What Is the Plastic Injection Molding Process?
The injection molding process refers to the process of making molten raw materials into a certain shape of semi-finished products through operations such as pressure, injection, cooling, and detachment.
Injection molding process
The injection molding process mainly includes 6 stages including mold closing --- filling-holding pressure-cooling-opening-molding. These 6 stages directly determine the molding quality of the product, and these 6 stages are a complete continuous process. This chapter focuses on the four stages of filling, holding pressure, cooling, and demolding.
Table 1 of injection molding process
Plastic name | LDPE | HDPE | Ethylene-propylene copolymer PP | PP | Glass fiber reinforced PP | PS | HIPS | ABS | High impact ABS | Heat-resistant ABS | Electroplated ABS | Flame retardant ABS | Transparent ABS | ACS | AS (SAN) | PMMA |
Injection process conditions |
| 1.Injection machine type | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line |
| 2.Screw form | 1 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 111 | 111 | 111 |
| Speed, r / min | 111 | 30-60 | 1 | 30-60 | 30-60 | 1 | 30-60 | 30-60 | 30-60 | 30-60 | 20-60 | 20-50 | 30-60 | 20-30 | 20-50 | 20-30 |
| 3.Nozzle form | 111 | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through |
| Temperature | 11 | 150-180 | 1 | 170-190 | 180-190 | 11 | 160-170 | 180-190 | 190-200 | 190-200 | 190-210 | 180-190 | 190-200 | 160-170 | 180-190 | 180-200 |
| 4. Before barrel temperature | 11 | 180-190 | 11 | 180-200 | 190-200 | 11 | 170-190 | 200-210 | 200-210 | 200-220 | 210-230 | 190-200 | 200-220 | 170-180 | 200-210 | 180-210 |
| Medium | 11 | 180-220 | 11 | 200-220 | 210-220 | 111 | 170-190 | 210-230 | 210-230 | 220-240 | 230-250 | 200-220 | 220-240 | 180-190 | 210-230 | 190-230 |
| After | 11 | 140-160 | 11 | 160-170 | 160-170 | 111 | 140-150 | 180-200 | 180-200 | 190-200 | 200-210 | 170-190 | 190-200 | 160-170 | 170-180 | 180-200 |
| 5. Mold temperature, | 30-45 | 30-60 | 50-70 | 40-80 | 70-90 | 11 | 20-50 | 50-70 | 50-80 | 60-85 | 40-80 | 50-70 | 50-70 | 50-60 | 50-70 | 40-80 |
| 6. Injection pressure, MPA | 11 | 70-100 | 11 | 70-120 | 90-130 | 11 | 60-100 | 70-90 | 70-120 | 85-120 | 70-120 | 50-100 | 70-100 | 80-120 | 80-120 | 90-120 |
| 7. Holding pressure, MPa | 1 | 40-50 | 1 | 50-60 | 40-50 | 1 | 30-40 | 50-70 | 50-70 | 50-80 | 50-70 | 30-60 | 50-60 | 40-50 | 40-50 | 40-60 |
| 8. Injection time, s | 1 | 2-5 | 1 | 2-5 | 2-5 | 1 | 1-3 | 3-5 | 3-5 | 3-5 | 2-4 | 3-5 | 2-4 | 2-5 | 2-5 | 2-5 |
| 9. Holding time, s | 1 | 15-60 | 1 | 20-60 | 15-40 | 1 | 15-40 | 15-30 | 15-30 | 15-30 | 20-50 | 15-30 | 15-40 | 15-30 | 15-30 | 20-40 |
| 10. Cooling time, s | 1 | 15-60 | 1 | 15-50 | 15-40 | 1 | 10-40 | 15-30 | 15-30 | 15-30 | 15-30 | 10-30 | 10-30 | 15-30 | 15-30 | 20-40 |
| 11, the total period, s | 1 | 40-140 | 1 | 40-120 | 40-100 | 1 | 40-90 | 40-70 | 40-70 | 40-70 | 40-90 | 30-70 | 30-80 | 40-70 | 40-70 | 50-90 |
