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Posts Tagged ‘Rheological Data’

Rheological Data can Help to have a Better Metal Injection Molding Process

Posted on: March 29th, 2019

Azadeh Farahanchi, Rheological Scientist, Ph.D

Dynisco Polymer Evaluation Blog

How Rheological Data from a Capillary Rheometer Can Help to Have a Better Metal Injection Molding (MIM) Process?

Metal injection molding (MIM) is an advanced metalworking process to produce parts with complex shapes and high tolerances from a mixture of polymeric binder and metal particles/powders at specific volume ratios (feedstock). The flexibility and mass production of injection molding process makes it to be a great replacement to the traditional metallurgy process and therefore, MIM has been growingly performed in industry for large-number production of metal parts.

One of the key factors in any MIM process is the flow behavior of the feedstock during filling of of the mold. In order to have a defect free molding process (without jetting, short shot, sink mark, crack, etc.) with desired mechanical strength (tensile, flexural, failure stress, etc.) in the final products, understanding of the rheological properties of the binder and feedstock is necessary. The rheological analysis also helps to have defect free debinding and sintering procedures which are the final steps in a MIM process and gives the required mechanical strength to the final products.

In terms of rheological properties, there are three main factors which have significant effect on a MIM process namely, viscosity at the processing shear rate, thermal sensitivity, and shear thinning behavior of the feedstock. All these factors can be analyzed using a capillary rheometer. Since this rheological characterization method provide a wide range of shear rate, it is the best approach to study feedstock melt behavior in an injection molding process.