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06-16-2011, 06:39 AM #1
gray or ductile iron for machine base?
I've been tasked with making a shorter base for our climax portable mill. Climax doesn't have any in stock, but will sell us a used machine for $12k that has the short base. "Gee, Kerry, that looks pretty simple.Can't you just make one?"
I found a place that sells cast iron :
Rectangles / Squares Ductile
But what would be the best fit for my application?
06-16-2011, 06:44 AM #2
Ductile iron will absorb vibration better. If you hollow out the legs and fill them with sand it will absorb even more vibration.
06-16-2011, 06:49 AM #3
Make a wood mock-up and try it on a few repeat projects before you commit to a design.
Otherwise use DuraBar's G2. Strong, stable, easily machined, scrapes beautifully.
06-16-2011, 06:50 AM #4
I think gray iron is nicer if you plan on hand scraping it. But ductile is better in case you drop it. You did say portable, so I anticipate it could get dropped.
06-16-2011, 07:26 AM #5
I don't believe DI has better dampening effect over CI.
06-16-2011, 07:50 AM #6
06-16-2011, 07:53 AM #7
06-16-2011, 08:19 AM #8
ASTM A536 or 65-45-12 ductile.
06-16-2011, 08:23 AM #9
I agree with Forrest on a prototype.
Maybe an aluminum proto, and then if anyone has some changes or other input, you can do that to the final product.
Also, that Dura-bar that Forrest is talking about is sweet
06-16-2011, 04:41 PM #10
Is it really saving money over buying the used machine? I would give that decision a hard look to be sure all the costs of building or covered. Most times making something is much cheaper than making new if used is available. Head scratching over cast iron costs money if you are doing it on the job. What is the cost of down time building equipment compared to doing whatever brings in money rather than spending it?
06-17-2011, 01:27 AM #11
I'm going with ductile on this one. Impact resistance is something to consider.
Thanks to all
06-17-2011, 03:29 AM #12
I made one for the company I use to work for out of an old pcs. of A36 and it worked great for several years. I think any form of cast iron will work well for a portable aplication as the set-up are only ever temporary and the machines are seldome used for very long.
06-17-2011, 04:16 AM #13
good choice on the ductile as JR reccomended. I've considered making a longer track for my Versamil and searched a little bit. (Plus I have castings made and have considered the trade -offs for some other applications) Ductile does not scrape nearly as nicely as grey CI, and it is a little tougher to machine. But it has 50% - 80% better stiffness (lighter part for same section) and strenght. It also does not creep yield quite like CI does. Pearlitic ductile is eve stranger than A36/mild steel. Since the sliding components are most likely CI with adequate bearing quality, I'd choose the extra strength and hardness of Ductile if the price difference is not great.
Simplified, but you can google for more:
06-17-2011, 12:24 PM #14
Grey iron is the choice for damping. Engine blocks and heads are (were?) made from this material.
Nodular (ductile) is the choice for a stressed part like a steering knuckle or a crankshaft.
Nodular will ring like a bell whereas grey iron will crack/shatter with the appropriately sized blow.