Cutting speed

[Marius Gouws]

Good morning
I just want to know from other people that have CNC machines, what their cutting speed is for there 8mm dado cutter. Our machine is setup as follow:(when cutting 16mm Melamine) Spindle speed: 18000(for 8mm downcutter) Feedspeed: 7500(for 8mm downcutter). The thing is, that our 8mm cutter only last for about one day, then it start chipping the Melamine, and our supplier say that it is just us that is complaining about the cutter. So, what am i doing wrong here??
Must I speed up the machine??, slow the spindle speed?? or what. If you look at the cutter, then it is black and blunt only there where it comes in contact with the Melamine.
Any feed back or advise will be welcome.
Thank you very much in advance

[Mark Hesketh]

melamine is absolutely horrible for wearing down the cutters. I use a 1/2\" for most of my melamine operations with a spindle speed of 18000 and feed rate of 750. I rarely get more than about 30 sheets cut before the chipout is bad enough to warrant a tool change. Because of that, I try to always set up my cutting batches to be about 30 sheets, and change the bit between each batch, pretty much once a day. If I am cutting anything other than melamine though, the life of the cutter is much better.

[Geron Stricklin]

We use a 1/2 inch down sprial for all our dado's 18,000 rpm at 400 inchs per minute. We outline with 1/2 inch compression at 18,000 rpm and 400 inchs per minute. We have cut as many as 80 sheets before changing bits.

[Forrest Chapman]

Marius and Mark,

You are burning your bits up. I don't use 1/2\" for much but when I cut with a 3/8\" 2flute comp. on melamine I run 18000rpm at 750 ipm. Try slowing your rpm first to about 15000. I get on average 80 to 100 sheets if I only cut melamine but I did on one occasion get 215 sheets of 3/4\" by 5x8 melamine for one job. The last 15 sheets were laminated 2 sides and did the bit in. On your dado bits you can run 50% faster at the same rpm. Hope this helps.

Forrest

[Rob Davis]

Based on our experience, you are feeding too slowly and bit is getting hot. Nothing dulls it faster than heat. 7500 mm/min is only 300 inches per minute so slow in our opinion. We cut a lot of melamine and it is hard on bits but we feed a 3/8\" compression bit at 650 inches per minute, 18000 rpm and we think that 650 is too slow sometimes. On small little cuts you never get up to that speed anyway. Also make certain you have good dust removal so the bit isn't heating up spinning in dust.
Of all the materials we cut, melamine is the worst on bit life. We use separate bits for plywood and wood. We take dulling melamine bits and switch them to MDF, then out for resharp or discard, depending on the bit.
Just one opinion.

[Marius Gouws]

Thank you all for your response.
It worked! Speeding the 8mm dado cutter from 7500 to 16000 and my 12 mm diamond cutter from 6800 to 8500 and i now get a much better cut.
Now just to see how long they will last. Allmost all our work is cutting Melamine
Thanks

[Michael Kowalczyk]

Marius,
We use a 1/2\" up down shear PCD on 5/8\" MDF core 2 sided melamine all day long at 18500 rpm and 750IPM and get an average of 150-250 sheets per bit. Sheets vary because of the number of parts per sheet. Some may only have 6 parts per sheet and some have 44 parts. we always ramp in which helps preserve the plunge tip.

You should also look into the \"Z\" oscillation part of the controller. I do not have enough straight runs to take full advantage of it but it will allow you to have the bit raise and lower I think an 1/8\" therefore spreading out the the area that the melamine is hitting the bit. Hopefully someone from Thermwood will chime in here to give a better explanation.

Thanks,