chatter and harmonics

[C Schwarz]

There comes a point in every tool makers, machinists,programer etc. career when he or she realizes that cutting material is all about sound.

I mean feeds and speeds are the foundation, but there is more to it than just numeric values.

Some complex milling set ups have a high affinity for developing chatter harmonics. Sometimes there is no way around it. If one were to apply recomended chip loads and surface footage to this setup. The result would be a squeely co-worker call followed the inquisitive probe by the op. manager that is rivalled only at the proctologist office.

I have been experimenting with tones generated by the cutters in an ideal setup. I have made some interesting discoveries.I hope to one day reach a point were I may compare the tone generated by a new setup, to one I know is ideal for that material, speed and feed,cutter etc. I also hope to be better able to increase cutting speed and maintane cutter life with this process.

Ideally one should be able to in effect "tune" the cutter to its best feed and speed for that givin situation based on the ideal tone.

 

My question to you forum members is has anyone ever undertaken such a study?

I would appreciate any thoughts or experiances one has had with cutter tone and any advice too.

One more thing does anyone have an ocsilliscope for sale please e-mail me if you do.

[Guest]

This month Modern Machine Shop has an article about a University of Florida assistant professor, Tony Schmitz, who is studying just what you are talking about. Here is the link.

 

link

[limitless creativity]

There are a few companies out there that check the harmonics on the cutter in the spindle to check the frequency, they put a sensor on the cutter, the sensor is wired to a computer, then you would tap the cutter and the frequency would be sent back to the computer and genterate a wave that would tell you the optimum range on speeds. this is just the basic format. You would have to contact the company specifically.

 

Mike

[Jack Mitchell]

C. Schwarz,

 

The observation of sound is an excellent argument; I believe that Pythagoras and associates actually observed sound as a mathematical relationship with rational numbers.

 

Harmonics have always been with us – It’s that familiarity that we can hear through an office or cinderblock wall – the under/overfeeding event, the ugly sound of poor machining set up and operation, or worse, the needless beating of a fine machine tool at the hands of a hack programmer/operator or ”I just push the friggin button/operator”!

 

Please don’t get me wrong, for I truly admire another perspective on machining to its fullest potential.

 

Regarding the perfect pitch or harmonics, this can never exist – it’s the fun of learning and applying - the thought of a perfect program can also never exist; this is what keeps our sanity; every so often we look upon our process as the Mac daddy solution – just when we think we have it all, some 20 year old, kicks things up a notch & teaches us another cowboy approach.

 

My argument is that I choose to deliberately consume a tool in order to manufacture a given workpiece in the quickest most efficient method; I do not choose to look upon optimum tool life given rpm or depth of cut – my conscious effort is to get the job done - Fast!

 

No harm intended, just another opinion on an interesting subject, I do indeed have an oscilloscope and would never, ever, consider parting with it.

 

Best Regards, Jack

[Chris Rizzo]

Yeah, check out this month's Modern Machine Shop...It has a pretty interesting article on "harmonics"....