High Lead Bronze - Sand and Centrfugal Casting

[tricecold]

We are a bronze foundry located at Turkey Kocaeli.

We have been having trouble casting of High Lead bronze in both centrifugal and sand casting, even thou we try to cool the casting with high pressure water and etc, no matter what we do in sand casting inside diameters we have lead sweating prematurely casuing defects.

However on centrifugal casting we have problem on the outside diameter lead building up like a 2 mm shell. If anyone here is experienced such an issue, please advice on casting temperature or application of lead to the furnace or other things you might think of. Thanks in advance..

 

[arunmrao]

As lead does not go into solution it remains liquid for a long time(till its freezing point (about 615F). Do not have a hot shake out of the casting. allow the castings to cool in the molds. Use chills where ever possible to increase the solidification rate. Also try to pour at as low a temperature possible. Thoroughly degas the metal before pouring.

These are some commonly known tips to avoid the problem of sweating.

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)

 

[tricecold]

Well i am going to cast these pieces tomorrow and i will post the results along with my proceudre with photos. Forgive my english but by saying hot shake do you mean cool it but dont remove it from the mold as long as possible?

 

[arunmrao]

Yes allow the castings to remain in the mold for as long a time as possible.

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)

 

[arunmrao]

Can you get this classical text book . You can get a better insight into your problem

Non-Ferrous Foundry Metallurgy - The Science of Melting and Casting Non-Ferrous Metals and Alloys (Hardcover)
by Alfred John Murphy (Author)

Product details
Hardcover: 497 pages
Publisher: Pergamon Press, London (1954)
Language English
ASIN: B0000CIRG8


Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)

 

[Tklfserve]

Double check your nickel content 1-2% is about a good min. aim it'll held keep the lead in suspension.
we had a case the other day where the lead was about 2% lower than the bottom of a 400mm casting just from the gravity effects it allways tends to settle to the bottom. chilling and homogenizing by mixing or metallurgy are good paths to try.

 

[arunmrao]

If the problem is of gravity segregation,then one can reverse the mold,after a short time interval.

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)