Austentic cast iron risering techniques? 1

[Tklfserve]

Looking for infomation on the finer pionts of risering Austentic cast iron, what riser/neck/casting modulus values are used to achieve general purpose soundness?
Does it have a more pronounce secondary shrinkage phase?
What ingate speeds have you found works well in practice?

 

[arunmrao]

Is it grey or ductile iron? You can check under Ni Resist D1 or D2 type cast irons .

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[Tklfserve]

Yes, it is Austentic cast iron types 20-2, 30-3, and 15-6-2
any risering infomation could be useful

thanks

 

[arunmrao]

Gating and Risering by S I Karsay has some recommendations . also I remember seeing some publications in Trans AFS on this topic.

I would go about using the same procedures as used in steel castings. Using the modulus method ,arrive at the riser dimensions. Do not calculate for feed metal requirements ,place exothermic sleeves,(preferably those with breaker cores). Use good quality filters in the runners to entrap any slag .

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[Tklfserve]

Thanks, i do already have a selection of Gating and Risering books by S I Karsay i'll see what i can do to try and look up AFS technicial support.
i agree with the use of filters have had many a good result from useing these.
i've just moved into this postion 2 weeks ago and a lot of the existing methods are based on the old 'pressurized runner bar ratios i.e. 1:2:0.5 but as you can imangine there is issues with reoxidation of metal due to extreme ingate speeds...
i need to do some work with filter max. mm/kgs before going the whole distance some of castings in 900 kg to 1600 kg wieght range
do you have any existing capacity figures for austentics?
i imange the chrome oxide formation will reduce capacities a bit?
thanks JM

 

[arunmrao]

The fluidity of this alloy is good and use of filter will not restrict the flow of liquid metal. What is the casting you plan to process in this alloy? Use non pressurised gating systems perhaps with multiple pouring or gating system if rapid filling of the mold is of concern due to thin section or recesses.

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[Tklfserve]

Pump housings or casings: the modulus lies between 0.9cm to 2.6cm typically. often called up in 250Mpa cast iron, 450-12 SGI, and then depending on application some austentics.

at moment gating is at partline and metal drops about 400-500mm to bottom - this is something I want to change to bottom gateing but this could be arkward unless dropping through existing coreing.

I do both, allow for appropriate modulus Mc/Mn/Mf ratio's [that's what i'm trying to find out] and allowance for feed metal usually 4%.

do you use blind or open exothermics? I would tend to prefer blind.
we have 100x100 sedex filters available. have thought about construcing a filterbank to get capacity.