Using a 0.006" slitting saw on an extremely hard and tough metal. yea or nay?
Hey all, I'm in need of some advice on how to should proceed here.
I need to use a slitting/slotting saw on a rod of Hiperco-50A, also known as Vanadium Permendur, which is a 49% Iron, 49% Cobalt 2% Vanadium alloy with excellent magnetic properties, however it is extremely strong, tough, and hard. The closest thing I feel at liberty to compare it to is a very tough stainless steel alloy, since not only is it super strong, but it also has the tendency to work harden. Here is the datasheet for the metal, if anyone was interested:
Carpenter: Hiperco 50A Alloy
My part is hot rolled, so i would hope that it'll be a little bit softer than the cold rolled properties which are listed. The rod's diameter will be about 1/2in.
What I want to do:
I want to mill 3" long slots down the rod, about 0.2" deep. Using a manual brideport vertical mill, the part will be held horizontally in a chuck with a dead center supporting it at the other end, and I want to know if you guys think that i can get away with using a 0.006 slitting saw, (i need to make the slots as thin as reasonably possible) or am i out of my mind to think that an HSS slitting saw that thin can cut a piece of metal as tough as hiperco 50?
The other issue, i have not yet bought any slitting saws, and I was wondering what you guys think about these here on ebay:
High Speed Steel Jewelers Slotting Saw Blade 1 1 2" x 006" x 1 2" MALCO New | eBay
NOS Circular Tool HSS Slitting Saw Blade 1 3 4" x 006" x 1 2" 30 TPI w Slot | eBay
or if anyone can recommend somewhere to buy the proper slitting saw for this job.
The only other time i have done anything like this - was using the same setup to mill slots in a rod of 12L14 steel, using a 1/64 (0.016") slitting saw. And yes, i do realize that this will be a whole different animal since 12L14 cuts like butter compared to this stuff.
also should i use an oil based coolant, or water based?
Last edited by stickshifted; 07-01-2013 at 03:35 PM.
I for one wouldn't even attempt it. Blade life would be very short indeed.
Inadequate column strength to even make a straight cut (it wandered) in bearing bronze was my experience - which is neither hard or very tough
Send it out to a wire eroder ,.2" x3" long is a lot for a tiny saw in anything let alone a difficult matrial.
I have done a lot with slitting saws, but nothing like you are trying to do...
My first thought was wire EDM but if that isn't an option, someone with a sinker EDM could make a small electrode. Probably wont be cheap. But then again blowing apart 3 carbide saws won't be cheap either. The HSS will wear FAST on that material. If you try it go SLOW and use oil.
Just my .02
Extremely hard is like 60+ rockwell c. Thats harder than your saw.
Originally Posted by stickshifted
A carbide blade the size you're talking in a BP wouldn't exactly be a cup of tea. Plus the saw would probably cost more than wire edm.
I would have considered this an edm job right out the gate. I would guess your in for a lot of headaches otherwise.
Data sheet says it a cobalt alloy, not chrome. It also says it's a 'soft magnetic alloy'. I didn't find any hardness values, but properties under strip stock shows a tensile of about 100k annealed. There's also a machinability chart that shows some reasonable speeds for HSS.
Could something like this be done with an an abrasive cut off disk, proper RPM and a bath of coolant and slow feed?
I recall seeing slitting of some sort of collets using a manual mill and plenty of coolant as an apprentice. However that was more like 0,5 mm.
20 Ultra Thin Cutting Separating Discs Dremel Rotary Tool Jewelry Dental 009" | eBay
(Dress with a diamond to 0,006")
Like wesg says, this is a soft magnetic material. Not hard, no chrome. Are you gapping a core?
That is interesting. My regular Dremel cutting disks are about .038". I thought they had to be handled with care. This implies a high speed spindle or a Dremel support. Do you feed according to the pitch of the Dremel whine?
Originally Posted by cypherp
I've machined A LOT of Hyperco 50... and have to agree with others, while it MAY be possible with the right setup, by the time you spend bucks for material samples, the tools, and come up with one, wire EDM would be half the price. I would go with the wire this time.
