Cutting plastic for first time, perhaps I am going wrong a tip or two be great thanks

[suesi34e]

Hi guys,
I have to cut some 10mm to 10.8mm grooves at a depth of 39mmin HDPE. I am thinking of the following:
10mm 4 tip carbide end mill 50mm long
4000 rpm which is my max spindle speed x and y feedrate 1800mm per minute 2500mm max for my mill
300mm in the z cutting at 3.9mm per pass 10 passes.
I believe weld back could be an issue. I was thinking of using an airline to try and blow the loose away but I thought I may just do more damage than good and stop the waste from exiting the groove. I got to thinking perhaps a vacuum may be better to try and suck the waste away.
I also have to surface finish the HDPE. I was wondering if Iwould get away with a 38mm TCT surfacing bit I use in my router I think I used to run it at about 12000rpm so I am not sure what it would be like at 4000rpm
I am pretty clueless when it comes to plastic and metal so Iwill welcome any thoughts or criticism.
I downloaded G wizard but I found it a little confusing and I have to crack on with machining the part I will have to have a look over it when I get more time!
All the best and many thanks for any help in advance
Suesi

[phill05]

I have to cut some 10mm to 10.8mm grooves at a depth of 39mmin HDPE. I am thinking of the following:
10mm 4 tip carbide end mill 50mm long
4000 rpm which is my max spindle speed x and y federate 1800mmper minute 2500mm max for my mill
300mm federate in the z cutting at 3.9mm per pass 10 passes.

I have just been cutting Nylon 6 and found 1 or 2 flute upcut works best it throws the chips out great no need for airline just use vac to clean up.

Phill

[suesi34e]

Hi Phill,
Thank you for your reply. I am glad your cutters worked for you. I will have to try and source some 1 or 2 upcut cutters for future reference. I will try with the 4 flute I have unless I am told it is the wrong cutter and that way it will give me a comparison for when I get the cutters you mention.
Many thanks
Suesi

[Robin Hewitt]

I suppose it is worth mentioning once in a while for newbies... if you want to surface anything with an end cutter you need non-plunging tooling.
If your tool cuts all the way to the middle it will leave a graunchy, chewed up line behind when you go sideways

[jamesgates1000]

I would definately recommend a 1 or 2 flute cutter with a slow spiral, your 4 flute cutter doesnt leave much chip clearance. I would rough first then use the 0.8mm left to finish both sides, very sharp tooling and flood coolant/high pressure air recommended.

[suesi34e]

Hi James,

Many thanks for your help and the pointers. I will try and get some one and two flute cutter for the next job. I had to crack on with what I had for know. Perhaps Trend cutters will be good if you or anyone could provide a cutter reference that would be great so I could the right ones. I have a coolant tank on my mill but know coolant that is another job I will try the compressor though!

All the best

Suesi

[suesi34e]

Thank you Robin,

I cut the little job without any balls ups. I was most worried about damaging the machine, cutter or material. That was all fine and the finish will do from the 4 flute for the job in hand. I will get some better cutters perhaps some Trend one and two flute ones.

Many thanks

Suesi