Density variation effecting balancing of cast iron machined parts 1

[MonsterShop]

We are manufacturing ductle iron ring gears which call for balancing when produced from castings with unmachined surfaces left on finished part. Due to a quantity reduction we are using cast iron bar and machining the part "all over". Would the balancing requirment be eliminated or could the variation in the density of the material be so bad that they still need it.

Some "pratical" advise would be greatly appreciated.

Thank you very much.

 

[MintJulep]

If it needs to be balanced it needs to be balanced.

 

[unclesyd]

We have not seen any variation in the quality of a good quality CI iron bar. We machined countless components for relatively high speed machines with no problem with balance. On some eccentric parts where we used small cuts to reduce the imbalance there was not enough imbalance between parts to worry apart. In other word we would machine the same slot on every part and not have worry about balance.

Here is one of the CI bars that we used.

http://www.dura-bar.com/

 

[sreid]

It depends on the degree of balance required. Can you tell us what that is?

 

[MonsterShop]

Ill find out and repost it on Monday.

Thanks for your input.

 

[arunmrao]

For any cast parts ,balancing needs are more pronounced than for forged or machined parts.

In the case of ductile iron,if as cast surfaces remain,they could be influenced by variations in density(due to micro porosity/shrinkage) or due to mold wall movement while the casting solidifies. Mold wall movement(resulting in bulge) is absent in case of steels and grey irons.

To avoid or minimize the problem it is best to machine all over.(if design permits).

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