LR3 bad cutting after one successful part

Hi, My LR3 has been reliable and always cut first time right and proper. Never had any issues. Ive cut max 12mm ply or MDF. However this latest project is 18mm ply and after cutting the first near identical 2 of 4 parts it is struggling with the 3rd and 4th. Heres my setup :
1/4 sheet size LR3 (2 or 3 years old)
arduino mega Ramps 1.4
Makita RTo702cx

For this job Im using a 6mm 4 fluted flat end mill bit, never had an issue with them before and its brand new.
The cut was set up in Fusion 360, 88 m/min at 1.5mm depth per cut.
It doesnt seem to be struggling with the first 2-3 mm only as it gets deeper.

Am I driving this too fast and have just gotten away with it for so long and should I turn the feed rate way down ?

Thanks for any advice. Regards
Jim

Sorry to hear it’s struggling. Can you elaborate a precisely what its doing? Or upload a video?

What speed setting do you use on the router? Does it sound like its bogging down?

4 flutes is a lot, but its tough to know if its contributing to the problem. Are you drilling? What is your Z-feedrate? Is it a typo and 88mm/min or 1.47 mm/sec? 1.5 mm depth per cut is pretty shallow, so I’d guess that’s fine. But is it scorching the wood? Are there sounds like squealing when it’s struggling? Does it start losing steps?

I think a bit more information may help narrow the problem down. Lots of great minds here have helped me solve problems. Hopefully you’ll generate a lot of suggestions to solve it and get your project cut.

If your dust collection is bad you are recutting the dust, which basically doubles your DOC and heats up the endmill.

Hi all, thanks for the replies but I seemed to have solved the problem by changing the bit for a straight 2 flute flat end grooving bit. After all a simple 6mm groove was all it was doing although cutting out 18mm parts. It seemed to cut very smoothly and less noisy. I think it was the wrong choice of bit and the first two were lucky with the 4 fluted flat end mill bit.

For reference, while I own some 2 fluted bits, I use single flute for most of my work. Even then I find I have to turn down the spindle speed to get chips rather than dust.