Page 73 - Plastics News May 2024

IN THE NEWS

Speed should be set to create the best validation and mostly focus on adjust- munication. A dedication to process
quality, not satisfy an inverse rheologi- ments to pack and hold pressure. must be supported from the top down.
cal curve. Image courtesy of RJG Inc. If management creates a set of best
via Freudenberg Medical. Five common problems that can practices, but also encourages the
We have found that by adopting this be minimized through better pro- floor to do whatever it takes to produce
approach, it only takes about five cy- cess. a good part, operators will quickly skip
cles to correct metering, three to five Shot-to-shot inconsistency caused by process and revert to a “tinkering”
cycles to correct pressure, and five a bad metering phase. mindset.
to 10 cycles to correct the cushion It is important, however, that the pro-
in front of the injection screw. Fixing Dimensional changes due to variable cedures be revisited frequently. They
short shots should only take three to viscosity or pressure losses. are not a “set it and forget it” exercise.
five cycles…if you are focused! Variable weld lines because the ma- Communication must flow freely be-
chine is running full tilt. tween management, floor supervisors
Adjust. Measure. Refine. Repeat. Re-
member: Only change one variable at a Excess flash due to too much pressure and operators. Ongoing operator train-
time and document the results, not the in the parts. ing is absolutely critical and proce-
machine settings! dures need to be revisited on a regular
Shorts caused by a lack of pressure in basis to ensure they reflect current
Once the process is optimized, it can the parts. best practices. It’s the best way to tru-
be validated. The ultimate goal is to ly create a culture of consistent quality
adjust other variables — fill time, melt Creating a culture of consistency. through a stable process.
temperature, hold time, mold tempera- A good process is nothing but words
ture, cooling time — very little during on paper without teamwork and com- Source – Plastic Today

The Troubleshooter: Setting Up Your Injection Molding Process

for

Paying close attention to key setpoints in barrel and mold temperature, pressure, time, and cooling will help
eliminate defects and scrap.

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