PE-LD (Low-Density Polyethylene): Applications, Advantages & Injection Molding Guide

PE-LD (Low-Density Polyethylene): Applications, Advantages & Injection Molding Guide

PE-LD, or Low-Density Polyethylene, is a flexible and lightweight thermoplastic known for its toughness, chemical resistance, and ease of processing. It is widely used in packaging, consumer goods, medical products, and electrical insulation.

What Is PE-LD?
PE-LD is created through the high-pressure polymerization of ethylene, resulting in a polymer with substantial branching. This gives it lower density, softer texture, and greater flexibility compared to PE-HD. Its low crystallinity and low melting point (about 110 °C) make it ideal for molding and extrusion processes.

Key Applications of PE-LD

Packaging
– Plastic bags and shrink wraps
– Food containers and bottle caps
– Squeeze bottles and liners

Medical & Healthcare
– Tubing and disposable covers
– Sterile packaging
– Laboratory pouches and trays

Consumer Goods
– Flexible lids and containers
– Toys and soft household items
– Kitchenware and garden hoses

Electrical & Cable
– Wire and cable insulation
– Flexible conduit jackets
– Protective sleeves

Industrial
– Liners and film coatings
– Chemical storage bin liners
– Protective layers in construction

Advantages of PE-LD
– Excellent flexibility and toughness
– High impact resistance even at low temperatures
– Superior chemical and moisture resistance
– Easy to mold and weld
– Good electrical insulation properties
– Low cost and widely recyclable

Injection Molding Guidelines for PE-LD

1. Drying Requirements
PE-LD is not hygroscopic and typically does not need drying.
– Drying: Generally not required unless exposed to moisture
– Optional drying: 60–70 °C for 1–2 hours if needed

2. Melt and Mold Temperatures
– Melt temperature: 180–280 °C
– Mold temperature: 20–40 °C
– Use adequate cooling channels to ensure uniform shrinkage and stability

3. Injection Pressure & Speed
– Pressure: Up to 1500 bar
– Holding pressure: Up to 750 bar
– Speed: High-speed injection recommended for better fill and surface finish

4. Runner and Gate Design
– Compatible with all standard gates: submarine, fan, edge
– Gate length: ≤0.75 mm to minimize shear stress
– Hot runner systems are well-suited to PE-LD if properly balanced

Common Molding Issues
– Warpage: Use uniform wall thickness and mold temperature
– Stringing: Control melt temp and improve mold cooling
– Flashing: Adjust clamping force and gate design
– Environmental stress cracking: Choose appropriate grades and processing conditions

Final Thoughts
PE-LD is a go-to material for flexible, durable, and low-cost molded products. It excels in high-volume production of consumer packaging, medical disposables, and cable insulation. With easy processability and good mechanical balance, PE-LD is a reliable material across many industries.
Need guidance on PE-LD blends or FDA-compliant grades? Our specialists are ready to support your product development and molding optimization.