Plastic Shrinkage Rates for Molding Guide

Understanding Molding Shrinkage

Molding Shrinkage refers to the percentage reduction in the dimensions of a plastic part after it is removed from the mold and cooled to room temperature.

Because shrinkage is not only caused by the thermal expansion and contraction of the resin itself but is also related to various molding factors (such as pressure, temperature, and wall thickness), the shrinkage rate of a molded part is technically referred to as the Molding Shrinkage Rate.

> Note for Engineers: Accurate shrinkage data is critical for mold design to ensure the final part meets dimensional tolerances.

PA6 Series Shrinkage Rates (Nylon 6)

Polyamide 6 is known for its high mechanical strength and toughness. Below are the shrinkage rates for various modifications.

설명	Shrinkage Rate (%)	Grade Code
Glass Fiber Reinforced
15% Glass Fiber Reinforced PA6	0.5 - 0.8	PA6G15
20% Glass Fiber Reinforced PA6	0.4 - 0.6	PA6G20
30% Glass Fiber Reinforced PA6	0.3 - 0.5	PA6G30
40% Glass Fiber Reinforced PA6	0.1 - 0.3	PA6G40
50% Glass Fiber Reinforced PA6	0.1 - 0.3	PA6G50
Flame Retardant (FR)
25% GF Flame Retardant PA6	0.2 - 0.4	Z-PA6G25
30% GF Flame Retardant PA6	0.2 - 0.4	Z-PA6G30
30% GF Halogen-Free FR PA6	0.2 - 0.4	Z-PA6G30
Halogen-Free FR PA6	0.8 - 1.2	Z-PA6
Mineral & Filled
30% Mineral Filled Halogen-Free FR	0.5 - 0.8	Z-PA6M30
30% Glass Bead Filled PA6	0.8 - 1.2	PA6M30
30% GF + Mineral Composite	0.3 - 0.5	PA6M30
40% GF + Mineral Composite	0.2 - 0.5	PA6M40
30% Mineral Filled PA6	0.6 - 0.9	PA6M30
40% Mineral Filled PA6	0.4 - 0.7	PA6M40
General & Toughened
General Injection Grade PA6	1.4 - 1.8	PA6
Rapid Prototyping PA6	1.2 - 1.6	PA6
General Toughened PA6	1.0 - 1.5	PA6
Medium Toughened PA6	0.9 - 1.3	PA6
Super Toughened PA6	0.9 - 1.3	PA6
MoS2 Filled Wear-Resistant PA6	1.0 - 1.4	PA6

PA66 Series Shrinkage Rates (Nylon 66)

PA66 offers higher temperature resistance and stiffness compared to PA6.

설명	Shrinkage Rate (%)	Grade Code
Glass Fiber Reinforced
15% Glass Fiber Reinforced PA66	0.6 - 0.9	PA66G15
20% Glass Fiber Reinforced PA66	0.5 - 0.8	PA66G20
25% GF Heat/Oil Resistant PA66	0.4 - 0.7	PA66G25
30% Glass Fiber Reinforced PA66	0.4 - 0.7	PA66G30
30% GF Hydrolysis Resistant PA66	0.3 - 0.6	PA66G30
40% Glass Fiber Reinforced PA66	0.2 - 0.5	PA66G40
50% Glass Fiber Reinforced PA66	0.1 - 0.3	PA66G50
Flame Retardant & Filled
25% GF Flame Retardant PA66	0.2 - 0.4	Z-PA66G25
30% GF Flame Retardant PA66	0.2 - 0.4	Z-PA66G30
30% Mineral Filled Halogen-Free FR	0.2 - 0.4	PA66M30
Halogen-Free FR PA66	0.8 - 1.2	Z-PA66
30% Mineral Filled Halogen-Free FR	0.4 - 0.7	Z-PA66M30
30% Glass Bead Filled PA66	0.8 - 1.2	PA66M30
30% GF + Mineral Composite	0.2 - 0.5	PA66M30
30% Mineral Filled PA66	0.6 - 0.9	PA66M30
40% Mineral Filled PA66	0.4 - 0.7	PA66M40
General Grades
General Injection Grade PA66	1.5 - 1.8	PA66
Rapid Prototyping PA66	1.5 - 1.8	PA66
General Toughened PA66	1.2 - 1.7	PA66
Medium Toughened PA66	1.2 - 1.6	PA66
Super Toughened PA66	1.2 - 1.6	PA66
MoS2 Filled Wear-Resistant PA66	1.2 - 1.6	PA66

PP Series Shrinkage Rates (Polypropylene)

PP is a semi-crystalline material with relatively high shrinkage, which can be reduced with fillers like talc or glass fiber.

