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IndustryArena Forum > CNC Electronics > Spindles / VFD > Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill
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  1. #1

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    Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill

    Hello,

    I'm having a little trouble setting correct settings (I'm new in this) for mill aluminium 6063-T5 on a RTM-80-2.2 (https://www.aliexpress.com/item/32880152613.html) spindle. Calculator gives crazy feeds and i'm not sure to trust them.
    The only sucessfull mill was using a 3.175mm 2 flute at 5000RPM and 150mm/m feed, then i boost to 200 and even 250mm/m without break the tool.
    Now i want use a HSS 8mm 2F bit for a big pocket and i like to ask first before use it and ruin something. For example calculator gives 6310RPM at 1413.52mm/m for a DOC of 1mm and 8mm pocket.
    After reading about these spindles i notice they are not good at low RPMs, some websites say 6000, people says 4000/6000/8000 and i ask the seller which told 9000 as minimum. Also i ask for power curve but none have such data... So with that high variance of RPMs min, what should i take? The seller recommendation?
    Also does my previous cut at 5000RPM can wear spindle or damage it if i continue use such RPMs?

    Heres a picture of my first sucessfull mill on Alu:



    PS: My machine is a 9060 homemade all made of steel and linear guides

  2. #2
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    Re: Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill

    Have you tried finding data for high speed machining?You have a router spindle and it won't be too happy at low rpm,not to mention developing only a fraction of it's power.You may have to adjust your cutting preferences for a lighter cut depth and more passes.If machining metal is going to be your main activity, a mill might be a better choice.One other factor might be the height of your gantry beam-simple leverage means that a high gantry and it's attendant big Z axis travel will permit more chatter than a lower setup.

  3. #3

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    Re: Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill

    Quote Originally Posted by routalot View Post
    Have you tried finding data for high speed machining?You have a router spindle and it won't be too happy at low rpm,not to mention developing only a fraction of it's power.You may have to adjust your cutting preferences for a lighter cut depth and more passes.If machining metal is going to be your main activity, a mill might be a better choice.One other factor might be the height of your gantry beam-simple leverage means that a high gantry and it's attendant big Z axis travel will permit more chatter than a lower setup.
    I mainly cut wood but like the hability to do some works on aluminium, simple stuff.

    For HSM i found this: https://makeitfrommetal.com/cutting-...bbyists-guide/
    The good is the fact he use same kind of machine and spindle, have to test the results, still he work with low DOCs which is expected.
    My Z axis is definitely big and i still need to put the machine on a firm base to eliminate the vibration.

    I also found a good datasheet that match my spindle: http://dbsrrwqxc6ai9.cloudfront.net/...-ER20-220V.pdf
    It have some more information but still lacks of a torque graph. If minimum is 6000RPM and seller told me 9000 can i assume that 9000RPM is torque max peak?

    After search on aliexpress i also found slower spindles which look better for metal, and reach 1500-12000rpm can it be a good balance between wood and aluminium?
    https://www.aliexpress.com/item/32996693858.html and https://www.aliexpress.com/item/32546317403.html

    EDIT: Found torque graph in description GDK85-12Z/2.2, but it show 3KW instead of 2.2?


    EDIT2: Found datasheet for GDK80-12Z/2.2 http://www.pdjinc.com/GDK80-12Z_2_2_manual.pdf It have torque graph on bottom

  4. #4
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    Re: Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill

    The obvious first step is to try a job with the alternative cutting parameters you found.The large Z axis travel will still allow a bit more movement than a lower amount of travel as the amount of play in the bearings is magnified by the distance from the rails and then you have the same large amount of potential movement at the bottom of the Z axis travel again because of the distance from the gantry beam.Finally,are you absolutely certain that the clamping arrangements for you spindle are completely free from flexing?Switching to a slower spindle won't eliminate any juddering from having the play inherent in the rails present.Have you tried placing a dial gauge against the collet nut and flexing the nose of the spindle sideways in the X and Y directions?

  5. #5
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    Hello!

    First of all: forget HSS tools for machining metals. Use carbide tools, for a 8mm endmill (z=2..3) you should use about 10-12000 rpm at minimum (around 300m/min Vc, most carbide mills requires it on aluminium), with your routing machine use hsm toolpath with 8mm cut depth and 0.4mm cut width with about 1200-1400mm/min feedrate. For plunge use spiral toolpath with 2-3 degrees plunge, with about 450-500mm/min feedrate. Hope this will help!


