[srimanishreddy]

My question deals with a project replacing a cast iron housing (EN-GJL 250) with aluminium cast (EN-AC-AlSi7Mg0.3 ST6) housing. I am calculating the fit geometries for the new material housing based on its material thermal expansion properties. The housing has extreme temparature working conditions scaling from -40 to 110 deg Celcilus. From DIN 1706, I could find the mean thermal co-efficient value for the mentioned material from 20 to 100 deg C, but couldnot find the values for 110 and -40 deg Celcius. Any know-how to share regarding these values or topic would be a great help.

ideas on when a linear and cubic thermal expansion co-efficient should be used to calculate the fit geometries would be great.

thanks,
Enakonda

[peteeng]

Hi Enak - Generally speaking you use the linear expansion coefficient. If the object is long and thin especially. If its a "block" that has fits all round then use the volume coefficient. Sounds like you should use the volume figure. Interesting problem to solve as the CI and AL have quite different coefficients. CI is about 10 and AL is about 24-26....Peter

[machinehop5]

Any know-how to share regarding these values or topic would be a great help.

ideas on when a linear and cubic thermal expansion co-efficient should be used to calculate the fit geometries would be great.

Call Northrop engineering Dept. ask for Jack