turning low carbon steel : 550M/min 2.6doc f0.35 spindle load 65% ; Genos


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Thread: turning low carbon steel : 550M/min 2.6doc f0.35 spindle load 65% ; Genos

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    Default turning low carbon steel : 550M/min 2.6doc f0.35 spindle load 65% ; Genos

    hello, i recently started a setup, and i am still adjusting it

    i am turning some low carbon steel, from diameter 127 to 112 :
    ... roughing at 1400rpm, f0.35, doc2.6 ( 550M/min )
    ... finishing at 2000, f0.22, doc1 ( 700M/min )

    machine and inserts are performing nice, thus there is a nice balance

    problem is that material is not uniform, and some parts are machined ok, while on others i have a lot of long chips, that are wrapping very-very fast arround tool and part

    to handle this :
    ... i started using higher clearances between passes: when tool reaches end of cut, instead of X0.6 Z0.3 G91 i have X80 Z0.3 G91: like this, wrapped chips may fall from the tool
    ... i started cutting discontinous : instead of G01 Z-50 i use "G01 Z-20" + "Z-19" + "Z-50", so to break the long chips along the cut
    *in the end, the long chips did not dissapeard completly, but at least i reduced the wraping frequency

    material face is tilted, from the band saw, and at this speed, when the insert makes contact with the material, it vibrates, etc : to handle this, i enter smooth at f0.1, and after that i accelerate the feed inside the material

    please, what else should be done ? kindly


    higher rpm = lower resistance; check this from the china-town ( chun li, li gung, jet li, bruce lee, ): This can be explained that the high-speed cutting process is much faster than normal cutting process, and the chip-tool interface may occur mutation slip and adiabatic shear which inhibits the occurrence of the stain hardening process, so cutting forces are decreased with the increase of cutting speed

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    Last edited by deadlykitten; 11-02-2018 at 10:56 AM.
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    Default Re: turning : 550M/min 2.6doc f0.35 50%spindle_load, in low carbon steel; Genos

    If your insert is designed for the material you are turning and you run the lathe withing the insert specs, the chip breaker should work and you should get nice chips.

    Have you checked the play in the machine, carriage, apron, cross slide, top slide and spindle!

    Vibration (chatter) means: to fast, to much load, not rigid enough, play, dull insert, wrong clearance angle, etc

    But maybe you are turning the wrong type steel, cold / hot rolled steel, steel with a lot of pollutions.



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    Default Re: turning : 550M/min 2.6doc f0.35 50%spindle_load, in low carbon steel; Genos

    hello i am not referring to those classical vibrations that lead to wavy part aspect, but to the vibrations caused by cutting edge making contact with the part

    thus the shock when tool enters the material, especially at 1st cut, when it hits the surface layer ( the crust )

    i tried to minimize the number of such contacts, and also reduce the specs in such areas



    material is not uniform, and these differences are causing effects that are increased with higher speeds; if i would cut it at lower rpm, etc, i would definetly break the chips more often, but also program time would be longer



    i am looking for some tips to eliminate ocasional wrapping at higher rpms

    i once heared that high pressure cooled coolant does wonders, but i don't have such equipment / kindly

    Last edited by deadlykitten; 11-02-2018 at 12:15 PM.
    Ladyhawke - My Delirium https://www.youtube.com/watch?v=X_bFO1SNRZg




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    Default Re: turning : 550M/min 2.6doc f0.35 50%spindle_load, in low carbon steel; Genos

    especially at 1st cut, when it hits the surface layer ( the crust )
    You have probably done it already but:
    • Reduce the (entry) speed (X) at the first cut
    • If you have a tool changer, use a different tool for the first cut
    • Try to run with / without coolant. If you allready use coolant, I don't think extra cool coolant will help!


    i am looking for some tips to eliminate ocasional wrapping at higher rpms
    Just stopping the feed for a short period of time would break the chip.

    material is not uniform
    That is a "show stopper" . If it is not uniform in layers (X) then adjust the cutting to each layer. If it is not uniform in zones (Z-direction), adjust the cuts for each zone.
    If, in the end, you have to lower the turning speed, you could try a larger cut/rpm or just cut deeper to partially compensate for the extra duration. But I think you all ready are stretching the limits.



