Laser Cutting Gears?

It depends on your definition of precision. If they are low A.G.M.A. numbers, then it might be possible. For the more precise gears, say grade 8 and up, you must hob until you reach grade 10, then grind to reach grade 12. And of course you can only make spur gears with this machine.

Unless you wish to first finish the teeth, then the bore true to the teeth as is done in some successful shops.

Past that, I do not know how deep the laser cutting hardens the metal, and how much at that-perhaps a negligible amount. Perhaps use the laser to "rough" the teeth on the gears and then finish them with a hob or grinder? Now there is a possible idea if the teeth are quite coarse and deep.

But past all that. If you are successful with the precision class desired, then you can eliminate hob sharpening, special hobs, etc. But what is the true cost of operating the laser in terms of power requirements, machine tool investment, wear and tear costs? I think that must be answered before a thorough advantage is explored.

But, if one were cutting teeth on say, a sector gear, then it sounds like the way to go. I would have further concerns about the release of metal stress and whether that would cause further composite errors. But the use of a Fellowes gear tester would tell you what are the true results. Good luck-let us know.

Ing. Robert Forbus

Hello,

One has to remember that when you lasercut thick material, the edges are not perfectly perpendicular to the surface. I think this fact will be important for the functioning of the precision gears. Hence probably one can use the laser cutting only for rough or low precision gear cutting.

The problem of not having perpendicular edges is going to be very important for the functioning. The wear is not going to be constant in all the contact surface of the tooth and it is going to produce overloaded zones and zones without load. The danger of having surface problems grows very much in this overloaded zones. Is the same effect as if you have disaligned shafts.

Another problem is the tooth geometry. The generation process have the exact teeth form because of its natural movement, but the geometry is really complicated. To reach this geometry in a short time with a laser is not going to be easy.

As it was said before, you can have low precission gears, but machining this kind of gear is really cheap because the process time is very short. Anyway, for this gears you can have the possibility of having sintherized wheels, much cheaper for big productions. Perhaps you can find a market in little productions where the gears quality is not very important (where the noise and the wear are not important).

But, try it. If we don't try to do new things we are not going to advence. Good luck.

The drawbacks of which I am aware are localized heating and possible decarburization of the surface. This will result in a soft gear face. Lack of perpendicularity of the face to the bore will also be a problem. The gear geometry will not be correct nor will the pitch diameter by concentric with the I.D. Other potential problems are recast on the surface of the gear casued by the burning action of the laser. I have heard about people who are using 5 axis wire EDM machines to accomplish low cost gear machining with minimal clean up after completion. The EDM is very precise although recast can also be an issue here as the finished surface can be quite rough and pitted in appearance. This surface is about .003-.005 deep and can often be stoned off after processing. Good Luck