This equation from the Injection molding handboook(Rosato) 1

[Kes]

I came across this equation in the "Injection Molding Handbook (written by Dominic and Donald Rosato)" and its really important I find out what it means. It is located on pg.196 of the 1986 edition of the book the equation is:


S= (-t^2/2pi*a)*ln(pi(Tx -Tm)/4(Tc -Tm))
where: S= minimum cooling time (sec)
t= thickness of molding (in. or cm)
a= thermal diffusivity of material (inc^2/sec)
Tx= ejection temperature of molding(distortion temperature)
Tm= mold temperature
Tc= cylinder temperature


I am trying to find out if this equation means that this is the minimum time required for air cooling or is this for all possible cooling procedures. To elaborate, I want to know if this equation is to only for air cooling or is it the total cooling time possible (no matter how much what procedure is used including cooling channels etc...)

 

[dhuffy]

Kes,

The equation is for the injection molding process if you want to calculate the minimum ESTIMATED cooling time for a given part. From the equation, you can see it is asking for the thickness of the part you are molding, the material properties and for information about the process (mold temp). This is not for air cooling, but rather cooling based on the injection process.

Dave