Multi-Layer Co-Extrusion Blow Molding Equipment: How to Save Resin and Boost Quality

Introduction: What is Co-Extrusion?

Hello, friends! I am Slany Cheuang, the Technical Sales Manager here at LEKA Machine. If you have been in the packaging game for a while, you have definitely heard the buzz about “multi-layer” technology. But let’s skip the complicated jargon.

Think of multi-layer co-extrusion like making a sandwich. In a standard process, you bake a loaf of bread with just one ingredient. But with co-extrusion, you stack different ingredients to make something much better. While standard machines make a bottle from one single material, this technology allows you to use 2, 3, or even 6 layers at the same time.

This is becoming the new standard for factories that need to lower costs without making their bottles weak. In this post, we are focusing on Extrusion Soufflage (EBM) machines, specifically for HDPE and PP materials.

(New to EBM? Check out our full range of Machines d'extrusion-soufflage to see the basics.)

The Big “Why”: Saving Money with Recycled Materials

Let’s be honest: the main reason factory owners switch to this tech is simply to save money. We all want to cut down on raw material costs. This is where the “ABA” structure (3-layer) becomes a hero.

Imagine you use high-quality, brand-new “virgin” plastic for the outside and inside layers (the “A” layers). These are the parts the customer touches and sees. But the middle layer (the “B” layer)? That is where the magic happens.

You can fill this hidden middle layer with PCR (Post-Consumer Recycled) material or your own factory regrind. Since recycled material is much cheaper, your cost per bottle drops immediately. Plus, big brands love this because it helps them meet sustainability goals without making the bottle look ugly.

Optimizing the Production and Processing of Plastic Materials

When you move from single-layer to multi-layer, the production and processing of plastic materials changes slightly. It is no longer just about melting plastic beads; it is about flow management.

The machine uses multiple extruders—separate motors and screws—to melt different plastic types independently before they meet. At LEKA Machine, we design our screws to handle these materials gently. We don’t want to burn or “degrade” the plastic.

Why does this matter? Because efficient processing ensures the layers stick together perfectly. You never want delamination (where layers peel apart). Precision here means the production and processing of plastic materials results in a container that acts as one solid unit, even though it is made of three different parts.

For the Chemical Industry: The Magic of the View Stripe

If you make jerry cans for motor oil or chemicals, you know the “View Stripe” is a must-have. This is that thin, clear line running down the side of a colored bottle so users can see how much liquid is left.

It looks simple, but it requires a smart co-extrusion setup. We inject a strip of clear resin into the main plastic flow. It is a huge selling point for industrial packaging—turning a boring bottle into a useful tool for the user.

Keeping Products Safe: Barrier Layers

Sometimes, a plastic bottle needs to be a fortress. This is where “Barrier” technology (usually 4 to 6 layers) comes in.

Some products, like ketchup, dairy, or strong agrochemicals, are sensitive. Oxygen can spoil the food, or chemicals can slowly eat through standard plastic. To stop this, the machine sandwiches a shield layer—usually EVOH—deep inside the bottle walls.

This keeps oxygen out and chemicals in. It ensures your product stays fresh for a long time, which is critical if you are shipping goods internationally.

The Heart of the Machine: The Die Head

Let’s get a little technical, but keep it simple. The Die Head is the heart of the system. It is the funnel where all those different melted plastic streams meet.

A high-quality die head ensures the wall thickness is even all around. If the head is cheap or poorly made, you get thin spots (leaks) or thick spots (wasted money). At LEKA, our die heads are designed for stability and quick color changes, solving the painful “downtime” issue many factories face.