| 12.Drying equipment | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling |
| Temperature | 90-100 | 90-100 | 100-120 | 100-120 | 100-120 | 90-100 | 90-110 | 100-110 | 100-110 | 100-110 | 100-110 | 100-110 | 100-110 | 1 | 1 | 100-120 |
| Time, h | <0.5 | <0.5 | <0.5 | <0.5 | <0.5 | <0.5 | 0.5-1.0 | 0.5-1.0 | 0.5-1.0 | 0.5-1.0 | 0.5-1.00 | 0.5-1.0 | 0.5-1.0 | 1 | 1 | 1.0 |
Injection molding process table two
Plastic name | PMMA / PC | Soft PVC | Rigid PVC | Chlorinated polyether | Homopolymer POM | Copolymer POM | PET | PBT | Glass fiber reinforced PBT | PA6 | Glass fiber reinforced PA6 | PA11 | Glass fiber reinforced PA11 | PA12 | PA66 | Glass fiber reinforced PA66 |
Injection process conditions |
1. Injection molding machine type | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line | Screw-line |
2.Screw form | 1 | 1 | 1 | 1 | 1 | 1 | mutation | mutation | mutation | mutation | mutation | mutation | mutation | mutation | mutation | mutation |
Speed r / min | 20-30 | 1 | 20-30 | 20-40 | 20-40 | 20-40 | 20-40 | 20-40 | 20-40 | 20-50 | 20-40 | 20-50 | 20-40 | 20-50 | 20-50 | 20-40 |
3.Nozzle form | Straight-through | 1 | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through | Straight-through |
Temperature, | 220-240 | 1 | 150-170 | 170-180 | 170-180 | 170-180 | 250-260 | 200-220 | 210-230 | 200-210 | 200-210 | 180-190 | 190-200 | 170-180 | 250-260 | 250-260 |
4.Before barrel temperature, | 230-250 | 1 | 170-190 | 180-200 | 170-190 | 170-190 | 260-270 | 230-240 | 230-240 | 220-230 | 220-240 | 185-200 | 200-220 | 255-265 | 260-270 | 1 |
Medium, | 240-250 | 1 | 165-180 | 180-200 | 170-190 | 180-200 | 260-280 | 230-250 | 240-360 | 230-240 | 230-250 | 190-220 | 220-250 | 190-240 | 260-280 | 260-890 |
After, | 210-230 | 1 | 150-170 | 180-190 | 170-180 | 170-190 | 240-260 | 200-220 | 210-220 | 200-210 | 200-210 | 170-180 | 180-190 | 160-170 | 240-250 | 250-260 |
5. Mold temperature | 60-80 | 1 | 30-60 | 80-110 | 90-120 | 90-100 | 85-120 | 65-80 | 70-110 | 60-100 | 80-120 | 60-90 | 60-90 | 70-110 | 70-120 | 100-120 |
6.Injection pressure, MPa | 80-130 | 1 | 80-130 | 80-110 | 80-130 | 80-120 | 80-120 | 60-90 | 80-100 | 80-110 | 90-130 | 90-120 | 90-130 | 90-130 | 80-130 | 80-130 |
7. Holding pressure, MPa | 40-60 | 11 | 40-60 | 30-40 | 30-50 | 30-50 | 30-50 | 30-40 | 40-50 | 30-50 | 30-50 | 30-50 | 40-50 | 50-60 | 40-50 | 40-50 |
8. Injection time, s | 2-5 | 1 | 2-5 | 2-5 | 2-5 | 2-5 | 2-5 | 1-3 | 2-5 | 2-4 | 2-5 | 2-4 | 2-5 | 2-5 | 2-5 | 2-5 |
9. Holding time, s | 20-40 | 1 | 15-40 | 15-50 | 20-80 | 20-90 | 20-50 | 10-30 | 10-20 | 15-50 | 15-40 | 15-50 | 15-40 | 20-60 | 20-50 | 20-50 |
10.Cooling time, s | 20-40 | 1 | 15-40 | 20-50 | 20-60 | 20-60 | 20-30 | 15-30 | 15-30 | 20-40 | 20-40 | 20-40 | 20-40 | 20-40 | 20-40 | 20-40 |
11.Total period, s | 50-90 | 1 | 40-90 | 40-110 | 50-150 | 50-160 | 50-90 | 30-70 | 30-60 | 40-100 | 40-100 | 40-100 | 40-90 | 50-110 | 50-100 | 50-100 |
