• Black Specks - plastic injection troubleshooter
| • Description:
Small black areas (spots) inside the material,
mostly present in transparent resins.
||· down time too long
· barrel switched off
over a long period
· poor purging of barrel
· dirty plasticizing unit
· inadequate nozzle
||· dead edges in gate/
||· granule impurities
· degradation by other resins
· pick-up of degraded
material from cylinder wall
||Purge with an appropriate material
in general, or with a universal purging compound like Kapronet.
For PC, you can useground acrylic or regrind PC resin;
for Ultem resin use regrind Ultem resin or glass-filled PC
resin, and so on.
Don’t drop temperature settings while purging.
||check for impurities: use uncontaminated material,
do proper housekeeping
||check and adjust melt temperature
||check for dead edges: nozzle, back flow valve,
||check for screw wear
contact : jmfalcao@webXpace.com