[daniellyall]

I have been offered a job cutting wing struts out of aluminium I have a large cnc router with out coolant. what is the max depth people think I can cut and what speed do people think will be ok to use with out coolant.
i know coolant will be best to use. i don't know at this stage how much work I will be doing, so not going to invest in setting up coolant pump and gutters on machine unless its $1000`s of dollars of work

any suggestions will betaken on board

[neilw20]

Get a few scraps and try to do cuts to ensure you are able to machine to the tolerances demanded.
You might make expensive scrap.

[Jason3]

I agree with Neil - best thing would be to give it a try.

The fewer flutes on the cutter, the better. Make sure you keep the chip load up. As you go deeper, getting the chips out becomes more important. A spray of CRC will help avoid gumming up the cutter. Max. depth per pass will likely be limited by the spindle power and machine rigidity. Max overall depth will probably be limited by the need to clear the chips.

Speed would depend on the cutter. If you're using a single flute 1/4" cutter then a good start would be 0.10 mm chipload, and full speed on the spindle.

What alloy is the material?

Regards,

Jason

[daniellyall]

the machine is pretty solid it has a 3 HP water cooled spindle so motor grunt is not a problem.
don't know what alloy.
it was from talking to next door, he and some mates are going to be rebuilding a old war bird

[underthetire]

Got air? A air tool oiler, some olive oil, and a very small nozzle will do wonders. Only need a drop every 5 seconds or so.

[daniellyall]

the aluminium I will be cutting will be 6061.
will mount a air jet close to cutter to blow chips out as its cutting I mite put a venturi valve on the air line close to machine so it gets some lube what do people think the best lube to use will be.
also what is a good charge rate it will be gussets and spars I will cutting out for a home build plane, plus charge rate for doing the drawings for them

[mdonovan]

Got air? A air tool oiler, some olive oil, and a very small nozzle will do wonders. Only need a drop every 5 seconds or so.

just my thinking. throw lots of air focused right at the tool tip. keep those chips blowing away. and take a cutting pass then take a break and let things cool down.

they don't call it "coolant" for nothing! if you don't have liquid to carry away the heat, then air flow and cool off time will do instead!

the little bit of olive oil will help too, but more important let the air flow as much as you compressor can handle.

[aarggh]

I haven't tried the olive oil myself, does it adequately lubricate without "gumming" up?

cheers,
Ian

[Coxsteve]

I can't see something as light as olive oil gumming up when cutting Aluminium,after all when porting cylinder heads using the appropriate coarse cutters we simply touch the carbide cutter on a candle to stop the same issue of loading up of alloy on the cutter from occuring so if a smear of candle wax works a treat, olive oil should do unless it flys off too easily from the Cutter.
The cooling aspect is another thing altogether as air is not the best coolant approach when compared to flooding the work as per normal.You can also experiment with appropriate coolant applied with a pressurised spray bottle manually or rig a feed line from such a pressurised bottle with a simple adaption of regulated shop air for a jury rigged coolant system to keep such a bottle pressurised.
Just need to keep on top of the coolant supply itself with such an approach but it can be done quickly and cheaply to see if coolant system is a must have option.

[Geof]

Worrying about cooling is not necessary. When cutting sheet or thin plate the bulk material acts as a large heatsink for any heat generated in the cut.

A misting system using one of the cutting fluids designed for misters would work fine. Brushing cutting fluid along the line of the intended cut would work fine. That is brush it on before starting the machine. Brushing regular automobile automatic transmission fluid along the cut line would also work fine.

Use a cutter with a good helix to help screw the chips out of the cut and a feed of about 1 - 2% of the cutter diameter per tooth.

[daniellyall]

will be making my own mister have enough bits and pieces lying around that will cost $0 to make just mite have to get a nozzle

does anyone have a good idea for make a mister

[warrenb]

Here is what I have done with good results... Since it is not a production job...

2 flute solid carbide standard helix cutter, .02" deep cuts (angled plunge) at 10,000 RPM at about 50 IPM with a "Kool Mist" misting system. If you are cutting a contour make sure to do a stepover of about .100" so your chips can clear when the slot is getting deep and router heads aren't very square to the table to make a deep slot cut.

Do not underestimate the clamping system.

Sure you can push it a lot harder then what I have suggested by why push it. One thing to do is make sure to measure the runout on your tool and compensate accordingly. Alternatively when you are testing run a straight slot and measure the actual cutting width you're getting from your cutter.

Good luck and post pictures for us.

Edit to add...

For your charge, take your usual shop rate and your time estimate and double it. You'll probably break even that way. But be fair and if you come out ahead make sure to refund some back to the customer. Aircraft parts are tricky sometimes.

[daniellyall]

finely be told what grade and size the material is its 2023 t3 1.6mm thick.
just one question for all you good blocks who have posted to this are measurements you put in for cutting are they in imperial or metric my guess is imperial in NZ we use metric mainly ant way thanks to all that have posted