I'm lettering some aluminum rack panels. Single line letters, 0.15 to 0.5 high, 0.032 line width, essentially just cutting a square groove which will be filled with enamel for contrast. Cutter is 0.032 carbide, 2F, uncoated, running at 27000 rpm at 10 ipm with 0.005 DOC, 0.0002 per tooth, air blast droplet cooling. Cutter is running in my 15-27K rpm aux spindle on an 1100, and has <0.0002 runout. Stock is mounted with tape/glue, flycut flat prior to lettering.

This works, but I'm essentially melting and plowing the groove in the panel- very obvious bead. Same happens at slower ipm, less depth. Cut depth is consistent, and a post lettering flycut gives a decent result. Not breaking cutters. I can live with it. But it's meatball machining. Embarrassing.

None of the rack panel manufacturers (Bud, Hammond) list an alloy type, but this is soft, gummy, sticky aluminum. Miserable to machine. I've heard that it's some variety of 6063, which seems possible.

Cutting parameters in this ballpark work fine on other alloys (7075, half-hard 6061). Crisp edges, no melting. The usual things I vary to tune the process -lower ipm, DOC- haven't helped here. Haven't tried an engraving cutter yet.

Does anyone have a proven, working cutting recipe/cutter in rack panel aluminum? Anyone know for sure what this alloy is?

(NB- I've read Ray L's thread from 2013; everybody agrees it's miserable stuff. But that said, what actually works for milling this goo?)

Later: carbide engraving cutter- effectively a sorta pointy D bit- is no better. Just shoves the stuff aside. No surprise.

1/8 shank HSS 0.032 cutters are not common. For some reason, they're all 3/16 shanks. Precision low-runout collet ordered.