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15.3 Black Specks Troubleshooting 137
system may be required when experiencing ongoing black speck problems. Check
for mismatch, excess wear, and damage because often times if any of these are the
root cause there will be a buildup of blackened material trapped in these areas.
Replacement of the component is the likely solution to the problem.
15.3.3.2 Machine: Barrel Heater Control
A machine must be in control of the barrel heaters to ensure that there are no loca-
tions of overheating in a barrel or nozzle. Verify that there are no hot spots on the
barrel or nozzle; a good method to check this is by using an IR thermal imaging
camera (see Figure 15.4). Note that black specks are usually a later state of degra-
dation; brown streaks and splay may be an early indicator of problems.
Figure 15.4 Infrared photo of nozzle
15.3.3.3 Machine: Machine Performance
The machine must be running at the established set points. See Chapter 8 on ma-
chine performance for more information.
15.3.4 Black Specks Troubleshooting Material Issues
Potential material related concerns are as follows:
Contamination
Wrong material
Regrind fines
