Page 91 - Injection Molding Advanced Troubleshooting Guide
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8.6 Velocity to Pressure Transfer 75
Figure 8.14 Velocity to pressure response on electric press. Each of the three curves has
three cycles and the quickest response on the curves was with the fastest hold
velocity setting.
8.6.1 Machine Control
Injection molders should be in the habit of verifying if the machine is “doing what
we ask, when we ask.” Do not assume that because a value was set on a controller
that the machine is actually achieving the value. Machines can become out of cali-
bration on a wide number of crucial settings. If the machine is not achieving the
desired setpoint the result can be a wide range of defects.
With the wide variety of machine controllers, it is a challenge to have every proces-
sor in the shop understand how each controller performs. Controllers will have a
variety of process settings to achieve the same results. For example, first stage may
be called fill, boost, injection, or velocity and may have units of in/sec, mm/sec,
cm/sec, in /sec, cm /sec, or %. Figure 8.15 shows a variety of machine controllers;
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does everyone who uses the various controllers know how to use them?
