Why does it squeal a bit?

[ElderlyGent]

HI all,
The other day I put a new 1/8 upcut end mill into the routyer with a .125 depth of cut and started it going to cut a decorative channel on a box lid, It did the job well, but the bit squealed. Out of cutiosity I tried it again on scrap at slower feed speed and agin with a lesser depth of cut and got the same result. The router speed is around 12k. As those bits are not cheap I would like to keep it if there is a simple nswer to this small problem.
Your suggestions will point me in the riht diretion I am sure, as they have done in the past. Thanks in advance.

Drew.

[Adrian]

The rule of thumb with spiral bits is if they are squealing they are hungry for fresh material. You need to speed the feed rate up, increase the pass depth or slow the RPM's down.

The changes you've made are in the wrong direction to stop the squealing.

Depending on the job it's often hard to get it to stop squealing entirely as tight corners will cut at a different rate to longer, straighter runs.

[ElderlyGent]

Many thanks for the help, I will do as you suggest as soon as I can, Cheers and stay safe.
Drew/

[martin54]

How did you figure out what speed & feed settings to use in the first place?
If you are using chipload calculators, Manufacturers settings or settings you have been given by someone else then these are probably not going to be optimal for your machine because they are general settings & every CNC machine is a bit different.
You really need to use these settings as a starting point & then spend time fine tuning so you get the speed & feed settings right for the CNC machine you are using.
It can take a bit of time especially if you have a lot of different bits but once you have the tool database set up for the bits you have then your bits should last longer & you will know that each job is being machined as efficiently as possible

[logicspeaks]

How many flutes is your bit?

Like others mentioned raise your RPM or increase your feed rate, however I'll add that some bits design do scream more than others.

My 2 flute 1/8 inch compression bit is generally run at 16k rpm at 200-250 feedrate. No screaming, however I find that down-cut or up-cut bits often scream on nearly any setting. Just depends how loud the scream is.

What I would also pay attention to is your waste material. Is it like little c shaped grains of sand or are they powdery. If its powdery thats another sign your feeds and speeds need adjustment (Same idea. powdery = lower RPM or increase feed speed).

[Leo]

One tip I can give is to make sure that you have as much of the shank as possible clamped in the collet as possible - BUT - do NOT have the flutes into the collet. Sticking out too far from the collet face can cause problems.