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Recommendation on manuf. approach for internal gear part

C

CharlieM21

Plastic
Joined
Sep 7, 2007
Location
Massachusetts
The picture below shows a part I am interested in having made, quantity approx 100. Material brass. OD 1.030". Solid ring portion ID 0.775", tooth ring ID 0.727". Solid ring thickness 0.015", tooth ring thickness 0.011", flush with back of the solid ring. The gear ring as shown is just a schematic representation, not the actual tooth shapes.

GJSETA9162.jpg


Any recommendations on the best manuf process for having this done?

Thanks.

Charlie
 
Because of the step at the teeth, you might edm a bunch of blanks, like washers, then turn the step in a lathe (fixturing might be tricky, them being so thin), then back to edm for teeth forms. Instead, could you coin them?
 
Another way: Cut your ~24" tube or bar into (10) 2.25" blanks. Chuck on 1/2". Turn the O.D. bore the I.D. rotary broach the spline. Skin cut your .004" step, then part off to size. If your parting tool is setup correctly you should be able to get a good straight/size finish. If you don't have a rotary broach turn the blanks to finish O.D./I.D. (you may be able to use longer than 2.25" in this case, ask your E.D.M. guy) then get the teeth wirecut, then back to the lathe for turning the .004" step and parting off. I would definitely investigate the laser cutting method if the accuracy is good enough.
 
I would look at laser cutting them from sheet and the fixturing them to a backing plate on a lathe and try turning the teeth to thickness, I suspect that turning the teeth may be difficult so as an alternative I would look at a tool post grinder to get the thickness. A modern laser can cut this part very acuratly extremly fast and the whole order of a hundred would take less then an hour. Wire edm would be very slow in comparison and much more expencive. If you have trouble finding brass sheet that is .015" you should look for sheets of brass shim stock which can be had in .015"
 
I would think you will have problems with the .002 step on the teeth


so I would start with a solid bar 6" long, drill on a lathe and broach the teeth wherever

then put it back on a lathe and finish cut and part off one disk at a time

much more information is needed as to how the finished product will be used and whether the designer is playing with a full deck of cards as well as tooth shape and tolerances

this of course will take some time, but if this is what you want you just have to pay up, point being: I can make it faster and better and maybe cheaper longterm than the next guy, provided you are telling me what you really need

I have worked in methods for over a year and hardly ever got a print that had all the numbers I needed, causing my superiors to call back to RCA, IBM and other big names

this thing sure don't look like it will be mechanically useful
 
Les, you kidding? It's gonna be .015" thick brass. Nothing easier or quicker in the world to deburr if it does raise a burr. I'd use a steel 6" ruler and just drag it across the finished part, that'll remove any burrs in one swipe. On another note, if you could get a higher qty order you might be able to stamp them out of .015" shim and also stamp in the .004" step in the same op. Wille, the one side is flush, so you'd need a .011" piece and a .004" shim, if that'd work.
 
Les is correct- lots of folks who want gears cut
figure that they will just have a "stick" of gear cut and them part them off without realizing what a deburring nightmare it will be. Even brass will burr up, and the burr will not be perpendicular to the cutoff surface- it will be in the tooth space where is is hard to get to. Trust us, we've been there!
Dan
 
You're not the only ones who've "been there." A deburring nightmare is stainless or inconel/etc where you can't reach the burr except with a 6" long deburring tool, inside a 1" bore...brass is a walk in the park. But I digress...

And besides, Charlie doesn't seem to give a rat's arse anyways. :D
 
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