Cutting Speed Table

[OuBallieParticipant @ouballie]

Andrew,

Agree.

My post was a little tongue in cheek, hence the horns

I still do, however, use sight and sound BUT making sure the tool bit is both sharp and cutting, not just scraping.

I'm still experimenting with the Feed and cut using the tangential, but haven't yet got to Neil's level of blue chips flying off.

Neil,

It took using the tipped parting tool to come to the same conclusion, with parting now a pleasurable experience, whereas previously it was a nightmare.

How did you manage to get those chips flying off blued?

Geoff – Time to finish the FeedRodMotor

[richard 2Participant @richard2]

From a 60mm sq block of ali I have to remove a piece 19mm wide by 40mm deep.

I have a good selection of endmills from 3mm – 20mm.

1) What would be the best size cutter for the job?

2) What would be a suitable speed to run the cutter at?

3) What should be the depth of cut?

The mill is a Warco WS16

and I have a Super 7B with vertical slide, etc..

Sorry these are all "kiddie" questions but I am a musician not an engineer.

I would much appreciate some help on this before I ruin anything.

Regards and thanks to all.

Richard.

[SillyOldDufferModerator @sillyoldduffer]

I'll be interested to hear what the experts say. On the WS16 I would go for:

1. 20mm cutter
2. 10000 / 20mm = 500 rpm
3. 15% of 20mm, = 3mm
4. Splash plenty of Paraffin, WD40 or cutting fluid as lubricant.

Dave

[richard 2Participant @richard2]

Thanks, Dave,

You're a gem.

Richard.

[duncan webster 1Participant @duncanwebster1]

I'd start with a hacksaw, but then I don't mind sawing if there is something good on the wireless

[Henry ArtistParticipant @henryartist43508]

Using a lathe or a milling machine is a bit like making love. Best results are obtained if you pay attention to the feedback.

[David Standing 1Participant @davidstanding1]

Posted by Henry Artist on 24/04/2017 08:59:27:

Using a lathe or a milling machine is a bit like making love. Best results are obtained if you pay attention to the feedback.

And if your windings start smoking, you probably need to back off the feed rate .

[Martin ConnellyParticipant @martinconnelly55370]

Richard 2

To use the table that started this thread your cutter is Ø20mm and the material is aluminium. This gives a speed from the Ø19 line of 1006rpm. Consider this a maximum speed if you have a machine with enough power at this speed and choose something close to it eg 1000rpm would be fine but lower would also work.

What this table does not tell you is feed rate for milling. It is important to keep the cutter cutting not rubbing as earlier posts have stated. If we take the rpm to be 1000 for ease of calculation then we need to look at tooth load and number of flutes on a cutter. Let's go for a tooth load of 0.125mm or 0.005". First we can consider two flutes, this will give a count of 2×1000 = 2000 teeth per minute at the cutting point. In order to give a tooth load of 0.125mm we need to multiply the teeth per minute by the tooth load and we get 2000×0.125 = 250mm/minute as the feed rate. If we put the figures in for 4 flutes we get 500mm/minute as the feed rate.

So if you want to cut at the correct tooth load with a Ø20 milling cutter with 4 flutes you need to feed the material past the cutter at 500 mm per minute or 20" per minute.

Can you achieve this? It will depend on your choice of hand cranking, power feed or CNC on you machine. If you are hand cranking I think you should time yourself over a suitable distance to get an idea of the speed you need to go. Similarly if using a power feed you should find what speeds you get for the available settings. Using smaller cutters with higher rpm will require even faster feed rates.

One other thing about cutting aluminium is the risk of aluminium welding itself to the cutter resulting in built up edge. **LINK** This is why some lubrication is necessary and avoiding excess heat from rubbing helps.

Martin C

[Martin ConnellyParticipant @martinconnelly55370]

Richard 2

You may have no intention of getting into CNC at any point but it may be worth downloading Mach3 onto a computer. This has a wizard for speeds and feeds for milling included in it. It can be run in demo mode without a license (just select no device when asked when it runs) but the wizard works fine. Just make sure you have selected the correct units (mm or inches) in the config settings and close the program to set the units then start it up again.

Martin C

[Richard –Participant @richard-3]

Out of interest a similar exercise as Martin using the free speed and feed calculator as provided by Little Workshop

Might help
Richard

[colin hawesParticipant @colinhawes85982]

The cutting speeds can be wildly different to the theoretical but generally the speed can be set by what the tool temperature and the machine can withstand; the feed rate can be increased with speed up to that limitation, for example, we often use far to slow a speed to cut screw threads because we can't handle the feed rate. The same applies to facing large discs where we need to consider the largest diameter although the speed is really too slow at the smallest diameter when you have no facility to continuously change the speed. By "feel" you can increase the feed rate as the surface speed increases. Colin

[Perko7Participant @perko7]

"From a 60mm sq block of ali I have to remove a piece 19mm wide by 40mm deep."

I'd start with a bandsaw and clean up in the mill. Would be a lot faster, and you'd end up with a nice useable spare piece of ali rather than a bigger pile of swarf.

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