In-Mold Rheology Test…

I received this question via email last week…

I am new to plastics technology and am looking for input on how to do an in-mold rheology test.

My Response
Although there is much training centered around the in-mold rheology curve, the basics are as follows:
  • Fill the mold as fast as you can with a short shot during 1st stage velocity controlled injection
  • Record the fill time and injection pressure at transfer
  • Repeat this process using incrementally slower speeds
  • Use 1/(fill time) for apparent Shear Rate
  • Use (Pressure)*(Fill Time) for Relative Viscosity
  • Graph Relative Viscosity (X axis) vs. Shear Rate (Y axis)
Additional Thoughts
For more posts about rheology, just type rheology in the search box in the upper right hand corner of this page.

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