Nylon 6 (PA 6)

(1) Barrel Temperature

Feed Zone:    60–90°C (70°C)

Zone 1:   230–240°C (240°C)

Zone 2:   230–240°C (240°C)

Zone 3:   240–250°C (250°C)

Zone 4:   240–250°C (250°C)

Zone 5:   240–250°C (250°C)

Nozzle:   230–240°C (250°C)

Temperatures in parentheses are recommended baseline settings at 35% and 65% stroke utilization, with flow length to wall thickness ratio between 50:1 and 100:1.

Temperatures in the feed zone and Zone 1 directly affect feeding efficiency; increasing these temperatures promotes more consistent feeding.

(2) Melt Temperature
240–250°C

(3) Barrel Residence Temperature
220°C

(4) Mold Temperature
60–100°C

(5) Injection Pressure
100–160 MPa (1000–1600 bar). For thin-wall long-flow-length products (e.g., cable ties), up to 180 MPa (1800 bar) may be required.

(6) Holding Pressure
Approx. 50% of injection pressure. Short holding time is sufficient due to relatively rapid material solidification. Reducing holding pressure minimizes internal stresses.

(7) Back Pressure
2–8 MPa (20–80 bar). Requires precise adjustment; excessively high back pressure can cause uneven plastication and degradation.

(8) Injection Speed
Relatively fast speeds are recommended. The mold must be well-vented to avoid burn marks.

(9) Screw Speed
Peripheral speed ≈ 1 m/s. Prefer lower screw speeds provided plastication completes before cooling ends. Low screw torque is required.

(10) Metering Stroke
(0.5–3.5)D

(11) Cushion
2–6 mm, depending on metering stroke and screw diameter.

(12) Pre-Drying
4 hours at 80°C (unless feeding directly from sealed container). Nylon is hygroscopic and must be stored in moisture-proof containers or closed hoppers. Moisture content >0.25% adversely affects processing.

(13) Regrind
Up to 10% regrind can be used.

(14) Shrinkage
0.7–2.0%. With 30% glass fiber: 0.3–0.8%. For mold temperatures >60°C, gradual cooling is recommended to reduce post-molding shrinkage, improving dimensional stability and minimizing internal stress. Steam cooling is suggested. Stress can be inspected using solvent testing.

(15) Gating System
Pin-point, submarine, edge, and direct sprue gates are suitable. Use cold slug wells and blind holes to capture cold slugs; hot runners are applicable. Due to the narrow processing window, closed-loop temperature control is essential for hot runners.

(16) Machine Shutdown
No purging material required. Melt can remain in barrel for up to 20 minutes before thermal degradation occurs.

(17) Barrel Equipment
Standard screw (special geometry available for higher plastication capacity), non-return valve, open nozzle. For glass-filled grades, wear-resistant bimetallic barrels are recommended.