High-pitched squealing when cutting ash wood – CNC

General Chat
1

I’m using an Avid CNC Pro (NEMA 34) with a 3 kW spindle to cut solid ash. Tool • 8 mm solid carbide spiral upcut end mill • 2 flutes • 45 mm flute length • ER20 collet Current settings • 16,000 RPM • 6,400 mm/min feed • 0.20 mm/tooth chip load • 2.5 mm stepdown • Ramp feed: 3,000 mm/min • Plunge: 2,000 mm/min • 2° ramp • Dust extraction ON I’m cutting circular contours/full-width 8 mm slots in 20–35 mm thick ash. The cut looks clean with no burning, but I get a noticeable high-pitched squealing/chatter sound that changes depending on the position around the circle. Helical holes with the same tool cut perfectly. I have also tried 4,000 mm/min feed and 1–1.5 mm stepdowns, but the squealing remains. What would you recommend? Is the 8 mm × 45 mm tool too long/flexible? Would a shorter Ø8 or a Ø10/12 be better? Could full-width slotting be causing the noise? What RPM, feed, stepdown and cutting strategy would you use for ash?

Thank you.

2

If you “air cut” the same cut, does it make the sound? I.e. is it the steppers/servos making their PWM hum?

(yes, the hum might be different under load)

3

Probably vibrating the long bit, making the screaming sound. Less stickout or a thicker bit would definitely help.

4

I would point the noise towards the full width slot cutting. Try reducing the feed rate by 50 to 75 % and see how it sounds.

5

Counter-intuitively, also try increasing the feed rate too. router bits typically want a bigger bite than we give them.

Last time I had a screetching bit, I ended up slowing down the RPM and increasing the feed until it was happy.

6

El sonido es a la hora de cortar cuando la fresa penetra en la madera y empieza la trallectoria de corte, estoy enque puede ser bajar RPM y usar fresas lo mas cortas posibles o mas gruesa para contornos circulares en fresno, pero de momento no se. También estoy haciendo profundidades de 2-3 mm en una fresa de 8 para ser conservador, podría ser mejor subir a 4 mm? para que la fresa sea mas estable, de momento voy a modificar bajar RPM 12000, avance 4800 mm/m y profundidad 4 mm, cortando en sentido horario en el contorno exterior a ver como va. Gracias.