Feeds and speeds. Some tips for a newbie please!

[Richard]

Is that end mill coated? Looks like it might have tialn coating, which will cause build up pretty quickly, that's probably not erosion but almost certainly a build up of aluminium on the cutting edge. You want uncoated cutters really for ali. And yes find out what the material is, even different batches of the same grade can cut differently but stuff like 1 series ali is horrible for machining.

OK, I'll get a 2 flute uncoated from APT and see how it goes. The cutters I have are coated but I don't know what with.

The part I was machining is the bed of the machine, so no idea what grade it is. I just wanted it flat(er) and level.

Once I get the new 2 flute cutter, is 6k rpm and 500mm/min, dry, still in the right ball park for taking a shallow finishing cut at say 90% engagement?



Just for my own interest, if there is build up on the tips of the cutter, how does that erode the tip?


Thanks for the input!

[Chaz]

OK, I'll get a 2 flute uncoated from APT and see how it goes. The cutters I have are coated but I don't know what with.

The part I was machining is the bed of the machine, so no idea what grade it is. I just wanted it flat(er) and level.

Once I get the new 2 flute cutter, is 6k rpm and 500mm/min, dry, still in the right ball park for taking a shallow finishing cut at say 90% engagement?



Just for my own interest, if there is build up on the tips of the cutter, how does that erode the tip?


Thanks for the input!

What is the highest speed your spindle can rotate at?

[Richard]

What is the highest speed your spindle can rotate at?

Man this thread is getting confusing! LOL!

I don't know how fast it can go. I will have a look at see what it actually tops out at.

It's a Schneider altivar 12 VFC with a water cooled 2kw spindle.

[Dave_stoke]

Man this thread is getting confusing! LOL!

I don't know how fast it can go. I will have a look at see what it actually tops out at.

It's a Schneider altivar 12 VFC with a water cooled 2kw spindle.

Yes sorry richy I somehow derailed and hijacked your thread.

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[Richard]

Man this thread is getting confusing! LOL!

I don't know how fast it can go. I will have a look at see what it actually tops out at.

It's a Schneider altivar 12 VFC with a water cooled 2kw spindle.

I just tried 20k rpm. VFD says 326hz and spindle was going at 19600rpm.


This is what the bed looks like and what the finish was initially and after the tool degraded.

[Snapper]

OK, I'll get a 2 flute uncoated from APT and see how it goes. The cutters I have are coated but I don't know what with.

The part I was machining is the bed of the machine, so no idea what grade it is. I just wanted it flat(er) and level.

Once I get the new 2 flute cutter, is 6k rpm and 500mm/min, dry, still in the right ball park for taking a shallow finishing cut at say 90% engagement?



Just for my own interest, if there is build up on the tips of the cutter, how does that erode the tip?


Thanks for the input!

Noooo. Don't cut the bed.

Get a board, sheet of ali, whatever you want to use and stick it on top. The bed is made of several independent pieces of extrusion and even if you machine it 'flat' they will flex independently anyway. Also you're then tied in to the cutting area, you can't really load a bigger piece in and clamp it outside the work area.

[Richard]

Noooo. Don't cut the bed.

Get a board, sheet of ali, whatever you want to use and stick it on top. The bed is made of several independent pieces of extrusion and even if you machine it 'flat' they will flex independently anyway. Also you're then tied in to the cutting area, you can't really load a bigger piece in and clamp it outside the work area.

Not on my machine. The bed is actually a big thick slab of cast iron, onto which is bolted an ali plate, which is drilled and tapped for tooling. It's basically sacrificial. As this is used machine, the plate had a few cuts in it and after transit and moving ect, it needed leveling.

[Snapper]

Thanks mate, so run the earth into the control box and connect to an earth point there?

Can I use hdmi for the spindle? I have a thicker rca shielded somewhere. I presume most of it is just signal wires?

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No. It's a 3ph motor in there so what you should have currently is just the 3 U V W power wires. I can't remember off the top of my head what the optimal core diameter is for the cable but depending what power spindle you have it isn't hard to figure out the max current and find out on google.

Not on my machine. The bed is actually a big thick slab of cast iron, onto which is bolted an ali plate, which is drilled and tapped for tooling. It's basically sacrificial. As this is used machine, the plate had a few cuts in it and after transit and moving ect, it needed leveling.

Ah, I see. Very nice. Likelihood is it's a cast 5 series aluminium. In which case try drop your RPM by 20%. Have to feed a bit harder in that stuff.

[Dave_stoke]

No. It's a 3ph motor in there so what you should have currently is just the 3 U V W power wires. I can't remember off the top of my head what the optimal core diameter is for the cable but depending what power spindle you have it isn't hard to figure out the max current and find out on google.



Ah, I see. Very nice. Likelihood is it's a cast 5 series aluminium. In which case try drop your RPM by 20%. Have to feed a bit harder in that stuff.

It's 800w the spindle. So I need initially a shielded cable capable of 1500w

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[Snapper]

It's 800w the spindle. So I need initially a shielded cable capable of 1500w

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No, it's 800w @ 220v over 3 phases so, roughly 270 watts per phase or about 1.25 amps. Maybe you could get away with repurposing some sort of signal cable... but I wouldn't personally. Get a proper flexible copper braided cable and do it properly.