MILLING CAST IRON

I am trying to mill a piece of cast and having trouble dulling hss end mills - also tried a fly cutter with carbide tip- no luck Whats the best cutter for cast- Its pretty fine grain stuff.

Reply to
turnitdown
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If it's already been heat treated, which it has by the sound of it, then forget it. If it's in the soft condition it should machine like butter.

Dave Baker - Puma Race Engines

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Reply to
Dave Baker

Machining CI is just like getting a response from some of the posters on this NG

- you have to get under the skin first.

Most of your dulling-of-tools takes place when the tip drags against the glass-hard skin of the cast item. Take a frighteningly deep cut for the initial cut, right under the skin, and you mostly find the remainder machines beautifully. (Barring slag inclusions and other hard spots, of course)

If you take a half-and-half cut (some cutting and some rubbing) then you can kiss your tool goodbye. (on reflection - wish *I* could do that.)

HTH

-- Jeff

Reply to
A.Gent

Unless he's not cutting deep enough to get under any scale or sand.

John Martin

Reply to
JMartin957

With my Mill/Drill I had similar problems, it's difficult to get the rigidity to take a serious cut. Solid carbide end-mills, 1/2", worked like a charm. The off brands are available on ebay for not-so-much.

Reply to
John Hofstad-Parkhill

His carbide cutter should still have gone through that easily enough I would have thought. Maybe he'd like to say where this piece came from and whether it's fresh cast or possibly already flame or induction hardened like if it's a lump out of an old lathe bed or summat.

Dave Baker - Puma Race Engines

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I'm not at all sure why women like men. We're argumentative, childish, unsociable and extremely unappealing naked. I'm quite grateful they do though.

Reply to
Dave Baker

The color of the iron may be an indicator of your problem. If you have white iron, it simply won't machine, although it can be successfully ground. You mentioned it is fine grained, and that's an indication it just may be. Can you describe what you're trying to machine?

In order for cast iron to machine, the color of the material should be gray, just as the name implies. If it is, and you can't get beneath the skin and get good cutting results, it's likely that the iron is chilled. A furnace anneal can restore machinability.

If all conditions suggest your iron should be machinable, the best results you'll get will be with carbide, which resists the abrasion better than HSS. The grade you select is important to long life, though. You do NOT use the same grade for iron that you use for steel. Non ferrous grade carbide performs much better, so choose a C2 grade. Carboloy 883 is an excellent choice.

Harold

Reply to
Harold & Susan Vordos

Thanks Guys- I am trying to mill some slots on the side of my mill table on my Shopmaster 3 in 1 machine . I want to put some sliding stops on it. The material color is dark gray once you get below the finished surface. It must be hardened, so I will try the deep cut trick with a C2 carbide.

Reply to
turnitdown

I did a plunge cut with a 4 flute end mill, and then cut the slot longitudinally. Once I was below the surface it milled fine. I don't know how they harden those castings, but that surface is like glass. Once you break through it cuts easily from the side.

Reply to
turnitdown

If the surface is hardened intentionally, and it sounds like it is, the process is usually flame hardening. That was common on lathe beds of higher quality. Toughens the surface without hardening the interior.

Harold

Reply to
Harold & Susan Vordos

Either by induction hardening or flame hardening. Different methods to do the same thing. Get a thin layer of the surface very hot and let the bulk of the metal cool it down very quickly. After this treatment, 10-20 thou is normally ground off to eliminate distortions. Cast iron responds very well to this sort of treatment.

Mark Rand RTFM

Reply to
Mark Rand

Right you are, Mark...Induction heating is the chosen method when proper (modern) equipment is available. By choosing a relatively high frequency ( as opposed to when melting, where lower frequency is better suited) the surface alone can be rapidly heated. I'm not sure they don't quench after heating, but grinding is always a follow up due to distortion from the heating and cooling process.

Harold

Reply to
Harold & Susan Vordos

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