Does this sound familiar…
“Don’t mess with the machine controls, we’re making good parts.”
Okay, but are you making good parts as inexpensively as possible? Is your molding cycle time as fast as possible? Are you using the minimum amount of material to make an in-spec part?
If you want molding cycle time improvement and maximum profits, these are the questions you should make sure your key production floor personnel are asking.
Here’s a quick checklist that you can use to make sure you are making as much profit as possible on a molding job.
- Check the plastic melt temperature. Record it and then reduce the melt temperature 20° F. Do this by lowering the front and middle barrel zone temperatures.
- Reduce the mold closed time about 5%. Check the parts. Look for added internal stress, and a change in directional shrinkage (anisotropy). If the parts are okay you’ve just reduced cycle time and increased production by 5%.
- One more point… When you are making good parts, the front barrel zone temperature should be reset to match the plastic melt temperature. Use a pyrometer to get an accurate reading. This is important. You want to neither heat nor cool the plastic at the front of the barrel. That would cause temperature differences in the plastic melt.
- If you are molding a crystalline plastic you may have to increase the front zone to get the temperature you need. But that’s okay because the viscosity of a crystalline plastic doesn’t change much after it is melted.