as the diameter gets smaller we are limited on how high we can go.. Two things with this. The Feed Per tooth is always based on the RPM not the SFM. So if we are limited on SFM we are still going to be able to control the chip at the cutting edge. Slight sacrifice in tool life when we cant use all of the SFM because of the required heat needed to make the the chip at point of contact but totally acceptable. #2 is you could look at a Speeder Head or a HS spindle. This will allow you to get the correct recommended SFM for smaller tools. Hope this helps. CTC

[@user-yn6oz5pl9c]

Meet me at the bar. We'll drink about it.

[@frankmoats1844]

Re your chip thinning formulas, doubling the sfm doesn't seem right. For example cutting titanium, doubling the sfm will burn the tool up

[@dongrandt372]

Frank I understand your concern, but lets take a look at Ti.. In our book we recommend cutting Ti6al4V at 160SFM and .0035 IPT.. With a HEM toolpath I would have no problem running 320 SFM up to 400SFM and .006-.007 IPT at a 10%Radial. Its just a good Starting rule for chip thinning. We also need to consider a lot of other factors that encourage SFM.. My video on CTIC and SFM also could help with understanding better. Thanks again for participating with Comments. If you have good parameters for TI please share sir.. CTC