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Determining single point diamond machining parameters for new material?

Determining single point diamond machining parameters for new material?

Determining single point diamond machining parameters for new material?

(OP)
Hi there,

If I have a new material in my shop and I want to single point diamond turn it, obviously, I don't really want to go through the hassle of machining different diameters with different parameters, taking the workpiece to a laboratory and analysing the surface parameters.

How do people machine something without using a trial and error method i.e. a best first guess of feed rate, cutting speed, depth of cut, etc?

RE: Determining single point diamond machining parameters for new material?

(OP)
I've not idea how anybody could machine a material with a single pole double throw switch... There really should be no confusion that I'm talking about single point diamond turning...

RE: Determining single point diamond machining parameters for new material?

For ordinary machining, the cutting tool insert manufacturers can provide decent first guess parameters for machining a given material with a given insert. From there, you keep track of the material removal rate and finish as yo9 adjust feeds and speeds, hopefully in a fairly organized series of relatively few experiments, and you might duplicate some of the experiments as new lots of material and new lots of cutting tools arrive, just to be sure you're always on the same page.

I'd imagine that someone has a fair amount of information about diamond turning copper optics, but for other materials, you might be on your own.

Are you allowed to reveal what you're trying to do, with what materials, and what problems you're trying to solve or avoid?



Mike Halloran
Pembroke Pines, FL, USA

RE: Determining single point diamond machining parameters for new material?

(OP)

Quote (MikeHalloran)

Are you allowed to reveal what you're trying to do, with what materials, and what problems you're trying to solve or avoid?

I should note that the general methodology is to look at your surface finish, as you state... but what if you can't do that?

It's more of a philosophical question. What methodology could you use to determine the machining parameters of an unknown material without analysing your previous cuts? This is made even more complicated when the material is extremely brittle and parameters must be more accurate to avoid slipping/plowing.

RE: Determining single point diamond machining parameters for new material?

The only brittle material with which I have any experience is Macor.
In machining that, you can't just decide to cut an arbitrary number of microns off, because Macor doesn't shear nicely, like e.g. copper. You have to cut about .001" off, or nothing, or maybe .002", because Macor sort of fractures into little particles corresponding to its grain size, as the grains get 'hit' by the cutting tool. You also have to provide strong suction near the cutting tool so the little hard particles don't get into your machine's ways, or your lungs.


If you can't measure/observe your workpiece, the next best thing probably is to measure observe your swarf/chips/detritus. For metals, you want a chip that looks like a comma glyph, and comes off hot, so that most of the machining work goes into heating the chips, not the workpiece. For whatever you're machining, I don't know what a good chip should look like, but maybe you can figure it out.

Mike Halloran
Pembroke Pines, FL, USA

RE: Determining single point diamond machining parameters for new material?

(OP)
That's an interesting idea. It is well known that UNDEFORMED chip thickness plays an important role in determining whether ductile-regime machining is taking place, which is the only way to machine brittle materials. I am not sure about deformed/post-machining chip thickness though... I'll investigate.

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