Machining a Keyway

[logosys]

How in the world do lockmakers machine a keyway? Most of the equipment that I deal with on a daily basis is stamped, done on a lathe or drilled. A keyway seems like it's going through too much material to stamp, and it's not circular, so it's not done on a lathe...

Is it just a rod cast in a mold with the keyway shape (and then slid off)???

[Romstar]

They are first rough cast, and then stamped. Or, more accurately, they are coined.

A finished key BLANK is made in much the same way as a quarter or any other coin. You first have to have a slug of the appropriate materials, and then it is inserted into a high pressure stamping machine where the coining process takes place. The slug is double struck, and a thin layer of the metal actually turns to liquid under the pressure of the press.

Another method is used on cheaper blanks, and that is the rough cast machining method.

A blank is cast to the appropriate shape, but the side mills are not in place. As the blank passes through the equipment, cutters mill the grooves into the sides of the keyblank.

Even if your keys don't say where they were made, you can almost always tell which method was used by closely examining the grooves in your keys.

Romstar

[logosys]

They are first rough cast, and then stamped. Or, more accurately, they are coined.

A finished key BLANK is made in much the same way as a quarter or any other coin. You first have to have a slug of the appropriate materials, and then it is inserted into a high pressure stamping machine where the coining process takes place. The slug is double struck, and a thin layer of the metal actually turns to liquid under the pressure of the press.

Another method is used on cheaper blanks, and that is the rough cast machining method.

A blank is cast to the appropriate shape, but the side mills are not in place. As the blank passes through the equipment, cutters mill the grooves into the sides of the keyblank.

Even if your keys don't say where they were made, you can almost always tell which method was used by closely examining the grooves in your keys.

Romstar

Are the keyWAYs Cast, then finished?

[hzatorsk]

Gee logosys, You're the Mechanical Engineer... I was hoping you'd know

Perhaps some pieces are cast first, but I'd think precision milling/machine work would be the only way to get the tolerances needed.

If possible, like for plugs and pins I'd probably start with rod stocks as it would be much cheaper than casting parts.

Harold

[logosys]

Gee logosys, You're the Mechanical Engineer... I was hoping you'd know

Perhaps some pieces are cast first, but I'd think precision milling/machine work would be the only way to get the tolerances needed.

If possible, like for plugs and pins I'd probably start with rod stocks as it would be much cheaper than casting parts.

Harold

Hey, I know subsea oil production equipment, locks are just a hobby...
I originally thought of staring with rod stock, but how is the oddly shaped front face made? If it's just welded, it seems like it would fail under torsional loading...

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[logosys]

Ignore above question....

[Romstar]

Lock plugs are cast, and then finish machined.

The keyway itself is finished with an angled abrasive shaft. The rest if finished with standard machining.

Romstar

[logosys]

Lock plugs are cast, and then finish machined.

The keyway itself is finished with an angled abrasive shaft. The rest if finished with standard machining.

Romstar

Could you EDM the Keyway out?

[CaptHook]

Definately. But it wouldnt be cost effective considering time involved in edm machining, and that kind of precision isnt needed for the use.
Chuck

[Romstar]

Lock plugs are cast, and then finish machined.

The keyway itself is finished with an angled abrasive shaft. The rest if finished with standard machining.

Romstar

Could you EDM the Keyway out?

Cripes Logo, bear with me a little. Half of this stuff is self taught.

Please define EDM for my overworked brain. I volunteered three days for a community festival. I am not firing on all eight cylinders.

Romstar

[logosys]

Lock plugs are cast, and then finish machined.

The keyway itself is finished with an angled abrasive shaft. The rest if finished with standard machining.

Romstar

Could you EDM the Keyway out?

Cripes Logo, bear with me a little. Half of this stuff is self taught.

Please define EDM for my overworked brain. I volunteered three days for a community festival. I am not firing on all eight cylinders.

Romstar

EDM stands for "Electrical Discharge Machining" Basically, they zap the material and vaporize it. It's extremely precise, we use it a lot on Wellhead Casing Hangars that are made out of Inconel 625 (Probably the single hardest material to machine) It can "drill" a profile plus/minus a micron. It also has the advantage that it's a "no contact" machining process, so it doesn't strain the material at all (especially useful on work-hardening materials like Inconel)

On brass, you can slap out EDM parts pretty quickly, it's with steel and Nickel alloys that it starts to get time consuming.

If you were to machine a plug and a hull using EDM, the tolerances could be sick. Since the 18 Sigma on an EDM is nil, the elastic deformation of brass (or even nickel-silver for that matter) would extend the tolerance of the holes. In essence, you would create an "ideal" lock, where all the pins bind at once. The only problem would be the cost of that lock, as EDM isn't as cheap as milling...

Hmmmm, I might have to make a trip down to Houston this weekend...

[Chucklz]

On a purely technical note, I believe the process of actually fabricating the keyway in the plug is called broaching. Maby this will be a bit of a clarification, or perhaps I've just muddied the waters.

[logosys]

On a purely technical note, I believe the process of actually fabricating the keyway in the plug is called broaching. Maby this will be a bit of a clarification, or perhaps I've just muddied the waters.

How would you broach a paracentric keyway though? It seems like your file would break too easily...

[CaptHook]

Its very possible/feasible to broach them. Have the plugs keyway as part of the initial casting. A broach is basically a stepped punch that cuts material, they can be made in lots of different shapes.
So putting the plug in a press, and pushing the broach through would not be a problem. Add to that an automated system of flexible manufacturing, and it could be done rather quickly.
Chuck