[deadlykitten]

indeed arie, anyone wishes for rigidity, but sometimes there may be a weak fixture, or overhang on tool , or whatever

lately some o350 x 550 parts needed external turning with 0.02mm tolerance, after deposition of a hard layer, that simply distroys carbide inserts after 30-50mm, while better diamond tipped inserts would last a few complete passes, but with wear corections among the way

for example, final radial docs are like 0.3 0.2 0.1 0.07 0.05 0.02, while offset corections are aplied, and, to achieve the last 0.02, the tool offset is raised with 0.2mm, or something, thus, in orider to go deeper, the tool is raised there is no linearity between offset and real doc, as the normal aproach was initialy grinding, which is much more stable and finess

as passes are relativley long duration, is easy to loose track of corections, so a log is being kept

this is just a particular example, as, in general, every setup has an elastic and plastic behaviour; and rigidity occurs when elastic behaviour does not affect the tolerance but of course it drives me crazy, i wanna throw the thing in the dumpster, like you said .... but i just have to get it done, what choice do i have ?

.I used 2 mm on the Bridgeport VMC 800, 1000, 600, 610, Interact, Oerlikon Vector, Schies & Froriep, Kiheung, Basically every Heidenhain Operated Machine i ever worked on, but i also used the same 2 mm on Elora controled machines, and on Cincinnatti and Fadal Controls..

the background of the clearances that i discused here, is in conjucton with okuma's codes; is a result of long term homework about cycles times shortening technique, trigering seconds, tens of a second, or even less, each time scale having different aproaches

[arie kabaalstra]

In my book.. Such discrepancies between offset and dimension, call for a more Rigid setup, or even hardturning..but that requires a way different machine..


but, if Ceramics wear out that quicly, what kind of hardness are we talking about?.. I have done my fair share of Hardturning on a "regular CNC" with Kennametal MC2 Ceramics up to 63 HRc..without a hickup..

if they wear out that fast.. Cutting Speed is too high.. rather take some more time to Finish a part than to stop and measure every single part 4-5 times..

Like i always do: Rough out a part, until there is like 0.1 mm left.. then take the Finishing tool, and Remove the rest.. that should do the trick.

At the moment, i'm running lots of TItanium parts, and i use a roughing tool for most operations, except Grooving, I Drill the inside to a "Comfortable dimension, and only have to Bore out mere tenths.. every part comes out like it should.. and when the upper border of a Tolerance field comes in sight, appliying a little bit offset does the trick.. be one step ahead of the game!.. at all times. Compensate for wear before you're out of Tolerance..

[deadlykitten]

hy i have never work on titanium, how is it ?

if they wear out that fast.. Cutting Speed is too high

is not a regular part, roughed, sent to heat treat, then finished; no, is not that

is roughed, sent to aditive, rough, finish ... the aditivie layer surface is not continous, but interrupted, and this is a chalenege

also, is not possible to rough deep, as that will make the aditive layer loose contact, exfoliate, desintegrate

once the surface is clean, finishing begins, with smaller and smaller docs, and as the doc being < tool insert radius, the tool is deflected; deflection is caused also by hardness and big diameter

as cutting gets closer to final dimensions, the layer gets denser, more compact

attached is an offset chart, for the simple part; there are 2 parts, that must work togheter; please notice the zig zag that occurs near the end, as there the dimensions get closer and closer to the tolerance of 0.02 ... until now, those where being delivered by grinding; and the 2nd part is much more chalenging; as for cutting specs, those are regular, normal, no rush ... a rush may break the insert mid-cut and such things are harder to correct when they happen

i don't get bored