Polypropylene Injection Molding

Whether you need durable components or lightweight designs, our polypropylene injection molding services deliver precision, consistency, and quality to meet your production demands.

Home » Capabilities » Polypropylene Injection Molding

Erye Offer Polypropylene Injection Molding Service to Specific to Your Needs!

Polypropylene (PP) is widely used for its lightweight, durability, and chemical resistance, making it a top choice for various industries. We provide cost-effective and reliable PP injection molding solutions, ensuring your parts meet performance and quality standards.

Advanced Molding Capabilities: Precision molding for both simple and complex PP parts.
Custom Material Options: Includes reinforced and impact-modified PP grades.
In-House Tooling: Faster turnaround with optimized mold designs.
Secondary Services: Assembly, surface finishing, and package customization.

Injection Molded Polypropylene Design Guidelines

Polypropylene is relatively easy to mold. But still requires careful consideration of its high flexibility, low density and checmical resistance. Below are key design recommendations to optimize performance and manufacturability.

Item	Description
Wall Thickness	Maintain uniform wall thickness to prevent warping, sink marks, and differential shrinkage. Typical range: 0.5 mm to 5 mm, depending on part size and function.
Draft Angles	Include draft angles of 1-2 degrees on vertical surfaces to ensure easy part ejection from the mold.
Ribs and Bosses	Design ribs with a thickness of 50-60% of the nominal wall thickness to avoid sink marks; ensure bosses are properly supported (e.g., with ribs) to maintain structural integrity.
Radii and Fillets	Use radii and fillets with a minimum radius of 0.5 mm to reduce stress concentrations and improve mold flow during injection.
Shrinkage Considerations	PP has a shrinkage rate of 1.0–2.5%, so designs should accommodate dimensional stability.
Living Hinges	PP's flexibility allows for living hinges, but the hinge thickness should be 0.25–0.5 mm for durability.
Stiffening Features	For large or flat parts, add ribs or other stiffening elements to prevent warping, especially given PP’s higher shrinkage tendencies.

Key Properies of PP Molding Material

Polypropylene (PP) properties can vary significantly depending on the specific grade (homopolymer, copolymer, etc.) and any additives used. Here's a general overview of key properties with typical data.

Property	Value/Range	Description
Density	0.898 - 0.908g/cm³	Varies slightly between homopolymer and copolymer.
Melting Point	Homopolymer: 160 - 165°C; Copolymer: 135 - 159°C	Copolymer has a lower melting point.
Tensile Strength (Yield)	20 - 40 MPa	Range reflects variations in PP types.
Elongation at Break	15 - 700%	Wide range due to different PP formulations.
Flexural Modulus	1.1 - 1.6 GPa	Reflects stiffness; higher for homopolymer.
Water Absorption (24 hrs)	<0.01%	PP is highly hydrophobic.
Heat Deflection Temperature (HDT)	50-60°C	HDT A (1.8 MPa)

Key Considerations:

Homopolymer vs. Copolymer:
- Homopolymer PP is generally stiffer and stronger.
- Copolymer PP offers better impact resistance, especially at low temperatures.
Additives: Fillers like glass fibers or talc can significantly enhance PP’s mechanical properties.
Temperature: PP’s properties can change with temperature, and it’s not well-suited for high-temperature applications

Start PP Molding Project

Get high-quality PP injection molded parts! Contact with Erye to request a quote!

Advantages of PP Injection Molding

Cost and Efficiency

PP is relatively inexpensive compared to other materials, making it an economical option for mass production. Its favorable processing window leads to efficient production, reducing cycle times and overall costs

Low Density & Lightweight

PP's low density translates to lighter parts, reducing material costs and weight in applications like packaging and automotive.

Food Contact Safe

Many PP grades are approved for food contact, making them suitable for packaging and food storage applications.

High Flexural Fatigue Resistance

PP can withstand repeated bending, flexing, and impacts, making it suitable for snap fits, hinges, and living hinges.

PP Injection Molding Applications

Packaging

Food containers
Bottle caps and closures
Medicine bottles
Storage boxes and bins
Cosmetic packaging (lids, jars)

Automotive

Battery cases
Interior trim parts (door panels, dashboards)
Fluid reservoirs (washer fluid, coolant)
Air ducts and housings

Medical

Syringe barrels
Specimen containers
Medical device housings
Pipette tips
Diagnostic test cassettes

Industrial

Chemical storage tanks
Battery cases
Industrial containers
Pipe fittings
Material handling trays

Additonal Options for Polypropylene Parts