https://www.avient.com/sites/default/files/2020-10/2020-gravi-tech-design-guide-.pdf
Edge Gate
This is the most common manual trim gate.
Sprue Gate
The sprue is gated directly into the part.
Tunnel Gate
A tunnel gate is the most common automatic
gate, and is a tapered gate that intersects the
part below the parting line.
https://www.avient.com/sites/default/files/2020-10/2020-gravi-tech-processing-guide.pdf
Increase gate size or number of gates
Moisture 1.
Increase gate size
3.
Increase gate size
Blush
Injection too quickly
through gate
1.
https://www.avient.com/sites/default/files/2020-09/surround-processing-guide-2020.pdf
TEMPERATURE
Material Rear
Center
Front
Nozzle
Melt
Mold
Nylon 6,6
540–570
530–560
530–560
540–570
540–570
200–300
(90–150)
Nylon 6,6
30% SS
540–570
530–560
530–560
540–570
540–570
200–300
(90–150)
PBT
510–410
(265–280)
490–540
(255–280)
480–530
480–530
480–530
150–250
(65–120)
PC
14% NiCF
540–570
540–570
530–560
530–560
530–560
150–250
(65–120)
ABS
470–520
460–520
460–520
460–530
(240–275)
460–530
(240–275)
100–200
(40–90)
PP
440–480
(225–250)
440–480
(225–250)
430–470
(220–245)
420–460
(215–240)
420–460
(215–240)
125–175
(50–80)
DRYING
Material Temperature
°F (°C) Time Minimum
Moisture
Maximum
Moisture
Nylon 6,6
14% NiCF 180 (80) 4–5 hours 0.05% 0.20%
Nylon 6,6
30% SS 180 (80) 4–5 hours 0.05% 0.20%
PBT
14% NiCF 250 (120) 6-8 hours 0.02% 0.03%
PC
14% NiCF 250 (120) 3–4 hours 0.02% 0.02%
ABS
14% NiCF 200 (90) 2–4 hours 0.05% 0.10%
PP
14% NiCF 180 (80) 2–4 hours 0.20% 0.30%
Equipment
• Feed throats smaller than 2.5" may cause bridging due to pellet size
- Larger feed throats will be more advantageous with long fiber EMI shielding resins
• General purpose metering screw is recommended
- Mixing/barrier screws are not recommended
• L/D ratio
- 18:1–20:1 (40% feed, 40% transition, 20% metering)
• Low compression ratio
- 2:1–3:1
• Deep flights recommended
- Metering zone 3.5 mm
- Feed zone 7.5 mm
• Check ring
- Three-piece, free-flowing check ring
• General purpose nozzle (large nozzle tips are recommended)
- Minimum orifice diameter of 7/32"
- Tapered nozzles are not recommended for long fiber EMI shielding resins
• Clamp tonnage:
- 2.5–5 tons/in2
Gates
• Large, free-flow gating recommended
- 0.25" x 0.125" land length
- 0.5" gate depth
Runners
• Full round gate design
• No sharp corners
• Minimum of 0.25" diameter
• Hot runners can be used
PROCESSING
Screw Speed Slower screw speeds are recommended to protect fiber length
Back Pressure Lower back pressure is recommended to protect fiber length
Pack Pressure 60–80% of max injection pressure
Hold Pressure 40–60% of max injection pressure
Cool Time 10–30 seconds (depends on part geometry and dimensional stability)
PROCESS CONSIDERATIONS
Recommended – retain fiber length (maximize conductivity)
• Low shear process
• Low screw speed and screw RPM
• Slow Injection speed
• Fill to 99–100% on first stage of injection
- Reduces potential nesting of fibers at gate location
- Improves mechanical performance near gate location
- Promotes ideal fiber orientation
Resin Rich Surface
• Achieved when using a hot mold temperature and longer cure times
≥ Max mold temperature recommendation
• Improved surface aesthetic
• Reduced surface conductivity
• Could reduce attenuation performance in an assembly
Fiber Rich Surface
• Achieved when using a cold mold temperature and shorter cure times
≤ Minimum mold temperature recommendation
• Improved surface aesthetic
• Reduced surface conductivity
• Could improve attenuation performance in an assembly
www.avient.com
Copyright © 2020, Avient Corporation.
https://www.avient.com/sites/default/files/2023-11/Cesa Clean Processing Usage Guide.pdf
VALVE-GATED TOOLS IN
INJECTION MOLDING GUIDELINES
CESA
CLEAN ADDITIVES
™
KEY FEATURES
Cesa™ Clean Additives
• Cesa Clean is a concentrated purge product, not a purge compound.
