Questions regarding machinig Austempered Ductile Iron, Pre and Post Austemper.
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    Default Questions regarding machinig Austempered Ductile Iron, Pre and Post Austemper.

    I have not worked with much cast iron and/or ductile iron for several years. Made glands and pistons for hydraulic cylinders mainly. That being said I'm starting work on a new prototype project, proto will start life as 6X6 piece of bar roughly 12.5" long for now(future iterations will likely be cast). Starting material will be Ductile Iron 65-45-12, machine will likely be my TM1-P as I'd rather contaminate 10 gallons of coolant than 100. Normally run cast dry but from what little I've found to read about ADI using coolant can gain considerable tool life and surface finish.Final product is spec'd to be Austempered Ductile Iron of 125-80-10.

    On to the questions; I am to rough this part out pre HT which from what I've researched the material will expand 0.2-0.4%. Ideally how much should I leave on here to finish afterwards? Another issue I have, some of these drilled and tapped holes have positional tolerances of +/-.002, therefore I'm thinking I will not be able punch any of the holes through until after HT. Anyone have any experience with such material that could offer any preferred practices and tooling choices would be greatly appreciated.

    Thank you in advance, John.
    Last edited by Machinist John; 11-15-2018 at 08:03 AM.

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    I'm too stupid to help. I've little idea what "Austentising" means exactly.

    Either way, if it's going to move X during the process, I would leave X+ for finishing.

    R

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    First thing I'd suggest is scaling your CAD by whatever volumetric shrinkage you anticipate. This method is more sound in my mind than simply leaving a large stock allowance all around your part.

    After scaling, I'd be tempted to leave as much stock on the part as heat treatment will allow (dictated by the quench). It's a large part and could move unpredictably depending on orientation during quench and quench bath convection.

    I'd want to see a few mm of stock given that this is the first time you are trying this.

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    Register, thank you for that idea. That may be just the ticket as long as the expansion is as linear as I've read. And Rob I've read thousands of posts on here and stupid is not a term I would apply to anything you've said. One of the great joys of this trade for me is the constant learning we all are lucky enough to do day in and day out. It's all a learning experience. I have been able to find a littler more information here. Ductile Iron Data - Section 4
    I was just hoping to pry some practical experience from some of ya'll that may have dealt with the material before.

    Thank you for the responses! John

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