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    Default Re: turning : 550M/min 2.6doc f0.35 50%spindle_load, in low carbon steel; Genos

    hello hfjbuis

    If you allready use coolant, I don't think extra cool coolant will help!
    idea is to use coolant force to break the chips, or at least to reduce the wrapping phenomen

    this requires high coolant pressure system, and at least one coolant nozzle pretty close to the cutting edge

    if coolant nozzle is away from the cutting edge, then coolant force is lost, because it is scattered

    on a normal setup, you simply put a nozzle, and look for coolant to flash the cutting edge, without much care if a lot of coolant is not hitting the cutting edge

    depending on setup, some tools require high coolant debit, while other require low coolant debit, that will actually wash the tool, keeping it "flooded"

    Just stopping the feed for a short period of time would break the chip
    yup, i am doing this type of peck turning; more precisely, i don't stop, because this will lead to tool friction, but going diagonally backwards X+0.3 Z+1.2 G91

    is like a mini-machine-gun

    If, in the end, you have to lower the turning speed, you could try a larger cut/rpm or just cut deeper to partially compensate for the extra duration
    yup, i am looking for another winning combination; ZS loads are pretty high, so i will simply shift the load from one axis to another; i don't know / kindly

    Last edited by deadlykitten; 11-02-2018 at 04:14 PM.
    Ladyhawke - My Delirium https://www.youtube.com/watch?v=X_bFO1SNRZg




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    Default Re: turning : 550M/min 2.6doc f0.35 50%spindle_load, in low carbon steel; Genos

    hello hjfbuis, i played a bit with this setup: material is not uniform, so i could not keep the high rpms on all the time

    in the end i almost halved some rpms, and increased docs wherever possible

    walter tiger's performed better

    to gain back some time, i had speed up the milling operation ...

    on many setups i hit into trouble because of material not being homogenuous, so i lower the specs

    a bit here, a bit there, you know, the routine kindly

    Ladyhawke - My Delirium https://www.youtube.com/watch?v=X_bFO1SNRZg




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    Default Re: turning : 550M/min 2.6doc f0.35 50%spindle_load, in low carbon steel; Genos

    Hello deadlykitten,

    I have given your problems a thought. If you stop cooling, the chips will get hotter and maybe break more often. But i guess you will get some other problems in return.

    If you need high pressure cooling, to blow the chips away, you could use a pressure washer like karcher sells. For a few bucks, you can try and see if it helps.

    Have fun,

    Huub



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    Default Re: turning : 550M/min 2.6doc f0.35 50%spindle_load, in low carbon steel; Genos

    hello, i restarted this setup recently

    i changed it a bit here-there, but mostly there is a change that targets a classical operation : facing + chamfering + od, and this change made a difference

    generally speacking, facing & chamfering are operations with smaller doc, and they are done at the begining

    if doc is small, chips won't break, so the tool will begin cutting the od with wrapped chips arround it

    also, if the chamfer is 0.5x45*, it requires a small feed ( that won't break the chips ), so the spindle to rotate a few times; otherwise, if the feed is high ( so to break the chips ), then the chamfer won't look estethic

    so i re-maped this toolpath; pls check attached :
    ... black : rapid ( not cuting ) movemenents
    ... yellow : feed ( cutting ) movements

    now, chips are wrapping less often, tool is clean : stability has raised i believe that this is the simplest change that i made so far, with nice effects

    spindle load is arround 70 - 85 %; if i would replicate this setup on a dual turret lathe, it may need a stronger spindle

    setup requires more attention, because inserts are breaking suddenly

    i use walter 6059952; specs are attached / kindly

    Attached Thumbnails Attached Thumbnails turning low carbon steel : 550M/min 2.6doc f0.35 spindle load 65% ; Genos-untitled-jpg   turning low carbon steel : 550M/min 2.6doc f0.35 spindle load 65% ; Genos-specs-jpg  
    Ladyhawke - My Delirium https://www.youtube.com/watch?v=X_bFO1SNRZg




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    Default Re: turning : 550M/min 2.6doc f0.35 50%spindle_load, in low carbon steel; Genos

    I have looked at the insert specs. You can run 5 times the speed my (hobby) insert "allows" and they are 7 times more expensive.

    I guess the insert breaks at the chamfer pass when the insert hits the rough face and the cutting depth (first pass) changes from low to high to low (edge). If so, you may be hitting the resonance frequency of the tool or workpiece. A small change in feed, higher or lower, may solve this.

    Because you are not turning in one continues path, you could get a small burr at the chamfer edge that is not effecting the OD.

    The new tool path is slightly less efficient!

    Great to see that small changes can solve large problems.

    Thank you for the update, it clarified a lot.