    Quote Originally Posted by sn4k3 View Post
    Hello,

    I'm having a little trouble setting correct settings (I'm new in this) for mill aluminium 6063-T5 on a RTM-80-2.2 (https://www.aliexpress.com/item/32880152613.html) spindle. Calculator gives crazy feeds and i'm not sure to trust them.
    The only sucessfull mill was using a 3.175mm 2 flute at 5000RPM and 150mm/m feed, then i boost to 200 and even 250mm/m without break the tool.
    Now i want use a HSS 8mm 2F bit for a big pocket and i like to ask first before use it and ruin something. For example calculator gives 6310RPM at 1413.52mm/m for a DOC of 1mm and 8mm pocket.
    After reading about these spindles i notice they are not good at low RPMs, some websites say 6000, people says 4000/6000/8000 and i ask the seller which told 9000 as minimum. Also i ask for power curve but none have such data... So with that high variance of RPMs min, what should i take? The seller recommendation?
    Also does my previous cut at 5000RPM can wear spindle or damage it if i continue use such RPMs?

    Heres a picture of my first sucessfull mill on Alu:



    PS: My machine is a 9060 homemade all made of steel and linear guides

  6. #6

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    Re: Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill

    Quote Originally Posted by routalot View Post
    The obvious first step is to try a job with the alternative cutting parameters you found.The large Z axis travel will still allow a bit more movement than a lower amount of travel as the amount of play in the bearings is magnified by the distance from the rails and then you have the same large amount of potential movement at the bottom of the Z axis travel again because of the distance from the gantry beam.Finally,are you absolutely certain that the clamping arrangements for you spindle are completely free from flexing?Switching to a slower spindle won't eliminate any juddering from having the play inherent in the rails present.Have you tried placing a dial gauge against the collet nut and flexing the nose of the spindle sideways in the X and Y directions?
    Will have a look at it tomorrow, thank you for pointing out.
    I have photos of the machine on thingyverse, but website is now bad and doesn't show all photos i posted.
    https://www.thingiverse.com/thing:3819149
    https://www.thingiverse.com/thing:3849307

    Quote Originally Posted by tnorbi90 View Post
    Hello!

    First of all: forget HSS tools for machining metals. Use carbide tools, for a 8mm endmill (z=2..3) you should use about 10-12000 rpm at minimum (around 300m/min Vc, most carbide mills requires it on aluminium), with your routing machine use hsm toolpath with 8mm cut depth and 0.4mm cut width with about 1200-1400mm/min feedrate. For plunge use spiral toolpath with 2-3 degrees plunge, with about 450-500mm/min feedrate. Hope this will help!
    I know HSS not the ideal for metal, but is that bad with aluminium? Right now i have Carbides but they are TiAIN coated and i guess that not good with aluminium? But i have TiCN bits on the way.
    "at minimum (around 300m/min)" -- If run slower will it hurt the bit? for Example 200mm/m?
    "8mm cut depth and 0.4mm cut width" -- I guess they are reversed? You mean 0.4mm cut depth (DOC) and 8mm cut width (Pocket)?

    For the first slot i'm using adaptive toolpath with spiral plunge, 16mm slot
    Second slot (width = bit diameter = 8mm) The plunge is made in a zig-zag pattern, should i take a smaller bit and use same strategy above?



    Thank you for sharing the parameters, will test them latter.

  7. #7
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    Re: Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill

    I followed the links to the thingiverse pages.You seem to have a good deal of experience with 3D printing and some very good machine accessories are there.One thing that stood out was the side plates of the gantry-they look a bit thing for resisting flex as the spindle moves across the gantry.Maybe bolting a piece of 40mmX40mmX5mm angle to the sides would reduce any tendency to flex.

    For cutting strategy,it may be best to machine slightly oversize and then to run a light finishing cut as long as you are able to securely hold the parts in place.Maybe cut the holes first and then use bolts through those holes to hold the parts while you machine the outer surface.It definitely looks like a machine for HSM strategies rather than milling in a conventional sense.Coolant might also be a good thing to use but things do get messy.Which is why machining centres are enclosed and flood the cutting zone with coolant.

  8. #8

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    Re: Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill

    Quote Originally Posted by routalot View Post
    One thing that stood out was the side plates of the gantry-they look a bit thing for resisting flex as the spindle moves across the gantry.Maybe bolting a piece of 40mmX40mmX5mm angle to the sides would reduce any tendency to flex.
    You mean a L Shape 90 Degree bracket? something like that: or https://www.aliexpress.com/item/32887666132.html

    Quote Originally Posted by routalot View Post
    For cutting strategy,it may be best to machine slightly oversize and then to run a light finishing cut as long as you are able to securely hold the parts in place.
    You mean slightly undersize instead? Example: Slot is 8mm width, so use a inferior bit diameter than 8mm?