12. Drying equipment | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling |
Temperature, | 100-120 | 60-70 | 70-80 | d1 | 110-120 | 110-120 | 150-170 | 120-135 | 120-135 | 120-130 | 120-130 | 100-120 | 100-120 | 100-120 | 120-130 | 120-130 |
Time, h | 1.0 | <0.5 | <0.5 | d1 | 0.5-1.0 | 0.5-1.0 | 2.0 | 2.0 | 2.0 | 0.5-1.0 | 0.5-1.0 | 0.5-1.0 | 0.5-1.0 | 0.5-1.0 | 0.5-1.0 | 0.5-1.0 |
Table 3 of injection molding process
Plastic name | PA610 | PA612 | PA1010 | Glass fiber reinforced PA1010 | Transparent nylon | Polycarbonate PC | PC / PE | Glass fiber reinforced PC | Polysulfone PSU | Modified PSU | Glass fiber reinforced PSU | Polyarylsulfone PAS | Polyethersulfone PES | Polyphenylene ether PPO | Modified PPO | Polyphenylene sulfide PPS |
Injection process conditions |
1. Injection molding machine type | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire | Screw-wire |
2.Screw form | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe | Catastrophe |
Speed r / min | 20-50 | 50-50 | 20-50 | 20-40 | 50-50 | 20-40 | 50-40 | 20-30 | 20-30 | 20-30 | 20-30 | 20-30 | 20-30 | 20-30 | 20-50 | 20-30 |
3.Nozzle form | Self-locking | Self-locking | Self-locking | Straight-through | Self-locking | Extended | Extended | Straight-through | Extended | Extended | Straight-through | Extended | Extended | Extended | Extended | Extended |
Temperature, | 200-210 | 200-210 | 190-200 | 190-210 | 220-240 | 230-250 | 220-230 | 240-260 | 280-290 | 250-260 | 280-300 | 380-410 | 240-270 | 250-280 | 220-240 | 280-300 |
4.Before barrel temperature, | 220-230 | 210-220 | 200-210 | 230-250 | 240-250 | 240-280 | 230-250 | 250-290 | 290-310 | 250-280 | 300-320 | 385-420 | 250-290 | 250-280 | 230-250 | 300-310 |
Medium, | 230-250 | 210-230 | 220-240 | 230-250 | 250-270 | 260-290 | 240-260 | 270-310 | 300-330 | 280-300 | 310-330 | 345-385 | 280-310 | 260-290 | 240-270 | 320-340 |
After, | 200-210 | 200-205 | 190-200 | 190-200 | 220-240 | 240-270 | 230-240 | 260-280 | 280-300 | 260-270 | 290-300 | 320-370 | 260-290 | 230-240 | 230-240 | 260-280 |
5. Mold temperature | 60-90 | 40-70 | 40-80 | 40-80 | 40-60 | 90-110 | 80-100 | 90-110 | 130-150
| 80-100 | 130-150 | 230-260 | 90-120 | 110-150 | 60-80 | 120-150 |
6.Injection pressure, MPa | 70-110 | 70-120 | 70-100 | 90-130 | 80-130 | 80-130 | 80-120 | 100-140 | 100-140 | 100-140 | 100-140 | 100-200 | 100-140 | 100-140 | 70-110 | 80-130 |
7. Holding pressure, MPa | 20-40 | 30-50 | 20-40 | 40-50 | 40-50 | 40-50 | 40-50 | 40-50 | 40-50 | 40-50 | 40-50 | 50-70 | 50-70 | 50-70 | 40-60 | 40-50 |
8. Injection time, s | 2-5 | 2-5 | 2-5 | 2-5 | 2-5 | 2-5 | 2-5 | 2-5 | 2-5 | 2-7 | 2-5 | 2-5 | 2-5 | 2-5 | 2-5 | 2-5 |
9. Holding time, s | 20-50 | 20-50 | 20-50 | 20-40 | 20-60 | 20-80 | 20-80 | 20-60 | 20-80 | 20-70 | 20-50 | 15-40 | 14-40 | 30-70 | 30-70 | 10-30 |