설명	Shrinkage Rate (%)	Grade Code
Talc Filled
20% Talc Filled PP	1.0 - 1.5	PPM20
30% Talc Filled PP	0.8 - 1.2	PPM30
40% Talc Filled PP	0.8 - 1.0	PPM40
20% Talc Filled Toughened PP	1.0 - 1.2	PPM20
Glass Fiber & Beads
10% Glass Fiber Reinforced PP	0.7 - 1.0	PPG10
20% Glass Fiber Reinforced PP	0.5 - 0.8	PPG20
30% Glass Fiber Reinforced PP	0.4 - 0.7	PPG30
20% Glass Bead Filled PP	1.2 - 1.6	PPM20
30% Glass Bead Filled PP	1.0 - 1.2	PPM20
General & Flame Retardant
Brominated Flame Retardant PP	1.5 - 1.8	PP
Halogen-Free Flame Retardant PP	1.3 - 1.6	PP
High Flow High Rigidity PP	1.5 - 2.0	PP
General Toughened PP	1.5 - 2.0	PP
Medium Toughened PP	1.4 - 1.9	PP
Super Toughened PP	1.3 - 1.8	PP
Weather Resistant
Heat Aging Resistant PP (1/2/3)	1.5 - 2.0	PP1/2/3
Impact Resistant Weatherable PP4	1.5 - 2.0	PP4
High Impact Weatherable PP5	1.5 - 1.8	PP5

PC Series Shrinkage Rates (Polycarbonate)

Polycarbonate has low shrinkage and high dimensional stability.

설명	Shrinkage Rate (%)	Grade Code
Glass Fiber Reinforced
10% Glass Fiber Reinforced PC	0.3 - 0.5	PCG10
20% Glass Fiber Reinforced PC	0.3 - 0.5	PCG20
25% Glass Fiber Reinforced PC	0.2 - 0.4	PCG25
30% Glass Fiber Reinforced PC	0.2 - 0.4	PCG30
Flame Retardant
20% GF Flame Retardant PC	0.2 - 0.4	Z-PCG20
25% GF Flame Retardant PC	0.2 - 0.4	Z-PCG25
30% GF Flame Retardant PC	0.2 - 0.4	Z-PCG30
20% GF Halogen-Free FR PC	0.2 - 0.4	Z-PCG20
30% GF Halogen-Free FR PC	0.1 - 0.3	Z-PCG30
Mineral Filled
20% Glass Bead Filled PC	0.3 - 0.6	PCM20

PC/ABS & PC/PBT Series Shrinkage Rates

These alloys combine the properties of Polycarbonate and ABS or PBT.

설명	Shrinkage Rate (%)	Grade Code
PC/ABS Alloys
20% Glass Fiber Reinforced PC/ABS	0.2 - 0.4	PC/ABSG20
Brominated Flame Retardant PC/ABS	0.3 - 0.6	Z-PC/ABS
Halogen-Free Flame Retardant PC/ABS	0.4 - 0.7	Z-PC/ABS
Weatherable PC/ABS	0.4 - 0.7	PC/ABS
PC/ABS (35% PC Content)	0.4 - 0.6	PC/ABS
PC/ABS (65% PC Content)	0.4 - 0.7	PC/ABS
PC/ABS (85% PC Content)	0.4 - 0.7	PC/ABS
PC/PBT Alloys
10% Glass Fiber Reinforced PC/PBT	0.5 - 0.8	PC/PBTG10
20% Glass Fiber Reinforced PC/PBT	0.4 - 0.6	PC/PBTG20
30% Glass Fiber Reinforced PC/PBT	0.3 - 0.5	PC/PBTG30
30% GF FR High Heat PC/PBT	0.3 - 0.5	Z-PC/PBTG30
High Impact High Heat PC/PBT	0.6 - 1.0	PC/PBT

ABS Series Shrinkage Rates

ABS is widely used for its impact resistance and surface finish.

설명	Shrinkage Rate (%)	Grade Code
Glass Fiber Reinforced
20% Glass Fiber Reinforced ABS	0.2 - 0.4	ABSG20
25% Glass Fiber Reinforced ABS	0.2 - 0.4	ABSG25
30% Glass Fiber Reinforced ABS	0.1 - 0.3	ABSG30
20% GF Flame Retardant ABS	0.1 - 0.3	Z-ABSG20
General Grades
General Flame Retardant ABS	0.4 - 0.7	Z-ABS
General Injection Grade ABS	0.4 - 0.7	ABS
Weatherable ABS	0.4 - 0.7	ABS

저자 소개

Alex Yu

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