Ok, first of all i apologize about listing it as 49% Chrome, Yes it is indeed 49% Cobalt, my mistake.....i posted this last night at 2:00am - im definitely not too conscious at that hour...
Originally Posted by Archer120x
When a material is said to have "soft" magnetic properties, this does not have much bearing on its physical hardness. In magnetics terms, "soft" refers to the fact that the material retains very little magnetic field when the external field is turned off. This is the case for the silicon steel used in transformers and motors. An example of a "hard" magnetic material are permanent magnets like refrigerator magnets or computer hard drive magnets. They retain most of their magnetic field, when the external magnetizing fields is turned off. An interesting thing is that there are many soft magnetic materials that are indeed physically soft - such as pure iron, mild steel, and silicon-steel. However many types of ferrites (used in inductors, switching powersupply transformers) as well as Hiperco 50 are physically hard but they are indeed "soft magnets."
The Rockwell hardness of this material is 36C in cold rolled form. I should have clarified. It is hard, but certainly not harder than than HSS. Here is a better datasheet, and the machinability table that I should have included:
Originally Posted by John Welden
MatWeb - Online Materials Resource: Hiperco 50A Cold Rolled
Carpenter Hiperco 50A Machining
This one shows turning speeds for both HSS and Caribide:
High Temp Metals Permendur 2V Hiperco 50A Information
The issue with the material datasheets are thus: My part is hot rolled, so it will not be as tough as the cold rolled variant. However i cannot trust the material data for the annealed parts either, since those annealed parts will definitely be softer than my hot rolled part. The annealing done to Hiperco50 is way beyond my budget, and involved bringing the part up to about 1600F in a "dry hydrogen atmosphere" (sounds like a hindenberg waiting to happen) and its used to make the material more magnetically soft than normal.
Since you asked, I am doing research on the improving the efficiency of coilguns, mine is also known as a Linear Reluctance Accelerator. I have a large high voltage capacitor bank, and i use a huge transistor to dump all of that energy into my coil, which then builds up a large magnetic field, which magnetizes and accelerates the projectile. Many hobbyists like to build these devices, yet there is very little scientific research done into this particular type of coilgun. My coilgun is somewhat similar to this one on Sam Barro's page:
PowerLabs Coil Gun Research
It says in the ebay ad that they recommend using 10,000-12,000 rpm. those sound pretty cool, but sadly i don't think the shop im using has a mill with any spindle faster than 4200 rpm, and the manual mills only go up to about 3000rpm.
Originally Posted by cypherp
Is the depth of the cut at all crucial? If so, it'll be hard to regulate because those discs are likely to get consumed pretty fast. I've worked with that size disc frequently, and I suspect that, on something hard like you describe, you will be able to easily watch the disc get smaller quickly.
Thank you for the heads up. Luckily the depth is not too critical, ideally i would want my depths to be within 5 thousandths, but if one slot comes up 0.010 short, that'd be fine. The only thing is that I do need to make these slits as thin as possible, since i want to remove as little material as possible. Though the slits do need to be deep enough since they are there to reduce the eddy currents that will be present in a non-laminated core. The same way that a transformer has less eddy current loss with 0.004in laminations, compared to a transformer with 0.016in laminations, the more slits that i can cut into this projectile, without removing too much material, the more efficient my coilgun will be.
Originally Posted by Ron Hofer
I am curious as to just how one would use wire EDM to cut a slot that does not go all the way through the material. I can see sinker type EDM working quite well, if slowly. I have read some articles on the making of simple EDM equipment and it would seem to me that someone with some electronic capability, and a machine shop, wouldn't have too much trouble fabricating something useful. I like the magnetic accelerator project, I played around with it a bit myself some years ago and had some fun. Just shooting nails around the shop, nothing as fancy as you are doing. Good luck with your project.
For the $6 the saw costs I would buy a couple, then make an arbor to hold them that supported the saw to within .25 of the outer dia, more or less clamp it between two washers that are part of the arbor. Stiffened that way I would think the saw would be quite rigid. Then I would give it a shot in some test material and see what happens.
I would go into it thinking I could pull it off I have cut 4140 pre heat treat with similar a .031 saw that was not not nearly as well supported. I know nada about that alloy you mentioned so it may present some problems that I would be ignorant of.
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