[Shane39]

Hey guys. Lately I have been working a lot with delrin. It is great to machine but for the life of me I cannot get a good surface finsih when flycutting (facing) the part. I have been using a 3" face mill and have tried every speed and feed. Can you guys suggest another type of cutter for delrin specially or some speed and feed advise. Thanks

[BJ-DEKA]

is it a insert face mill? if so that could be the problem delrin likes a nice sharp point on the cutters tips and inserts usually have a corner radius. a fly cutter that uses cutter blanks like you use in a lathe works well just grind that blank nice and sharp.

BJ

[Geof]

Which are you doing; flycutting, which uses a single point tool very often HSS, or face milling, which use a head will multiple inserts very often carbide?

If you are face milling with carbide that can give you a poor finish on Delrin. Most carbide inserts do not have a really sharp edge; you can see it easily with a powerful magnifying glass, the edge has a minuscule radius. This means the Delrin gets rubbed instead of getting cut so it tends to roughen up.

If you are flycutting with a HSS tool you need to sharpen it with zero top rake and have a really fine sharp edge. You also need to make sure the corner is not sharp but is ground to a bit of a radius so the edge in contact with the Delrin is wider than the distance you feed per revolution.

Also you need to be sure your head is correctly trammed. Even a small misalignment over a 3" diameter will leave noticeable semicircular grooves in the face.

[BJ-DEKA]

well put

[Shane39]

Hey guys. I am facemilling. I am using insurts that are specified for aluminum. They do have a radius on them so i guess this would be my biggest problem. What kind of insirts do you suggest or should i be using a different tool all together. I will do what ever is best. Thanks again!

[BJ-DEKA]

i would say go with a flycutter like these http://www.use-enco.com/CGI/INSRIT?P...&PARTPG=INLMK3 you can just buy blanks and grind them however you need for different materials. blanks are cheap and reusable as shown in the list on that page.

[djr76]

Be aware, I cut very large amounts of Delrin, going to fast with the cutter will actually tear threads (not machine threads) from the surface. I go between 3000-4000 rpm @ .004-.005 ipt using inserts for aluminum that are very sharp on the edge (45 deg facemill with sect/sekt/ inserts).