    Quote Originally Posted by routalot View Post
    Maybe cut the holes first and then use bolts through those holes to hold the parts while you machine the outer surface.It definitely looks like a machine for HSM strategies rather than milling in a conventional sense.Coolant might also be a good thing to use but things do get messy.Which is why machining centres are enclosed and flood the cutting zone with coolant.
    My stock have space to do that is a 250mm bar and i will use only +/-200 of it. Still my 3d printed holders already do the job, securing the parts.
    As coolant i use WD40 and also have another brand that cooldown the part at same time, it contain some sort of freezer. But i'm never sure what frequency i should spray, the way i'm doing it i think a can will not last long. The machine have oil support but as i have a wood wasteboard removing it everytime is a bit of pain and the wasteboard is planned, without it Z can have 6mm variance across bed point to point. Also it's not high pressure, just a regular flow compared with the water cooling on spindle in terms of flow

    I also have took better photos of the machine:










    Thanks for your input

  9. #9
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    Re: Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill

    The additional images are helpful.The sort of angle section I would recommend would be something like this https://www.monarchmetal.com/wp-cont...tock-angle.jpg and I would put it on the side plate of the gantry with the long edge running from bottom to top.There is no such thing as a machine that is too stiff.

    When I describe machining oversize it means leaving additional material for a finishing pass and inside a slot that would leave the slot narrow because there would be material still to be removed.For the slot I might try using a 6mm tool.

    You have the first machine I have seen with heat sinks on the steppers-interesting idea.

  10. #10

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    Re: Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill

    Quote Originally Posted by routalot View Post
    The additional images are helpful.The sort of angle section I would recommend would be something like this https://www.monarchmetal.com/wp-cont...tock-angle.jpg and I would put it on the side plate of the gantry with the long edge running from bottom to top.There is no such thing as a machine that is too stiff.
    Placement like that on the back: ?


    Do you know any online store that sell that kind of angle stuff inside Europe?

    Quote Originally Posted by routalot View Post
    When I describe machining oversize it means leaving additional material for a finishing pass and inside a slot that would leave the slot narrow because there would be material still to be removed.For the slot I might try using a 6mm tool.
    Got it

    Quote Originally Posted by routalot View Post
    You have the first machine I have seen with heat sinks on the steppers-interesting idea.
    Yes it come without them, but steppers get really hot after a while, to the point i can touch for more than 1s. And i don't like it. So i order and placed that heatsinks, look good and really do the difference. I also thought in put dedicated WC block on them, but it would add extra complexity and tubes. Think is good with passives

  11. #11
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    Re: Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill

    That is exactly the principle I am advocating.I am visualising pieces of that type fixed vertically on the end plates of the gantry and I would think steel would be a good choice.Maybe I am fortunate in having a business that sells all sorts of useful steel just a few minutes drive away,I can't imagine it would be particularly inexpensive to buy online as the freight cost might be significant.You might find pieces of storage rack or bench legs in a junkyard for very little money if you are willing to compromise on size and perhaps clean it.

    Have you tried pushing the spindle nose to measure the deflection?I suspect you would help the spindle rigidity if you used the 3D printer to make an additional clamp for the spindle to be located near the top of the body.It shouldn't see forces of the same level as the metal clamp you already have and has to help minimise juddering at the tool.

  12. #12

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    Re: Chinese 2.2kw 24000rpm Spindle minimum RPM and aluminium mill

    Quote Originally Posted by routalot View Post
    That is exactly the principle I am advocating.I am visualising pieces of that type fixed vertically on the end plates of the gantry and I would think steel would be a good choice.Maybe I am fortunate in having a business that sells all sorts of useful steel just a few minutes drive away,I can't imagine it would be particularly inexpensive to buy online as the freight cost might be significant.You might find pieces of storage rack or bench legs in a junkyard for very little money if you are willing to compromise on size and perhaps clean it.
    You are lucky, here is hard to find any kind of bussiness selling that parts, even rustly or junk. It's easier to find plain bars but L shapes.... But may be my fault as i live in a village and not much aware what exists on near-by cities. When i ask people they also don't know because its rare to find someone attach to this area or wordsmith. That's why i ask for online store, a click away to buy.

    Quote Originally Posted by routalot View Post
    Have you tried pushing the spindle nose to measure the deflection?I suspect you would help the spindle rigidity if you used the 3D printer to make an additional clamp for the spindle to be located near the top of the body.It shouldn't see forces of the same level as the metal clamp you already have and has to help minimise juddering at the tool.
    Tried just now, but i have grabed spindle with two hands instead of nozzle, is that ok? So i got 0.20mm difference and 0.30mm max

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