×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Shrinkage in Large ductile iron casting
2

Shrinkage in Large ductile iron casting

Shrinkage in Large ductile iron casting

(OP)
Dear all,

I have a large ductile iron casting ~250lbs with a wall thickness of 1 inch in resin bonded sand.
I got shrinkage issues that I can't seem to get rid off.

Chemistry :
C: 3.82
Si: 2.65
Mn .449
S 0.0108
Cu 0.0765
Mg 0.0319
Cr 0.0262

Pour Temp is 2590F.

Nodularity is great.

Any ideas?

RE: Shrinkage in Large ductile iron casting

250 lbs and 1inch wall thickness cannot be classified as heavy section castings. The C.E of the D.I casting is 4.7,you may reduce the C.E to 4.3 -4.4 . Also the pouring temperature is 1421C, you may reduce the C.E to 1390-1400C or lower. Also if the shrinkage is in thick section of the casting, you may provide chills . I hope the resin sand mold is rigid enough to withstand the graphitization pressure during solidification.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

RE: Shrinkage in Large ductile iron casting

(OP)
Arunmao,

I actually tried increasing the C to improve the expansion. That didn't work.
And then I tried to increase pouring T, reduce pouring t to fill it fast before graphitization starts.
I also tried pouring it slow... that didn't work either.
The casting is a pipe and there is shrink along the parting line. Looks more like interdendritic rather than large cavities.

RE: Shrinkage in Large ductile iron casting

Did you consider pouring the pipe vertically? Simple and uniform shapes are more challenging ?

You have tried increasing C.E ,which only increases expansion pressure. I hope the molds are rigid, and that there is no mold swell.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

RE: Shrinkage in Large ductile iron casting

(OP)
Actually I was thinking of the same thing. That way solidification may be somewhat directional.

It may be hard to keep the mold together though as it is impossible to move the parting line. So I am not sure.. probably I d need to strap it.

I also thought of using a copper pipe inside the core to act as a chiller..?

RE: Shrinkage in Large ductile iron casting

Ue a hollow core with zircon sand and let the core be made of inorganic binder. It will produce a good chilling effect. A resin core and mold generate heat delaying skin formation on the casting.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources