What's new
What's new

How sharp is the cut by a flat-nose end mill

dsela

Plastic
Joined
Dec 28, 2015
Hi,

I'm trying to design a mold for a rubber wiper blade, which needs to have a very sharp 90 degree edge.
Theoretically it could be machined using a regular flat nose / square end mill with a diameter of 2 mm - I'm wondering what is the minimum cutting radius i can ask for on the inner edge.
I've attached a sketch that shows what edge I'm referring to.

Thanks
 

Attachments

  • Capture11.JPG
    Capture11.JPG
    21.9 KB · Views: 209
How about that inside 90 degree corner in the picture? Going to be hard to cut that with a endmill


Sent from my iPhone using Tapatalk Pro
 
I have a customer who years ago had to make a group of copper parts with a minimum .001 sharp corner. They had to work the parts by hand under a microscope with super fine wet sand paper in the same pattern to make the edge conform. It was like two swipes one direction and then turn 90 degrees and two swipes on the other surface to push the final grain of the material to the sharpest edge they could get.

Of course the part was an EDM electrode for a high end connector body. I wonder how tight a corner an EDM could hold with such an electrode.
 
I have a customer who years ago had to make a group of copper parts with a minimum .001 sharp corner. They had to work the parts by hand under a microscope with super fine wet sand paper in the same pattern to make the edge conform. It was like two swipes one direction and then turn 90 degrees and two swipes on the other surface to push the final grain of the material to the sharpest edge they could get.

Of course the part was an EDM electrode for a high end connector body. I wonder how tight a corner an EDM could hold with such an electrode.

The rad will be at least equal to the over burn.
 
Hi,

I'm trying to design a mold for a rubber wiper blade, which needs to have a very sharp 90 degree edge.
Theoretically it could be machined using a regular flat nose / square end mill with a diameter of 2 mm - I'm wondering what is the minimum cutting radius i can ask for on the inner edge.
I've attached a sketch that shows what edge I'm referring to.

Thanks


Dont worry about it, your endmill has much less of a radius (or corner break) than what you can injection mold for a sharp corner into a cavity wall, as you have shown.
 
You can ask or require whatever you like.
You will just have to pay for it.
Under .005 means very serious money as you are looking at one tool per part max or even less.
.005./.007 gives some room but most if specked here you will get .010 as most actually can't measure this corner that close.
At 010/.015 tail end of the rad you get into standard shop work. It's not a true .012 rad and is mostly 6 or 7 but it "pulls out" in a slight ramp on the tips to this range.
Endmills not only knock off a radius on their corners with use, they grow a leadin line to that radius.
Bob
 
That pocket you show will have to be an edm burn. With high end poco electrode material, and picking out the corners, and having enough electrodes, you can achieve that shape.But it would be tough to get any sharper than .001 rad. No worries though, if that is a rubber mold you won't fill that tight edge anyway. Unless you vent the hell out of it, and by the looks of your sketch that was not part of the equation. You want a SHARP corner there that will actually FILL with material, you wire out the pocket and slide in an insert from the backside for venting.
 
Hi,

I'm trying to design a mold for a rubber wiper blade, which needs to have a very sharp 90 degree edge.
Theoretically it could be machined using a regular flat nose / square end mill with a diameter of 2 mm - I'm wondering what is the minimum cutting radius i can ask for on the inner edge.
I've attached a sketch that shows what edge I'm referring to.

Thanks

You can ask for as sharp as you want, as Carbidebob said, you will PAY for it though.

Can you make that cavity in pieces? If you could live with 4 parts, ground to a good finish, bolted and doweled together, not sure if rubber would possibly flash with a design like that though....?

Another idea for a 2 piece design, a wireburned square thru (we run .008" which would give you a theoretical .004" cr), then a ground plate bolted to one side to 'close' it off?
 








 
Back
Top