A very complete list of common plastic injection molding technical parameters, please keep it!

Time:2022-06-08 09:09:21 / Popularity: / Source:

Before molding, plastic must be fully dried. After material containing moisture enters mold cavity, silver ribbon-like flaws will appear on the surface of workpiece, and even hydrolysis will occur at high temperatures, resulting in material deterioration. Therefore, material must be pretreated before molding process, so that material can maintain appropriate moisture.
plastic injection molding technical parameters 
For entry-level peers, this detailed list of injection molding parameters is a good memory method. For professionals, it is convenient to remember, simple and efficient.

1. Injection pressure

Injection pressure is provided by hydraulic system of injection molding machine. Pressure of hydraulic cylinder is transmitted to injection molding melt through screw of injection molding machine. Plastic melt is driven by pressure and enters main channel of mold from nozzle, is injected into mold cavity through winding mouth. Pressure is to allow melt to be injected into cavity according to process and to ensure complete filling.

2. Injection time

A reasonable injection time is helpful for filling of plastic melt, and injection time is generally about 1/10 of cooling time. It depends on different injection molding materials.

3. Injection temperature

Injection temperature is an important factor affecting injection pressure. Injection temperature must be controlled within a reasonable range. If temperature is too low, plasticization of raw materials will be poor; if temperature is too high, raw materials will be easily decomposed. Therefore, temperature control needs to be reasonably controlled by experienced masters.

4. Holding pressure and time

When injection molding is about to end, screw stops rotating, just pushes forward and enters pressure-holding stage. During pressure-holding process, nozzle constantly fills cavity with raw material melt to ensure integrity of product after molding. Holding pressure is generally about 80% of maximum filling pressure, which is determined according to requirements of actual raw materials and products.

5. Back pressure

Back pressure refers to pressure that screw needs to overcome when screw is reversed and withdrawn to store material. High back pressure facilitates dispersion of pigments and melting of plastics.
plastic injection molding technical parameters 

Injection molding parameters of common plastics

PP injection molding technical parameters

Drying temperature (℃) 65~75 Drying time about (hr) 0.5~1
Mold temperature (℃) 35~65 Residual material amount (mm) 3 to 10
Melting temperature (℃) 200~250 Back pressure (MPa) 9 to 17
Injection pressure (MPa) 80~130 Clamping force about (ton/in2) 2
Injection speed medium Return speed (rpm) 60~90
Screw category Standard screw (straight-through nozzle)
Downtime Just close gate and beer Recycled scraps (%) 15~30

Technical parameters of PE injection molding

Drying temperature (℃) 65~75 Drying time about (hr) 0.5 (do not need to dry)
Mold temperature (℃) 40~70 Residual material amount (mm) 3 to 10
Melting temperature (℃) 180~220 Back pressure (MPa) 7~18
Injection pressure (MPa) 80~130 Clamping force about (ton/in2) 2
Injection speed medium Return speed (rpm) 60~100
Screw category Standard screw (straight-through nozzle)
Downtime Just close gate and beer Recycled scraps (%) 20~40

Technical parameters of PVC injection molding

Drying temperature (℃) Do not need to dry, if it is wet, it needs to be dried below 70 ℃ for 1 hour.
Mold temperature (℃) 30~50 Residual material amount (mm) 2 to 6
Melting temperature (℃) 160~185 Back pressure (MPa) 4 to 8
Injection pressure (MPa) 70~110 Clamping force about (ton/in2) 2
Injection speed Slow or medium Return speed (rpm) 50~80
Screw category Standard screw (straight-through nozzle)
Downtime Cleaning with HDPE/PS Recycled scraps (%) 15~25

ABS injection molding technical parameters

Drying temperature (℃) 80 Drying time about (hr) 1.5
Mold temperature (℃) 45~80 Residual material amount (mm) 2 to 8
Melting temperature (℃) 190~235 Back pressure (MPa) 9 to 18
Injection pressure (MPa) 90~140 Clamping force about (ton/in2) 2~2.5
Injection speed medium Return speed (rpm) 70~100
Screw category Standard screw (straight-through nozzle)
downtime Just close gate and beer Recycled scraps (%) 20~30

PMMA injection molding technical parameters

Drying temperature (℃) 80 Drying time about (hr) 2 to 3
Mold temperature (℃) 40~70 Residual material amount (mm) 2 to 6
Melting temperature (℃) 215~240 Back pressure (MPa) 13 to 28 (higher)
Injection pressure (MPa) 100~170 Clamping force about (ton/in2) 4
Injection speed low speed Return speed (rpm) 60~80
Screw category Standard screw (if a larger injection pressure is required, a small screw can be used)
Downtime Need to use PP material to clean Recycled scraps (%) 0

PC injection molding technical parameters

Drying temperature (℃) 90~110 Drying time about (hr) more than 2 hours
Mold temperature (℃) 80~110 Residual material amount (mm) 2 to 8
Melting temperature (℃) 280~320 Back pressure (MPa) 6 to 15
Injection pressure (MPa) 130~180 Clamping force about (ton/in2) 4 to 6
Injection speed Medium or high speed Return speed (rpm) 60~80
Screw category Standard, thin (do not use dehumidifying screw and slingshot nozzle)
Downtime Clean with HDPE Recycled scraps (%) 10~25

PA66 injection molding technical parameters

Drying temperature (℃) 80 Drying time about (hr) 2 to 3
Mold temperature (℃) 50~90 Residual material amount (mm) 3 to 8
Melting temperature (℃) 260~290 Back pressure (MPa) 2 to 6
Injection pressure (MPa) 90~140 Clamping force about (ton/in2) 4 to 8
Injection speed High speed especially thin wall Return speed (rpm) 70~90
Screw category Standard screw (do not use dehumidifying screw), needle valve nozzle.
Downtime Just close gate and beer Recycled scraps (%) 5~15
Remarks: For nylon nozzle material decomposed due to high moisture content, its performance cannot be restored, and it is difficult to use again even if it is re-dried.

