Hello, I am planning on buying an Elite Foreman machine for my shop in the next couple of months. I am very new to cnc machines, i have mostly been subbing out until now. I am planning on using the machine mostly for plastics and woods, but my shop is a metal shop and would like to use it for soft metals as well.
I saw this spindle on the PWN CNC website labeled as a Metalworking Spindle. The specs/description are “2.2kw 220v ER20 80mm 4-pole 800Hz Water-Cooled Metalworking Spindle” and am wondering if it is worth the extra price ($1300 for a mill/vfd kit). I honestly don’t mind the expense if it allows me to basically have a cnc mill. I’m also curious if it lets you mill steel or if it is just a more efficient spindle for the non-ferrous metals.
usually spindles with 4 magnetic poles run with half speed and double the torque than a spindle with 2 magnetic poles (3000-12000 rpm instead of 6000-24000 rpm) however when this spindle was presented in this forum, it turned out that this was not the case. It just needs 800 Hz instead of 400 Hz but no more torque at lower speed than the average two-pole spindle.
Spindles that have double the torque and half the speed with 4 magnetic poles are e.g. these:
Some VFDs, like the Omron MX2 / Hitachi WJ200, also include support for synchronous (permanent magnet) motor spindles like the DATRON Syncro spindles with which you can mill steel /very/ slowly with high touque, i.e. go down to 1000 or even 100 rpm.
Note that if you intend to mill brass, be aware that dust extraction will not work reliably like it does with wood dust. Unless you use a workpiece cutting or coolant fluid, you should choose a spindle with sealing air because brass dust may ruin your spindle bearings:
Would I be fine with a 2.2kw, 2-pole 400Hz 220v water cooled spindle for brass and aluminum? I think I might get comfortable with the CNC machine a bit before I decide to try and push it too far, lol.
I do think the spindle with sealing air is a smart choice either way though. Do all spindles have a port for this addon or do you need to purchase specific ones?
David in the link above runs the HFS-8022 spindle that I own. too, and a few others in this forum use it, you can choose air sealing as option when ordering one, or let retrofit air sealing by sending it back to the manufacturer. You need compressed air for air sealing. The ATC-8022-HSK25 needs compressed air anyway for the tool change mechanism.
These spindles develop their full torque at speeds as low as 6000 rpm, so they are suited for milling brass and aluminium. It’s only for milling steel that I would choose a spindle with lower speed and higher torque, preferrably a synchronous motor spindle that can go very low at high torque. The spindles we talk of here are asynchronous motor spindles (induction motors).
e.g. 400 Hertz × 2 × 60 seconds / 2 poles = 24,000 rpm
this means with a spindle with two magnetic poles a VFD can deliver 0–24,000 RPM spindle speed if the VFD is able to provide 0–400 Hz. My Omron MX2 can deliver 580 Hz so can run a two-pole spindle with 34,800 rpm.
