Typical Injection Molding Conditions English SI Metric
Temperatures
Rear Zone 420 – 450 °F 216 – 232 °C
Center Zone 410 – 440 °F 210 – 227 °C
Front Zone 400 – 430 °F 204 – 221 °C
Melt 410 – 480 °F 210 – 249 °C
Mold 100 – 170 °F 38 – 77 °C
Pressures
Injection 10000 – 15000 psi 69 – 103 MPa
Hold 5000 – 10000 psi 34 – 69 MPa
Back 25 – 50 psi 0.17 – 0.34 MPa
Speeds
Fill 0.5 – 1 in/sec 13 – 25 mm/sec
Screw 30 – 70 rpm 30 – 70 rpm
Drying
Time & Temperature 2 Hrs @ 175 °F 2 Hrs @ 79 °C
Dew Point -20 °F -29 °C
Moisture Content 0.10 % 0.10 %

  • To maximize fiber length, the following injection barrel, screw, and tip designs should be followed: 1.) L/D ratio 16/1 to 22/1. 2.) Compression ratio 2:1. 3.) Flight depth 0.20 in. (5.08 mm) minimum, in feed section. 4.) Screw diameter 0.65 to 0.80 in. (16.51 to 20.32 mm) minimum. 5.) compression section length 12 to 13 diameters. 6.) Check ring valve assembly – free flow type no restrictions. 7.) Nozzle orifice 0.25 in (6.35 mm) diameter.

  • Feed throat from hopper to machine must have sufficient opening to prevent bridging of long pellet composition.

  • Uses a reverse barrel profile to ‘presoak’ or ‘soften fibers.’

  • This information is intended to be used only as a guideline for designers and processors of modified thermoplastics for injection molding. Because injection mold design and processing is complex, a set solution will not solve all problems. Observation on a “trial and error” basis may be required to achieve desired results.

  • No information supplied by RTP Company constitutes a warranty regarding product performance or use. Any information regarding performance or use is only offered as suggestion for investigation for use, based upon RTP Company or other customer experience. RTP Company makes no warranties, expressed or implied, concerning the suitability or fitness of any of its products for any particular purpose. It is the responsibility of the customer to determine that the product is safe, lawful and technically suitable for the intended use. The disclosure of information herein is not a license to operate under, or a recommendation to infringe any patents.