vmipacman
Cast Iron
- Joined
- Nov 21, 2014
- Location
- Virginia, USA
For those who have real world experience with 3D contouring...
I was asked to estimate machine time for a plate with kinda a rolling hill surface. The plate in question is 18" x 30" x 5" tall max and 2.5" tall at the min. So picture a rect plate with the center pulled up and the slide sloping off. The part approximates a small section of the exterior curve of a large pressure vessel (done shaped). Just that surface. Just picture a piece of paper flat on your desk and push the ends together slightly. No other features, small areas or gotchas.
The plate is 304 SS.
The material needing to be removed is approx 500in^3.
The surface should be "good" but not polished necessarily.
The mill is pretty stout, CAT50. Lots of torque but rpm limited to about 4K.
I used HSMWorks to do some quick tool path calcs.
For roughing I came up with a pretty conservative estimate of 6.5 hrs using a 3" APKT facemill. With a high feed 4" insert cutter, computer says I could do it in less than half that time! Roughing to .02" of the surface.
For finishing I used a 1-5/8 insert ball mill. Taking .03" steppover passes at ~30 ipm. That gives a finishing time of 9-10 hrs. And in my (limited) experience that will yield a pretty smooth finish, maybe with some scuffing at the ball mill center. With a few hrs of handwork you could really finish it out nice.
I estimated that in 20 something machine hrs you could have it done, plus a few hrs for some easy hand work (if needed).
I heard another shop that does foundry patterns pretty regularly estimated literally 100's of hrs of machine time!? They have newer equipment, higher rpm's and feedrates.
What am I missing in my approach?? I'm sure i am under estimating some, but I either don't understand the 3d strategies at all or the other shop is over complicating.
I was asked to estimate machine time for a plate with kinda a rolling hill surface. The plate in question is 18" x 30" x 5" tall max and 2.5" tall at the min. So picture a rect plate with the center pulled up and the slide sloping off. The part approximates a small section of the exterior curve of a large pressure vessel (done shaped). Just that surface. Just picture a piece of paper flat on your desk and push the ends together slightly. No other features, small areas or gotchas.
The plate is 304 SS.
The material needing to be removed is approx 500in^3.
The surface should be "good" but not polished necessarily.
The mill is pretty stout, CAT50. Lots of torque but rpm limited to about 4K.
I used HSMWorks to do some quick tool path calcs.
For roughing I came up with a pretty conservative estimate of 6.5 hrs using a 3" APKT facemill. With a high feed 4" insert cutter, computer says I could do it in less than half that time! Roughing to .02" of the surface.
For finishing I used a 1-5/8 insert ball mill. Taking .03" steppover passes at ~30 ipm. That gives a finishing time of 9-10 hrs. And in my (limited) experience that will yield a pretty smooth finish, maybe with some scuffing at the ball mill center. With a few hrs of handwork you could really finish it out nice.
I estimated that in 20 something machine hrs you could have it done, plus a few hrs for some easy hand work (if needed).
I heard another shop that does foundry patterns pretty regularly estimated literally 100's of hrs of machine time!? They have newer equipment, higher rpm's and feedrates.
What am I missing in my approach?? I'm sure i am under estimating some, but I either don't understand the 3d strategies at all or the other shop is over complicating.