• It can be processed through manifolds, valve-gated tools and small sub gates.
• Cesa Clean is 100% recyclable with polyolefin resins and compounds.
GUIDELINES FOR USING CESA CLEAN ADDITIVES
• Cesa Clean works best when molded maintaining normal (injection)
pressure/shear
• For best results, Avient recommends a “Running Color Change”
which eliminates breaks in the molding cycle
• Since the Cesa Clean concentrate will expand, it is recommended
to reduce the shot size by 20%
• It is designed for use at a let-down ratio (LDR) of 3.0% or (33:1); however,
use rate can vary depending on the severity of the contamination but
typically is 2.0–4.0% (a use rate higher than 6.0% may not have any
positive affect on the cleaning performance)
• Using Cesa Clean as a routine part of your color change rotation will
allow faster changes and consume a minimal amount of raw material
- Note: If the manifold is not cleaned routinely, this process may be
more time consuming and additional material will be required
• It is best to process at your normal polymer processing temperatures
- For best performance, stock temperature should be at least 400°F
- If 400°F is achieved during the purging process, no additional
activation will occur during the reprocessing of regrind
- All parts produced during the “Running Purge Cycle” should be
captured as regrind, resulting in a scrap-free color change
- If using sequential gates, open and close all gates at the same time
while purging the tool
- If contamination appears to be coming from one gate, open and
close first, and for an extended period of time, to force more material
through this location
- When cleaning in this manner, pay close attention to shot size
- Parts containing the previous or new color plus any Cesa Clean
can be used as regrind
INTRODUCING CESA CLEAN TO YOUR PROCESS
Hand Blend
• Hand weigh enough of the Cesa Clean and
natural resin mix to equate to 3–5 times the
barrel capacity
• Use rate should be 3.0% or 33:1 for routine
cleaning
• For difficult-to-clean tooling, or tooling which
is not routinely cleaned, start at 4.0% or 25:1
• Note: Do not attempt to vacuum load more than
15 feet from source as stratification/separation
may occur
Volumetric Feeder
• Calibrate feeder to dispense 3.0% or 33:1 for
routine cleaning
• For difficult-to-clean tooling, or tooling which
is not routinely cleaned, start at 4.0% or 25:1
• This style of feeder is highly recommended for
at-the-throat metering of Cesa Clean
Blending Units
Most blenders have an extra bin for an additive
• Fill the additive bin with Cesa Clean
• Set blender to introduce the Cesa Clean at
2.0 to 4.0%
• Note: Do not air convey any further than 15 feet
as Cesa Clean has a high density and may separate
from the mix.
https://www.avient.com/sites/default/files/2020-09/stat-tech-tri-fold-processing-guide.pdf
MOLD DESIGN RECOMMENDATIONS
Gates
• Many different types of gates can be used such as pin, fan, tunnel, tab and edge gates.
Gate type
should be selected based on location and part geometry
Gate diameters equivalent to 50%–75% of the average wall thickness are recommended
https://www.avient.com/sites/default/files/2020-12/therma-tech-processing-guide.pdf
Mold Design Recommendations
Gates
1.
Many different types of gates can be used such as pin, fan, tunnel, tab
and edge gates.
Avoid placing gates in thin regions of the part.
https://www.avient.com/sites/default/files/2022-06/Nymax BIO Bio-based Polyamide Solutions Processing Guide.pdf
All types of gates can be used such as pin, fan, tunnel, tab and edge gates.
Enlarge gates and/or runners
5.
Increase gate size
2.
https://www.avient.com/sites/default/files/2022-06/Maxxam FR Injection Molding Processing Guide.pdf
Additional draft may be required for
grained/textured surfaces
Gates
• All types of gates can be used such as pin, fan, tunnel, tab and edge gates.
Gate type should be selected based on location and part geometry
Gate diameters should be equivalent to 50–80% of the average wall thickness
• A land length of 0.040" (1.0 mm) is recommended
• Valve gates can be a source of extreme shear for halogen-based systems.
https://www.avient.com/content/compl-t-and-onforce-molding-guidelines-and-processing-conditions
Gates
https://www.avient.com/knowledge-base/article/emerging-trends-and-top-10-production-challenges-blow-molded-bottles
Flow Lines: near gate points, compromise appearance and aesthetics