10.Cooling time, s | 20-40 | 20-50 | 20-40 | 20-40 | 20-40 | 20-50 | 20-50 | 20-50 | 20-50 | 20-60 | 20-50 | 15-20 | 15-30 | 20-60 | 20-50 | 20-50 |
11.Total period, s | 50-100 | 50-110 | 50-100 | 50-90 | 50-110 | 50-130 | 50-140 | 50-110 | 50-140 | 50-130 | 50-110 | 40-50 | 40-80 | 60-140 | 60-130 | 40-90 |
12. Drying equipment | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling |
Temperature, | 110-120 | 110-120 | 110-120 | 110-120 | 110-120 | 130-150 | 120-140 | 130-150 | 130-150 | 120-140 | 130-150 | 150-170 | 130-150 | 130-150 | 125-140 | 150-170 |
Time, h | 0.5-1.0 | 0.5-1.0 | 0.5-1.0 | 0.5-1.0 | 0.5-1.0 | 2.0 | 2.0 | 2.0 | 1.0-2.0 | 1.0-2.0 | 1.0-2.0 | 2.0 | 2.0 | 1.0-2.0 | 1.0-2.0 | 2.0 |
Table 4 of injection molding process
Plastic name | Polyimide PI | Polyarylate | Polyurethane | Tetrafluoroethylene-hexafluoropropylene copolymer FEP, F46 | Cellulose acetate CA | Cellulose acetate butyrate CAB | Cellulose acetate propionate CAF | Ethyl cellulose EC | Polypropylene thermoplastic elastomer PP / EPDM | Poly 4-methylpentene | PCTFE |
Injection process conditions |
1. Injection molding machine type | Screw-line | Screw-line | Screw-line | Screw-line | 1 | 1 | 1 | 1 | Screw-line | Screw-line | Screw-line |
2.Screw form | 1 | 1 | 1 | Catastrophe | 1 | 1 | 1 | 1 | Homogeneous gradient | Gradient | 1 |
Speed r / min | 20-30 | 20-50 | 20-70 | 20-30 | 1 | 1 | 1 | 1 | 25-50 | 20-30 | 20-30 |
3.Nozzle form | Extended | 1 | 1 | Extended | 1 | 1 | 1 | 1 | Straight-through | Straight-through | Extended |
Temperature, | 290-300 | 230-250 | 170-180 | 290-300 | 1 | 1 | 11 | 1 | 200-230 | 280-290 | 265-270 |
4.Before barrel temperature, | 290-310 | 240-260 | 175-185 | 300-330 | 11 | 1 | 1 | 11 | 200-230 | 290-310 | 275-280 |
Medium, | 300-330 | 250-280 | 180-200 | 270-290 | 11 | 11 | 1 | 11 | 200-230 | 250-270 | 280-290 |
After, | 280-300 | 230-240 | 150-170 | 170-200 | 11 | 11 | 11 | 11 | 190-220 | 230-250 | 200-210 |
5. Mold temperature | 120-150 | 100-130 | 20-40 | 110-130 | 1 | 11 | 1 | 1 | 38-66 | 80-130 | 80-130 |
6.Injection pressure, MPa | 100-150 | 100-130 | 80-100 | 80-130 | 1 | 1 | 1 | 1 | 35-138 | 80-130 | 80-130 |
7. Holding pressure, MPa | 40-50 | 50-60 | 30-40 | 50-60 | 1 | 1 | 1 | 1 | 28-110 | 30-50 | 20-60 |
8. Injection time, s | 2-5 | 2-8 | 2-6 | 1-3 | 1 | 1 | 1 | 1 | 3-5 | 2-5 | 1-3 |
9. Holding time, s | 20-60 | 15-40 | 30-40 | 20-60 | 1 | 1 | 1 | 1 | 15-45 | 20-60 | 20-60 |
10.Cooling time, s | 30-60 | 15-40 | 30-40 | 20-60 | 1 | 1 | 1 | 1 | 15-40 | 20-60 | 20-60 |
11.Total period, s | 60-130 | 40-90 | 70-110 | 50-130 | 1 | 1 | 1 | 1 | 30-100 | 50-130 | 50-130 |
12. Drying equipment | Horizontal boiling | Horizontal boiling | Horizontal boiling | Horizontal boiling | 1 | 1 | 1 | 1 | Horizontal boiling | Horizontal boiling | Horizontal boiling |
Temperature, | 150-170 | 1 | 1 | 1 | 80-90 | 80-90 | 80-90 | 80-90 | 100-110 | 120-150 | 1 |
Time, h | 2.0 | 1 | 1 | 1 | <0.5 | <0.5 | <0.5 | <0.5 | <0.5 | <0.5 | 1 [1] |
