Gummy metals cut better when marked with Sharpie or glue

[FEM2008]

I think this would be very useful for this community. Research is done at Purdue University. Article can be found here: https://www.designfax.net/cms/dfx/op...earticle&pn=03

[Toolmaker51]

Alternatives maybe; but effect not different than common cutting fluids. A layer of material prevents rebonding to parent metal facilitated by heat generated in cutting. It's counterintuitive but lubricants can do this too, just not as effectively. Wax, lard, kerosene, moisture displacing aerosols, even vegetable oil just some of the age-old remedies.
Another reduction in heat is using proper cutters. Insert and brazed carbides do not 'cut' per se; they push material off. HSS with correct clearance and rake generates a shearing action beneficial to soft materials. Wondering also, is theory-geometry-practice of tool grinding even a topic anymore? Seems like all the majority knows about is carbide.
Give students and professor full annealed aluminum and have them give it a go with magic marker or glue stick, deflating the results.

[FEM2008]

Looking the videos, the action of the chip flow with the colored bands reminds me of laminar vs turbulent flow over a wing. It is important to keep in mind here that the effect they observed works with very small depth of cuts (a few thousands). I can see that adding some material on top with different strain behavior-such as glue-changes how the chip "micro" bends and have an effect, but with other applied materials, such as alcohol, there must be a different mechanism that's working. Meanwhile, adding a layer of Dykem or even superglue before a finishing cut is easy enough to do and try.

Another interesting finding from the paper is that alcohol seems to work for some aluminum alloys, but it does not work on other metals. Stephan Gotteswinter did a video not too long ago were he used alcohol as a cutting fluid for some CNC machining on aluminum ("More CNC Router Adventures" from a couple of months ago"). The initial study was published 2 years ago with a recent update that I posted here, so it is plausible that some have implemented this already.

[Toolmaker51]

Just about anything will generate the effect; contaminating the bond of heated material to parent, or cooling the swarf below a temperature willing to adhere.

Lab experimentation demonstrates an effect, yet probably far lower than what would occur in a production environment. Everything comes into play beyond material alone, depth of cut, feed rate, RPM, cutter type, distribution and coolant variety, just for starters.

[Floradawg]

Man, I feel like I'm sitting in a physics lecture. Seriously though, it's apparent that y'all know what time it is.

[Toolmaker51]

Well, here it's lunchtime, with one-fingered typing.
And not so much physics as metallurgy, mechanics and materials.

[Floradawg]

Enjoy your lunch!

[Toolmaker51]

Enjoy lunch? Goes without saying.
As someone far more clever than I said, "Enjoy every sandwich".
He understood this, sadly, before the rest of us.

[FEM2008]

Enjoy lunch? Goes without saying.
As someone far more clever than I said, "Enjoy every sandwich".
He understood this, sadly, before the rest of us.

Zevon fan?

[Toolmaker51]

Yes, top tier; one of many who can turn a phrase, and strike a chord.