O-Ring Groove Help Needed

[TZ250]

What is a good way of cutting a O-Ring groove on a mill? I have a Milltronics Cent. 6.

The material is aluminum. I'm making a small threaded plug. I have a thread mill.

I could use a small endmill, but I think that it would be too slow. I've thought of making a endmill the correct O.D. and having a I.D. EDM'd inside. That would leave a small, thin cutting surface.

The O-Ring diameter is about 1". The thread that is above it is approx. 5/8" tall.

Thanks in advance.

TZ250

[msomerville]

I would grind a tool that would plunge down over the top of your threads and sweep the groove.

[TZ250]

That's what I was trying to explain. You did a better job!

So far, that seems to be the best / most efficient method.

[One of Many]

You could use a keyway cutter, but IMHO any milling cutter can leave lines in the seal finish areas that can become a leak point where the O-ring won't be able to provide a complete seal.


Another option would be a boring/facing head on the mill. They just are not all that convenient to use for fast production. Or find a method of holding the part in the mill spindle and a grooving cutter in the vise to turn the groove into the part using your mill.

Lathe turning the groove would be all around a better approach although a second operation. Of course turning the thread and the groove together would keep both on the same center.

DC

[Metal_twister]

slitting saw, or woodruff cutter

[mrainey]

These guys make indexable groove milling tools in just about any size or shape you're likely to need.

http://www.hornusa.com/

[ctate2000]

Use a woodruff key cutter. Look in MSC.

[Geof]

A possible disadvantage to using a keyway cutter is that the corners are sharp. This leaves a sharp internal corner at the bottom of the groove and depending on the overall design of the plug, whether it is subject to significant pressure, whether it will be removed and replaced frequently, you have introduced a stress raiser that is a perfect start for fatigue failure.

[pepo]

Seems some of these guys think this groove is in a bore or on an o.d. If I understood right this is a groove in a face. What is commonly called trepanning. You could interpolate this with an end mill or cut it with the hollow end mill you spoke of. These are simple tools to make if you have access to a surface grinder. Use a 2 flute end mill,stand it up with the end cutting lips parellel to the axis of the grinder spindle and grind out the middle of the end mill. This will leave 2 teeth sticking out,their width should be the width of the groove you need. Or you could make a steel body to hold two peices of HSS or carbide with set screws. There is no rule that says one tooth wont work also.

[TZ250]

Thanks for the replies. This part is under no real stress. Sharp corners will be fine. The O-ring groove is on a face, but has a 20mm thread protruding away from the face. The endmill would require a deep hollow to go over the male thread.