TRANS. TRANS. TRANS BLUE S-218-1

GREEN AQUA TRANS MAGENTA TRANS 2 PEACH TRANS

TRANS DK PINK 1777C ACY VY TRANS PINK 1767C ACY V2 TRANS BLUE ACY 283 V2

TRANS. GEON EXP CP 15502112906 TRANS 9000 DB4106 TRANS RED

TRANS GREEN PETG TRANS BLUE PETG TRANS PINK PETG

MC-34209PC TRANS. MC-34231AC TRANS RED LENS MC-34448ST TRANS RED

PS TRANS AMBER V2 TRANS RED-FD TRANS BLUE-FD

TRANS PURPLE PEARL #2 TRANS RED CD4989 PINK 191 TRANS MET

DEFECTS Design Guide 33 SOURCES Mold Machine Material Process Mold damages Loss of clamp force Barrel malfunction Contamination Wet material Melt temperature too high Injection speed too high Transfer position too low Excessive pack pressure Excessive back pressure RECOMMENDED ADJUSTMENTS Repair mold damage Clean parting line Reduce pinch-off land Increase clamp force Dry material Reduce melt temperature Reduce mold temperature Reduce injection speed Reduce hold pressure Increase transfer position Flash • Excess material commonly found at parting lines or mold features Root cause: Too much plastic or mold damage. 34 Gravi-Tech SOURCES Mold Machine Material Process Design of gate too small or in wrong location Machine not providing requested velocity Heater overriding Wet material Viscosity too low Injection velocity too high Melt temperature too high Mold too cold RECOMMENDED ADJUSTMENTS Increase gate size Remove sharp corners from gate detail Change gate type Move gate to a position where the melt stream will impinge upon a mold feature Dry material Reduce injection velocity Increase melt temperature Jetting Root cause: Injection speed is too high for the viscosity of the material DEFECTS Design Guide 35 SOURCES Mold Machine Material Process Finish too rough Venting impaired Screw configuration Overworking material Non-compatible additive Melt temperature too high Back pressure too high Injection speed too fast Mold too cold RECOMMENDED ADJUSTMENTS Remove sharp corners from gate detail Insure proper venting Increase gate size Use smaller screw/barrel Check melt uniformity Check L/D ratio Dry material Check additive compatibility Reduce melt temperature Reduce screw speed Reduce back pressure Reduce residence time Reduce injection speed Plate-Out • Build-up or deposit on mold surface Root cause: One component of the material is not totally compatible. 36 Gravi-Tech SOURCES Mold Machine Material Process Venting impaired Shut-off partially turned Screw problems Barrel heater problems New lot Contamination Material too dry Under-packing Injection speed too low Not enough pack pressure Melt temperature too low Transfer position too high RECOMMENDED ADJUSTMENTS Make sure gate is not blocked Insure runner shut-off is not turned Check venting Increase gate size Change gating location Add flow leader Insure cushion position Make sure screw is trans- ferring at a correct position Change screw/barrel Make sure material was dried at proper settings Increase melt temperature Increase mold temperature Increase injection speed Decrease transfer position Short Shot • Not enough material is being injected into the mold to fill out all of the cavities Root cause: Not enough plastic is getting into the cavity. DEFECTS Design Guide 41 SOURCES Mold Machine Material Process Hot spots Improper cooling Impaired venting Heater band overriding Leaking check ring Contamination New lot No cushion Hold pressure too low Melt temperature too high Reduce transfer position Back pressure too low RECOMMENDED ADJUSTMENTS Check gate for blockages Check runner shutoffs Increase gate size Add a flow leader Ensure cushion is maintained Make sure screw is trans- ferring at correct position Dry material Increase/decrease melt temperature Increase mold temperature Reduce injection speed Increase hold pressure Increase hold time Voids • Usually occurs in a thick section where the melt remains hotter than the rest of the part.

TRANS ORANGE CD5176 TRANS YELLOW TRANS ORANGE CD5175