Plastic Material Shrinkage Guide

The chart below outlines typical mold shrink rates, as well as tonnage recommendations (per in²) and vent depth values (in),
for some commonly used injection molding materials.

Plastic material shrinks during the cooling phase of the injection molding cycle. Each resin shrinks differently depending on several factors which include: processing conditions, flow path, mold, part design, and material composition.

Use the chart to help you gather information about the typical shrinkage for a plastic resin.

Material Recommended Tonnage (per in²) Shrink Values Vent Depth (in.)
Acrylonitrile Butadiene Styrene (ABS) 2.5 – 3.5 .004 – .008 .0010 – .0020
ABS/Polycarbonate Blend (PC/ABS) 3.0 – 4.0 .004 – .007 .0015 – .0030
Acetal (POM) 3.0 – 4.0 .020 – .035 .0005 – .0015
Acrylic (PMMA) 3.0 – 4.0 .002 – .010 .0015 – .0020
Ethylene Vinyl Acetate (EVA) 2.0 – 3.0 .010 – .030 0005 – .0007
Ionomer 2.5 – 3.5 003 – .020 0005 – .0007
High-Density Polyethylene (HDPE) 2.5 – 3.5 .015 – .030 .0008 – .0010
Low-Density Polyethylene (LDPE) 2.0 – 3.0 .015 – .035 .0005 – .0007
Polyamide – Nylon (PA) Filled 4.0 – 5.0 .005 – .010 .0003 – .0010
Polyamide – Nylon (PA) Unfilled 3.0 – 4.0 .007 – .025 .0005 – .0020
Polybutylene Terephthalate (PBT) 3.0 – 4.0 .008 – .010 .0005 – .0015
Polycarbonate (PC) 4.0 – 5.0 .005 – .007 .0010 – .0030
Polyester 2.5 – 3.5 .006 – .022 .0005 – .0010
Polyetheretherketone (PEEK) 4.0 – 5.0 .010 – .020 0005 – .0007
Polyetherimide (PEI) 3.0 – 4.0 .005 – .007 .0010 – .0015
Polyethylene (PE) 2.5 – 3.5 .015 – .035 .0005 – .0020
Polyethersulfone (PES) 3.0 – 4.0 .002 – .007 0005 – .0007
Polyphenylene Oxide (PPO) 3.0 – 4.0 .005 – .007 .0010 – .0020
Polyphenylene Sulfide (PPS) 3.5 – 4.5 .002 – .005 .0005 – .0010
Polyphthalamide (PPA) 3.5 – 4.5 .005 – .007 .0005 – .0020
Polypropylene (PP) 2.5 – 3.5 .010 – .030 .0005 – .0020
Polystyrene (PS) 2.0 – 2.5 .002 – .008 .0015 – .0020
Polysulphone (PSU) 4.0 – 5.0 .006 – .008 .0010 – .0015
Polyurethane (PUR) 2.5 – 3.5 .010 – .020 .0004 – .0010
Polyvinyl Chloride (PVC) 2.5 – 3.5 .002 – .030 .0005 – .0020
Thermoplastic Elastomer (TPE) 2.5 – 3.5 005 – .020 .0008 – .0010

Disclaimer: All data and information presented are for information purposes only. Although this information is believed to be accurate to the best of our knowledge, they are provided without implied warranty of any kind. This data is intended for guidance and should not be considered as binding specifications. Before working with any material, users should contact material suppliers in order to receive specific, complete, and detailed information about the material they are considering. Plastics Plus and its partners do not claim responsibility for any decisions made as a result of this information.

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