Help with routing plastic.

[monalek49]

Hi Vectric Friends,
I was asked to help with a project for a friend. They want me to cut some plastic earrings from a 1/8th inch thick plastic.
The file is attached. I have not cut plastic before. I am using a 1/16 inch end mill so I can get the intricacies of the design. I am not sure at what speeds I should set the cut RPM and what is a fairly decent feed rate. I tried one cur at .125 and it did not go through and some of the plastic seemed to be melted or just gummed up. I can cut these out of wood pretty decent but not sure about plastic. I also have a
a .0492 end mill, that I could use to get better detailed routing. Any advice and thoughts would be greatly appreciated. I was laying others out to see where to place hold downs.

[Adrian]

Speeds and feed depends on the machine more than anything but the right type of bit is very important for plastic. I use what is called an O flute bit - https://routercutter.co.uk/solid-carbid ... e-plastics

[ohiolyons]

Precisebits has some incredibly small O flute bits.
https://www.precisebits.com/products/ca ... r-O_1F.asp

As a starting point, a general rule of thumb, speed up your x and y and slow down you RPM.

[martin54]

Wood is far more forgiving than a lot of other materials which means that for plastics you need to spend more time figuring out your speed & feed settings. If it is melting then you are creating heat which is not getting carried away so slower spindle speed & a higher feed rate.
Chip evacuation is very important, recutting chips just generates more heat My dust extraction is not the best in the world so when I am cutting materials like plastics or aluminium I use an airline directed at the cutting area. This helps in 2 ways, it removes the cut chips & it also helps to keep the tool tip cool. You don't need a lot of air, just a gentle blow that is enough to move the chips from the cutting area.
As others have said use a bit that is designed to cut plastics

[dealguy11]

Another thing to consider is direction of cut. I generally cut out wood in conventional direction, which gives me a smoother finish on my machine. I have found that I have to cut plastic in the opposite direction to get a good finish - if I cut it conventional then the chips stay in the kerf and it tends to melt.

Your results may vary.

[martin54]

Another thing to consider is direction of cut. I generally cut out wood in conventional direction, which gives me a smoother finish on my machine. I have found that I have to cut plastic in the opposite direction to get a good finish - if I cut it conventional then the chips stay in the kerf and it tends to melt.

Your results may vary.

That's interesting, I didn't try cutting in different directions, I just switched to using an airline to remove the cut chips from the cutting area

[TomWS]

O-Flute is the only way to go with plastics, its a single flute with a deep bite and upward lift so you get less chip jamming (which will cause melting). Keep spindle speed lower and feed speed higher than expected. There are lots of suppliers of these bits now.

I've used these on Acrylic, Nylon, PVC, Delrin, and HDPE. Precise Bits, Amana, SpeTool all have good choices.

Make sure your spindle & gantry are very rigid.