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View Full Version : Solid Carbon Fiber - Composite Cutting Advice needed.



dachopper
16-07-2017, 01:34 PM
Hi guys,

After completing many mods and altering feeds and speeds on my machine to get more reliability.... my first attempt at cutting Carbon fiber has resulted in Y axis stall detect errors.

I just wanted somebody to double check my calculations to make sure my feeds and speeds are in the ballpark

I used the Aman tool 48054B in 1/4 inch size for the purpose of slot clearing, and later 3d Profiling relatively flat profiles.

I counted the number of cutting edges, and input 9 flutes for the calculation, running my watercooled router at full speed ( 24,000 rpm ), to try and get the motors running fast enough for stall detect to operate.

Feed rate was set around 2400 mm/min, and depth of cut for the slot 2mm. There were no Z or X axis movement when the stall occurred, the motors were just in the middle of pushing the bit up the piece.
The manufacturer speeds advertised are
1,600 - 3,200 SFM, and chipload .0024 - .004".... IPR converted to metric chipload & rpmbelow

.0635mm to .1016mm per revolution. At 24,000 rpm. 24,000 x .0635=1524.... or 24,000 x .1016 = 2439 mm/min

Dam, just noticed the operating RPM says 18,000. 18,000x.1016 = 1828, well that explains that then ! FFS

Anyone recommend any other bits for carbon roughing?

Ger21
16-07-2017, 02:35 PM
I'd send an email to Amana and ask them for clarification?
I don't understand how to use the info for that tool.

https://www.amanatool.com/pub/media/custom/upload/File-1445372390.pdf

The chart says SFM of 1600-3200. If you use 2000 with their formula to find rpm, I get 30,000.
And if I look at the pic of the tool bottom, I count 16 flutes.
https://www.amanatool.com/48054-b-high-performance-solid-carbide-fiberglass-and-composite-cutting-1-4-dia-x-2-1-8-x-1-4-shank-altin-coated-burr-end-router-bit.html#feed_rate.tab

If you use 16 flutes in the feedrate calculation, I get 860ipm at 18,000 rpm, which is clearly wrong. Even using 9 flutes would give too high of a number.

dachopper
18-07-2017, 08:20 AM
Thanks Ger,

I ignored the calculations at the bottom, because it kind of appears, that they have all ready done the calculations for you...

Ie - they stated an operating RPM of 18,000, they know the diameter and flute number, and they stated a feedrate per revolution, rather than chipload per tooth. so just using the RPM + Inch per Revolution I can see the recommended feed rate range straight away,and you are correct this does not correlate with the " calculated" number if you assume each burr is equivalent to a cutting flute.

I have to wait for some new tools to arrive in the meantime.... I might give them an e-mail.

Nick

Dean jeffery
18-07-2017, 08:37 AM
I use the corn cutters from eBay (china) cost around 50p each for 2mm cutters.

Speed 24k feed 900 DOT .6 to 1mm profiling

Bin the cutters after 25mins use

Clive S
18-07-2017, 09:09 AM
I have to wait for some new tools to arrive in the meantime.... I might give them an e-mail.


Does this chart help: https://www.toolstoday.com/pdf/HP-Fiberglass-Composite-Cutting-Speed-Chart.pdf

magicniner
18-07-2017, 01:54 PM
I counted the number of cutting edges, and input 9 flutes for the calculation

There's your FUBAR, single flute works very well for CF Composite, there is no such thing as "Solid Carbon Fibre" BTW, just fibre size and density of composite ;-)

- Nick

dachopper
18-07-2017, 09:21 PM
Thanks for the advice, tool manufacturer said the slow speed is down to heat, if there is too much heat build up then instead of cutting the flute clogs, putting extra pressure on the axis motors as the fluted are no longer cutting, then stall detect turns motors off.. So lower rpm , 7-10,000 rpm can keep tool cooler, and avoid resin melting if that's the problem.basically he said its entirety dependent on the exact property of the carbon resin.