Bit Selection help for CNc accu-cut Kr

[scs2003]

Hi I am new to to the forum and new to this type of computerized router (Acc-cut KR).
i mainly use the router in lettering as i am in the sign making business.

i have worked out the running of the router no problem and the router is working beautifully. the only problem i have is trying to understand the types of bits i should be using and also the feed and speeds.

i mainly cut 3d lettering from 20mm thick plastic = ( not sure of the exact name of it) and also 4mm aluminum/plastic panels where the sheet of plastic is covered with thin aluminum on either side (the aluminium sheet covering is about half a mm thick.

i am using 6mm router bits for both as recommended by the machine suppliers.

the problem i am having Alu/plastic, at first the cut edge is smooth and is after few letters cut edge i rough and the aluminum would lift up giving me burrs on the edge. Some time i cut 2 to 3 board full of lettering before this happens and some times it happens after just few letters.
the feeds and speeds that i am using are:
feed 18mm per second
speed 18000 RPM
thinking i have fouled the bit, i change it and again it goes good for few cuts and then does the same thing.:mad::confused:

the other problem i have is with the 20mm thick plastic is i cut the lettering in two passes 11mm at a time. the router bit doesn't last long before it edge become rough and the shaving stick to the sides of the cut edge.
the feed is 15mm per second
and the speed is 30 RPM.

what am i doing wrong. could my feeds and speeds be all wrong and what should i be using. any feed back would be appreciate it.:mad::confused:

[danilom]

You are cutting 4mm Alubond panels, and you are cutting it too slow. Use 4mm spiral bit in one pass and feed it at least double than 18mm/sec, 36mm/sec or 2 or 2.5m/min.
Also its too much of RPM for a 2 flutes bit, try lowering it to 14k or using single flute bit.

Also for plastics I think 11mm pass is too much for a 6mm bit, you are clogging the 6mm narrow channel with hot chips. When I cut 35mm thick PE I used double flute 6mm and cut 4mm pass with 2.8m/min and around 12.000 RPM. And you need to blow the chips out of the channel with compressed air to get the finest quality edge.

If show us the bits you use we might help more.