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countyrunner
12-26-2005, 08:59 PM
A friend I work with has a part time sharpening business and was asked by a local manufacturing co. to sharpen 3inch stainless steel discs used to cut paper the ice cream drum sticks they make are wrapped in. The discs have a sharpened outer edge and are driven by a shaft in the center of the disc. I made him a fixture to hold the disc while sharpening which worked good. He gets a very sharp edge with the same angle as new, but the problem is they only hold there edge for an hour of cutting the paper. Not nearly as long as a new disc. He wants to know if there is anything he can do to make the edge last, like annealing etc. that may have been done at the factory after sharpening. I do have a small kiln he can use if that would help. Not sure what number of stainless it is. Just looking for some of your expert advise on what he could do that maybe isnt so complicated. thanks

CCWKen
12-26-2005, 09:20 PM
I'm no expert but my first thought would be to use a tool steel rather than stainless steel. Unless SS is required by "food handling" rules, it makes a lousy paper cutter. I think annealing would make it worse.

What is the cutting edge and what is it cutting against? A shear doesn't need a knife edge. There may be too much clearance between wheels. Scissors are almost self-sharpening because the blades contact each other.

countyrunner
12-26-2005, 09:40 PM
CCWKen, Im not sure what the cutting edge is, I will have to ask him. Im sure the disc it is stainless steel though. thanks

Kansas_Farmer
12-26-2005, 09:46 PM
On our disc blades we run a bead of 'hard surfacing' material. It might not be feasible for ya in this application, but I can tell you doing that will increase the life of the blade by about 200%. Those blades are razor sharp and stay that way. The stuff we've used is Tunsten-Carbide rod that you 'weld' on with a Oxy-Actylene torch.

Dunno if this would help at all, but I thought I'd throw it out.

JCHannum
12-26-2005, 10:00 PM
I had similar problems with packaging machinery, the resharpend blade does not seem to hold up as well.

One thought is what is he using for coolant? I would think flood cooling would be required.

The other thing is to get a good look at a new cutter and see how the factory sharpens them. Try to get an idea of the grit of the wheel and how it is oriented in respect to the cutter blade.

Kansas_Farmer
12-26-2005, 11:01 PM
I think you'll want to roll those disc blades to sharpen them, if that's at all possible in the appication in question.

japcas
12-27-2005, 03:59 AM
I would definetly try to get a look at one of the new discs before it is run. Maybe they are hollow ground and he is flat grinding them or vise versa. Don't know what kind of grinder he is using, but the way the wheel is presented to the disc will change the geometry of the cutting edge. Looking at a new one should give an indication of how they were made. Definitely need to keep it cool, but he should know this if he sharpens other tools.

PTSideshow
12-27-2005, 06:15 AM
Paper products are the worst thing to cut for trying to keep a blade sharp.All the fore going info about looking at a fresh one and coolant applies. Also the backing plate that it cuts against can dull it faster if the company replaced it with something stiffer. and do they adjust the tension on resharpened blades higher than new ones.

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Glen
Been there, probally broke it doing that