how would this spindle work

Personally, I wouldn't even consider it. A spindle like that is better suited to an industrial grade machine.

 

I have machines with 2.2kW+ spindles on, and although having an ER20 collet is very nice, most of the time I use 1/8", 6mm and 8mm shank bits. As Peter says, a bigger spindle is not always the best option, unless you have a very specific requirement of course.

Although a 1/2" bit could be pushed hard with neglible deflection, an 8mm bit pushed as hard as possible on an aluminium frame machine will also deflect very little in practice too. Where having the capacity for a 1/2" shank is useful is for running bits that take inserts, such as some of the larger surfacing bits so that you can skim off a big area quickly, or if a very deep pocket is being cut: I have a cutter that has 150mm of stickout, but you need a lot of Z motion to use it. 1/2" non-insert bits are expensive too.

I notice on the Amazon advert that it is an air cooled spindle. The advert says the speed range is 5k rpm to 24k rpm, which is unusual (but not out of the question) for air cooled spindles, which often have a minimum more like 10k or 12krpm to get enough airflow through for cooling. It would be worth double checking the true minimum speed that can be used. A surfacing bit that takes inserts often has a decent sized diameter (50mm+), and also has to be spun at the lower end of the spindle speed range, really limiting the useful spindle power. The inserts also limit the cut depth, and the large diameter of the bit means that your tramming has to be super accurate in order to prevent tramlines when surfacing an area. The reality is that when you do the feed calculations, the practical material removal rate that can be acheived with a large-diameter slow-spinning tool on that spindle may be lower than spinning say a 25mm diameter surfacing cutter at a much higher speed and cutting deeper. For example, 2-insert 50mm at 5k rpm at 1mm Depth Of Cut and 1500mm/min in oak will be using about 82% of the available spindle power (about 340W needed) and removing 75 cubic cm/min. A 25mm bit at 10krpm has the same surface speed on the cutter, but can be run at 4mm DOC and at the same 1500mm/min feed, still loads the 2.2kW spindle to 82% of what is available (about 680W now needed), but has a 150 cubic cm/min removal rate. A 2mm DOC and 3m/minute feedrate (or ideally 1mm at 6m/min) would give a better chipload, but now needs the machine to push the cutter faster, which eventually will become problematic for an ali-framed machine. The smaller spindles are therefore better power-matched to what material removal rates are actually acheivable when the high rpm's on the spindles are considered.

An ER11 collet will take up to an 8mm shank, and some of the 1.5kW spindles have ER16 collets that can take 10mm shanks, and the spindles are much lighter to move as a heavier 2.2kW will limit the peak acceleration that you can achieve. There are some surfacing bits around with 8mm shanks that take two square inserts to give a 25mm diameter, and are often my go-to for fast skimming of hardwood as in the example above, they can be pushed to give a surprisingly high material removal rate. Evan

 

There are a number of factors that need to be balanced to work out which type may be the best for you. Water cooled run quieter than air cooled, often have a wider useable rpm span, but they need a pump and 'plumbing'.

The noise issue may well be offset by how loud any vacuum system is though, and with many cutting operations, the cutting process itself will be much louder than a water cooled spindle. I find heavy cutting such as slotting sheets or roughing is loud and I need earmuffs, but with 3D finishing, I usually have the vac off and the steppers are often louder than the cutting or water cooled spindle.

Air cooled usually pull air downwards through the spindle, blowing down onto the work piece. The downwards airflow may aid in clearing chippings for some machines, but could also interfere with some dust collection systems. A water cooled spindle does not have any additional airflow, so you can control how chippings are removed more easily using other air-jets and vac systems.

The coolant setup for a water cooled system is not difficult in practice and a lidded bucket with a few gallons in it will often have enough surface area to dissipate the waste heat, certainly for the smaller spindles. My large machine has a 3kW spindle and a small 3 litre reservoir, but the out-flow pipe back into the bucket goes through a cheap radiator with three 120mm fans attached that is designed for cooling a desktop PC, which is enough to keep it cool. If the cooling pipes are run through an existing drag-chain, it would need to be checked to see if it is getting packed a bit too tight.

Much really comes down to price and availability otherwise (and the collet size), and as Peter noted, if it is sold as a bundle, go for one that has a decent VFD.

 

I have a 1.5kw air cooled spindle. I use it only on wood. I didn't have the need, so far, to do aluminum. I found it to be way bigger than I really need. If I had to do it again, I'll buy a 800w spindle, like Peter mentioned above.
For flattening surfaces I use a 8mm shank 1", 3 inserts, bit. It does it with no hiccups and the smaller spindle would not complain either, I'm sure.
As for noise, my vacuum is WAY louder than anything else. Without the vacuum I could cut with no ear protection but I need it with the vacuum.

 

I use a RoutER11 for everything from soft plastic to mild steel, including quite a lot of work with aluminium. Shifting the extra weight of a large water cooled spindle around is probably going to have quite an effect on your acceleration. Unless you are doing long straight cuts you may not get any overall advantage in terms of reducing job times and certainly won't be using all the power available. Larger collets are only really an advantage while you have a stock of bits that fit them - almost all the bits you are likely to need are available with smaller (6mm or 1/4") shanks.

Alex.