Most molding defects blamed on the machine start in the material. Four habits keep hygroscopic resins honest before they reach the screw.
Dry to the resin, not to the routine
Every hygroscopic resin has its own drying window — temperature, residence time and target moisture. Running yesterday’s dryer settings on today’s material is how splay appears on a Monday. Post the drying card for the materials in the hall and set the dryer from the card, not from memory.
Watch dewpoint, not just temperature
A dryer can hold its temperature perfectly and still deliver wet air if the desiccant is exhausted. Dewpoint is the number that says the air can actually pull moisture; check it at the start of quality-critical runs, and log it so drift shows up as a trend rather than a surprise.
Respect residence time
Doubling the temperature does not halve the drying time — it risks the resin instead. If the hopper empties faster than the material dries, the answer is a bigger hopper or an earlier start, never a hotter shortcut. Size the hopper so the last pellet in has been drying for the full prescribed time.
Protect dried material on the way to the throat
Dried resin picks moisture back up in minutes in open containers and leaky conveying lines. Keep conveying runs short and sealed, purge lines at material changes, and never park dried material in an open bin waiting for the press.
