Page 395 - Injection Molding Advanced Troubleshooting Guide
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40.3 Short Shot Troubleshooting  393






































          Figure 40.10  Example of nozzle to sprue leak




          40.3.4„ Short Shot Troubleshooting Material Issues


          The material can cause short shots due to several issues including:
             ƒ Viscosity shift
             ƒ Moisture content
             ƒ Inconsistent material feed
             ƒ Unmelts
             ƒ Contamination

          40.3.4.1„ Material: Viscosity Shift

          Viscosity is a measure of the resistance of a material to flow. As viscosity increases
          the material will not flow as easily. If material viscosity increases two main con-
          cerns will arise:
          1. High viscosity material may not flow into difficult to fill areas of the mold.
          2. Higher viscosity will lead to increased pressure drop across the mold resulting
            in lower cavity pressure at end of fill locations.
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