Diamond Systems Tritan Guia de Resolução de Problemas descarregar pdf (Página 39)

Suggested remedies

Do 1 ﬁrst, 2, 3, etc.

1 means increase

2 means decrease

PROBLEMS

Short

shots

Brittle

parts

Voids

sinks

Bubbles

Surface

splay

Gate

splay

Sprue

sticking

Part

sticking Burning Flash

Brown

streaks Discoloration

Black

specks

Weld

lines Jetting Warpage

DRYING

Make sure polymer is dry 1 11 1 5 12 7 10 42

TEMPERATURES

Melt temp 61 22 71 46 66 132 72 32 66 11 31

Mold temp 71 96 32 82 71 16

Nozzle or hot runner 81 52 22 22 62 41 4+

Decrease sprue temp 5

Reduce ∆T (barrel, nozzle,

HR) 6

PRESSURES

Injection pressure 21 102 31 42 82 42 12 31 26 72

Back pressure 91 62 81 11 76 111 82 46

Clamp pressure 31

TIMES

Mold closed/cooling 42 62 96 26

Injection hold 51 21 92 52 42 51 8

Booster time 31 51 102 62 22 41 9

Reduce overall cycle 42 122 10 92

OTHER

Injection speed 41 62 22 12 42 22 52 61 16 32

Screw speed 52 101 46 102 72 5

Decompression/suckback 22 32 32 5

Use sprue break 7

Cushion size 11 11 3

Ejection uniformity 8 5

Purge barrel

6 8 3 3 1 1

Reduce regrind % 7 12 8 11 9 5 3

Check for voids 8

Check for contamination 3 7 9 4 2 2

HARDWARE

Eliminate sharp corners 14

Check sprue/nozzle diam 5 1 4 10

Incr. gate size/streamline 101 131 111 71 51

Change gate location 14 9 6 12 9 6 11

Vent size/cleaning/location 111 11 62 21

Add overﬂow @ weld area 8

Use different size machine 121 92 13 131 11

Repair Mold 13 10 15 13 11

Increase taper/draft angle 14 12 10

Check for undercuts 3 12 62

Check puller design 2 2

Fix defective check ring 1 12 7

Add pin, etc., to impinge ﬂow 7

Troubleshooting guide: Molding Eastman

™

polymers

General • Dry at 27°C (20°F) or lower dew point. • Use full round runners.

guidelines: • Dry for 6 hours. • Use nozzle diameter greater than 4.8 mm (3/

in.).

• Use 0.06 m

/min dry air per kg/h (1 ft

/min dry air per lb/h) of resin used. • Use short nozzle or nozzle with uniform heat control.

• Refer to data sheet for correct drying temperature. • Use moderate back pressure, usually 0.34–1.38 MPa (50–200 psi).

• Use multidesiccant bed dryer (vs. tray or batch dryer). • Use slow to moderate screw speeds.

• Select machine size to use 40%–75% of capacity. • Gate into thickest area of part with gate 50%–75% of part thickness.

• Use sliding check ring with no holdup spots rather than ball check. • Vent mold 0.0245–0.0305 mm (0.0001–0.0012 in.).

Voids typically have no foamy tail where air/gas bubbles often have a tail or trail.

Purge with commercial purge compounds, acrylic, styrene; polyethylene and polypropylene are not usually good purge materials for these polymers.

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