Milling machine feed rate

[petro1headParticipant @petro1head]

I know the formula is:

Vr = Fz x z x n

Fz – Feed per tooth

Z = Number of teeth

N = Speed RPM

I am using a 10 mm 3 tooth HSS-AL TiAlN Coated End Mill from ARC

For mild steel the spindle speed will be 1000rpm

However how do I find the Feed per tooth (Fz)?

Edited By petro1head on 10/09/2023 09:55:19

[petro1headParticipant @petro1head]

[petro1headParticipant @petro1head]

I have found this YouTube vid which I thinks helps

HERE

 

 

Edited By petro1head on 10/09/2023 10:17:09

[JasonBModerator @jasonb]

That is a variable that often depends on the type of cut and how much of the cutting edges are being used.

If cutting a slot where the whole width of the cutter is being used then you would probably want a lower Fz than if using the side of the cutter to profile an edge.

Some makers give optimum Fz figures for their cutters so you may find for a slot of 0.5D depth the Fz is 0.027mm but for side cutting at 1.5D height and 0.1D stepover the Fz would be 0.045mm on low carbon steel (YG-1 figures for similar spec cutter)

You will need to adjust it to suit a hobby machine, start with say half that and see how the cut sounds and what the chips look like

 

Edited By JasonB on 10/09/2023 10:20:57

[petro1headParticipant @petro1head]

Posted by JasonB on 10/09/2023 10:19:51:

That is a variable that often depends on the type of cut and how much of the cutting edges are being used.

If cutting a slot where the whole width of the cutter is being used then you would probably want a lower Fz than if using the side of the cutter to profile an edge.

Some makers give optimum Fz figures for their cutters so you may find for a slot of 0.5D depth the Fz is 0.027mm but for side cutting at 1.5D height and 0.1D stepover the Fz would be 0.045mm on low carbon steel (YG-1 figures for similar spec cutter)

You will need to adjust it to suit a hobby machine, start with say half that and see how the cut sounds and what the chips look like

 

Edited By JasonB on 10/09/2023 10:20:57

Cheers Jason, so out of interest what do u do to calc feed rate

 

Edited By petro1head on 10/09/2023 10:22:40

[JasonBModerator @jasonb]

Fz x flute x rpm

0.027 x 3 x 1000 = 81mm/min for the slot (YG give 1100rpm)

0.045 x 3 x 1000 = 135mm/min for the side cut (GY give 1100rpm)

Generally on the manual machine I've just go a feel for the speed and how fast to turn the handle and generally adjust how fast I'm turning if it does not sound right.

On the CNC I've got used to what works with the cutters I typically use and may just alter the feed if needed when doing the CAM, if it's a finish cut I'll probably slow it down a bit same if very deep or lots of tight internal corners to reduce the risk of chatter.

[petro1headParticipant @petro1head]

Posted by JasonB on 10/09/2023 10:30:02:

Fz x flute x rpm

0.027 x 3 x 1000 = 81mm/min for the slot (YG give 1100rpm)

0.045 x 3 x 1000 = 135mm/min for the side cut (GY give 1100rpm)

Generally on the manual machine I've just go a feel for the speed and how fast to turn the handle and generally adjust how fast I'm turning if it does not sound right.

On the CNC I've got used to what works with the cutters I typically use and may just alter the feed if needed when doing the CAM, if it's a finish cut I'll probably slow it down a bit same if very deep or lots of tight internal corners to reduce the risk of chatter.

Thanks

[duncan webster 1Participant @duncanwebster1]

I use this from Presto to get tooth load, but I then run rpm slower as i don't have flood cooling and I want the cutters to last a bit longer. Running with too low a tooth load results in blunt cutters as they rub instead of cut

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