Draw Down Ratios

Along with modifying polymer properties, choosing the appropriate draw down ratio is also vital to process stability. MedEx Engineering could help your company find the correct solution to a particular problem of inconsistent tubing dimensions.

Here is an example:

Material: Polyether Block Amide

OD x ID: 0.060″ x 0.050″

Problem: Could not hold better than +/-0.001″ on the wall thickness due to the inconsistency of the polymer composition (excessive gels).

How MedEx Engineering solved the problem:

We increased the draw down ratio along with the draw ratio balance. With the DRB increase we were able to decrease the shear in the die, which decreased the amount of gels present in the extrudate. Ultimately we are now holding better than +/-0.0003″ on the wall thickness.

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