Can I use my mill (Bridgeport VMC760/22) to punch holes? Before you lads blow up on me... hear me out.
My manual says the Z-axis max thrust force is 1975 lb.
The hole I'm trying to make is very small ~0.080 and in thin material 18 gauge. The total calculated force required is ~900lb. So less than 50% axis load.
Now I understand that my machine is old and was not designed to run like a universal machining head (the ones that can run static lathe tools in the head). Also thrust bearings aren't designed to take a thrust load without spinning. Well they kind of are, but its not good practice.
So anyways, my plan is to hold a custom made punch in my spindle and program it to punch a bunch of holes in some thin alloy.
I cannot plasma, laser or waterjet cut the holes. Lastly I do not have a sheet metal punching machine.
Why not drill it? because the material is a special alloy. It is absolutely terrible to machine. It's closer to Ti Gr2, but weaker. The material tends to "snag" like duplex stainless or hastelloy.
A traditional 118-140 degree tip drill will not work.
I've tried a 3 & 4 flute carbide end mill and plunged into into the sheet and the overall hole quality is good. But the cycle time and tool life is terrible. Also I risk scrapping the part if the the end mill wears out or a flute breaks. This causes the remaining flutes to snag into the metal which rips the metal and breaks the end mill.
Flat bottom drills also did not work, they aren't sharp enough and they still require far too much pressure. So it just galls and melts the plate.
and I already punched a few dozen holes. Quality is perfect, cycle time is great, tool life is excellent.
now the question is... should I run my spindle at low RPM so the thrust bearings can better distribute the load?
My manual says the Z-axis max thrust force is 1975 lb.
The hole I'm trying to make is very small ~0.080 and in thin material 18 gauge. The total calculated force required is ~900lb. So less than 50% axis load.
Now I understand that my machine is old and was not designed to run like a universal machining head (the ones that can run static lathe tools in the head). Also thrust bearings aren't designed to take a thrust load without spinning. Well they kind of are, but its not good practice.
So anyways, my plan is to hold a custom made punch in my spindle and program it to punch a bunch of holes in some thin alloy.
I cannot plasma, laser or waterjet cut the holes. Lastly I do not have a sheet metal punching machine.
Why not drill it? because the material is a special alloy. It is absolutely terrible to machine. It's closer to Ti Gr2, but weaker. The material tends to "snag" like duplex stainless or hastelloy.
A traditional 118-140 degree tip drill will not work.
I've tried a 3 & 4 flute carbide end mill and plunged into into the sheet and the overall hole quality is good. But the cycle time and tool life is terrible. Also I risk scrapping the part if the the end mill wears out or a flute breaks. This causes the remaining flutes to snag into the metal which rips the metal and breaks the end mill.
Flat bottom drills also did not work, they aren't sharp enough and they still require far too much pressure. So it just galls and melts the plate.
and I already punched a few dozen holes. Quality is perfect, cycle time is great, tool life is excellent.
now the question is... should I run my spindle at low RPM so the thrust bearings can better distribute the load?