POM injection molding technical parameters

Drying temperature (℃) without drying If wet, dry below 100℃ for 2 hours
Mold temperature (℃) 40~90 Residual material amount (mm) 2 to 6
Melting temperature (℃) 190~215 Back pressure (MPa) 5 to 10
Injection pressure (MPa) 80~140 Clamping force about (ton/in2) 2 to 4
Injection speed medium speed Return speed (rpm) 50~70
Screw category Standard screw (straight-through nozzle)
Downtime Need to clean with PP/PE/PS material Recycled scraps (%) 30

PPS injection molding technical parameters

Drying temperature (℃) 120~130 Drying time about (hr) 2 to 3
Mold temperature (℃) 85~140 (plus heat insulation board) Residual material amount (mm) 3 to 10
Melting temperature (℃) 300~340 Back pressure (MPa) 5~12
Injection pressure (MPa) 100~150 Clamping force about (ton/in2) 4 to 5
Injection speed Medium to high speed Return speed (rpm) 60~80
Screw category Standard screw (straight-through nozzle)
Downtime Just close gate and beer Recycled scraps (%) 20~30

PC/ABS injection molding technical parameters

Drying temperature (℃) 80 Drying time about (hr) 2 to 3
Mold temperature (℃) 60~80 Residual material amount (mm) 3 to 6
Melting temperature (℃) 250~280 Back pressure (MPa) 5~12
Injection pressure (MPa) 80~140 Clamping force about (ton/in2) 3 to 4
Injection speed medium speed Return speed (rpm) 60~90
Screw category Standard screw diameter is 50mm, and it is better to use a screw with a low compression ratio for a large screw
Downtime Close gate to cool down injection Recycled scraps (%) 10~25

PBT injection molding technical parameters

Drying temperature (℃) 110~120 Drying time about (hr) 2 to 3
Mold temperature (℃) 50~75 Residual material amount (mm) 2 to 6
Melting temperature (℃) 250~270 Back pressure (MPa) 5 to 10
Injection pressure (MPa) 100~140 Clamping force about (ton/in2) 3 to 4
Injection speed high speed Return speed (rpm) 70~90
Screw category Standard screw (straight-through nozzle)
Downtime Just close gate and beer Recycled scraps (%) 15~25
Remarks: Fireproof PBT needs to use PE material to pass gun, and nozzle material should not be recycled.

PET injection molding technical parameters

Drying temperature (℃) 100~120 Drying time about (hr) 3 to 4
Mold temperature (℃) 120~140 Residual material amount (mm) 3 to 8
Melting temperature (℃) 260~295 Back pressure (MPa) 5 to 10
Injection pressure (MPa) 100~140 Clamping force about (ton/in2) 3 to 4
Injection speed high speed Return speed (rpm) 60~90
Screw category Standard screw (straight-through nozzle)
Downtime Need to use PE or PP material to clean barrel Recycled scraps (%) 10~20

PS injection molding technical parameters

Drying temperature (℃) 80 Drying time about (hr) 1 hour (usually without drying)
Mold temperature (℃) 40~60 Residual material amount (mm) 3 to 12
Melting temperature (℃) 180~220 Back pressure (MPa) 5 to 10
Injection pressure (MPa) 70~120 Clamping force about (ton/in2) 2
Injection speed fast Return speed (rpm) 60~100
Screw category Standard screw (straight-through nozzle)
Downtime Just close gate and beer Recycled scraps (%) 0

HIPS injection molding technical parameters

Drying temperature (℃) 80 Drying time about (hr) 1 hour (usually without drying)
Mold temperature (℃) 30~75 Residual material amount (mm) 4 to 10
Melting temperature (℃) 175~230 Back pressure (MPa) 5 to 10
Injection pressure (MPa) 60~110 Clamping force about (ton/in2) 2
Injection speed medium Return speed (rpm) 60~100
Screw category Standard screw (straight-through nozzle)
Downtime Just close gate and beer Recycled scraps (%) 15~30

K plastic injection molding technical parameters

Drying temperature (℃) Generally do not need to dry If wet, it needs to be dried at below 65℃ for about 1 hour.
Mold temperature (℃) 20~60 Residual material amount (mm) 3 to 8
Melting temperature (℃) 170~250 Back pressure (MPa) 3 to 10
Injection pressure (MPa) 60~100 Clamping force about (ton/in2) 2~2.5
Injection speed medium Return speed (rpm) 70~100
Screw category Ordinary standard type (when transparency requirement is high, choose a special screw)
Downtime Just close gate and beer Recycled scraps (%) 20~40

AS injection molding technical parameters

Drying temperature (℃) 80 Drying time about (hr) 1 to 2
Mold temperature (℃) 40~80 Residual material amount (mm) 3 to 10
Melting temperature (℃) 210~250 Back pressure (MPa) 5~15
Injection pressure (MPa) 100~140 Clamping force about (ton/in2) 2~2.5
Injection speed medium Return speed (rpm) 70~100
Screw category Standard screw (straight-through nozzle)
Downtime Just close gate and beer Recycled scraps (%) 0
 

Go To Top