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    Default Re: turning : 550M/min 2.6doc f0.35 50%spindle_load, in low carbon steel; Genos

    hello hjfbus so far, i was told once that okuma's are rigid enough to go 2x faster then the recomanded speed

    You can run 5 times the speed my (hobby) insert "allows"
    i read it many times, but only now i understood it : you mean that i go 5x faster than your real setup

    so far, i thought that you sugest me to run each insert 5x faster than the recomandation : something like, if on the insert box is written 170, i may go 5*170

    and, by hobby, i believed that you do this all the time, like a hobby

    so i said to my self : this guy pushes setups like crazy

    they are 7 times more expensive
    pls, what is their price in your area ? 10euro / insert

    those inserts are for steel with low carbon, so this is why they can achieve such high speeds

    for steel with normal / higher carbon, kyocera has a nice product; pls check attaced : 300M/min is standard recomandation

    to spare you some time, try to test 2-3 inserts, or buy a box of wnmg080408ph ca525 ( attached pdf, bottom position )

    I guess the insert breaks at the chamfer pass when the insert hits the rough face and the cutting depth (first pass) changes from low to high to low (edge).
    no, it does not break there, because it is entering the material at V300 F0.1, thus lower specs to reduce the entrance shock

    it breaks on the od, where it is at V500-600 F0.35

    If so, you may be hitting the resonance frequency of the tool or workpiece
    no, on this setup i did not resonate; but i did once, with grooving inserts width 6mm entire machine started to vibrate

    The new tool path is slightly less efficient!
    yes, it is a bit longer, but there are much less machine stops, so to clean the tool

    at this point, i feel i coud go a bit faster, but if the operator is not paying atention, it may blow up the toolholder

    it is hard to follow this setup when there is noise, and if you look at load monitor, so to see when the effort raises, it is too late; it requires a trained person

    Great to see that small changes can solve large problems


    it is kind of a luck, and this time it worked / kindly


    Attached Thumbnails Attached Thumbnails turning low carbon steel : 550M/min 2.6doc f0.35 spindle load 65% ; Genos-01-png   turning low carbon steel : 550M/min 2.6doc f0.35 spindle load 65% ; Genos-02a-jpg   turning low carbon steel : 550M/min 2.6doc f0.35 spindle load 65% ; Genos-02b-jpg  
    Attached Files Attached Files
    Ladyhawke - My Delirium https://www.youtube.com/watch?v=X_bFO1SNRZg




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    Default Re: turning : 550M/min 2.6doc f0.35 50%spindle_load, in low carbon steel; Genos

    I can't find this (walter 6059952) insert in Europe but could order them by E-bay https://www.ebay.com/itm/Walter-Valenite-6059952-Insert-Pack-of-10-/232878333973 for about $20,-- a piece. My local shop mainly sells some Sandvik inserts $4 a piece. My lathe(s) can't handle the speed needed to run your inserts within spec and my neighbors wouldn't appreciate the noise it could make.

    I only make prototypes and time or finish is never an issue, only the dimensions should be right. My inserts do about 90..180 m/min but most of the time I run slower and use HSS tools or CCGT inserts (yes on steel) for 0.01 mm doc.

    I wasn't aware that production is so challenging and for success you need a bit luck and a lot perseverance!

    Thank you for the information,

    best regards, Huub



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    Default Re: turning : 550M/min 2.6doc f0.35 50%spindle_load, in low carbon steel; Genos

    hello

    I can't find this (walter 6059952) insert in Europe but could order them by E-bay
    i also checked, and it seems that there is no walter/kyocera dealer in netherlands

    try intemediate vendors, maybe hoffhman ?

    arround here, both inserts are cca10euro

    My lathe(s) can't handle the speed needed to run your inserts within spec
    no worry, is not always about keeping it within spec; lower rpm means higher feed and/or doc

    however, with such inserts, you should observe longer tool life, thus the tool is more reliable, even if it is used at a lower speed

    I only make prototypes and time or finish is never an issue, only the dimensions should be right
    with shuch short setups, is a different challenge

    so far i run mainly long series ( weeks / months ), so i have conditions to test different inserts

    0.01 mm doc
    generally, i work with bigger doc, but the cnc spits all parts with dimensions inside 0.01 tolerance : for example, if part dimension is 80+0.1, then a lot of parts will be machined at 80.05±0.01

    however, recently i had to deliver some parts, by machining at 0.02doc, and i used cbn inserts, so to obtain a nice surface, even if doc was small

    just saying ... so far i did not worked a lot with such small docs

    i wasn't aware that production is so challenging and for success you need a bit luck and a lot perseverance!
    it is a mix in the mix / kindly

    Ladyhawke - My Delirium https://www.youtube.com/watch?v=X_bFO1SNRZg




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turning low carbon steel : 550M/min 2.6doc f0.35 spindle load 65% ; Genos

turning low carbon steel : 550M/min 2.6doc f0.35 spindle load 65% ; Genos