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What is extrusion? In the world of fencings and railings, the term “extrusion” refers to both a verb and a noun. The process of extrusion involves the shaping of a material (such as aluminum or vinyl) by forcing it through a die, i.e., a device used to cut or mold medal into a particular form. The object extrusion refers to a form or product produced through the extrusion process. For example, you might learn that the bottom rail of a vinyl fence contains aluminum extrusions for added support. To learn more about the extrusion process and the forms it can take, please scroll down.

What Is Extrusion?

We’ve already discussed a basic answer to the question, “What is extrusion?” However, it’s important to explore this process a little further, as there are two common methods employed in the manufacture of vinyl fencing: mono-extrusion and co-extrusion. Years ago, only a few manufacturers co-extruded vinyl fences. These days, just about all major manufacturers offer it as an option. In addition, all reputable companies back their products with protective lifetime warranties to give you peace of mind. To decide which method best suits your needs, you’ll need to understand the difference between the two.

Mono-Extrusion

Mono-extrusion produces a fence profile composed of a single layer. Since it only requires one extruder, the fixed-asset investment is far less per profile, and it requires less technical expertise to perform.

Ultraviolet inhibitors permeate mono-extruded products, inside and out. This is valuable on the outside of the product, of course, because it protects the vinyl material from sunlight. On the inside, however, ultraviolet inhibitors are unnecessary. You might shrug this off, but UV inhibitors are expensive – in fact, they’re typically the most expensive ingredient in the formula.

Co-Extrusion

Co-extrusion produces a fence profile made of two layers. As you might expect, it requires a larger investment by manufacturers: an investment in equipment, tools, training, and more. However, it does cost less than mono-extrusion when it comes to material prices. The two layers are chemically attached through great pressure and high temperatures, so that they forge a molecular bond and cannot be separated. Co-extrusion does not produce a laminate- or veneer-like product, as some opponents claim; the outer layer is quite thick, and two layers are very securely bonded together.

The outer layer (called the capstock) of co-extruded vinyl fencing contains a protective ultraviolet inhibitor; the inner layer (the substrate) offers reduced ultraviolet protection but may contain more impact modifiers for strength and flexibility. Thus, less of the pricey ingredient is wasted.

Finally, some manufacturers of mono-extruded fencing claim that because co-extrusion uses a different color of substrate material, if you scratch the fence, you will reveal the discolored substrate. Although this is true, if you purchase your fencing from a reputable, high-quality co-extruder, the exterior layer will be thick enough that a scratch won’t be able to penetrate it.

Comparing Your Options

As a consumer, should you purchase a mono-extruded or co-extruded fence? Luckily, the answer is quite simple. When it comes to quality, strength, UV performance, and available warranties, the two options are virtually the same. The primary difference resides in the cost: mono-extrusion costs more than co-extrusion. In addition, co-extrusion is a newer technology.

On the manufacturer’s end, you will find more differences between the two:

• Co-extrusions requires a higher investment for tooling and equipment.
• Mono-extrusion requires a higher material cost.
• Co-extrusion requires a higher level of expertise.

As a consumer, we encourage you to ask lots of questions of potential manufacturers about fences you are considering. Although the type of extrusion can affect the quality of the fence, remember that you can find excellent, high-quality fences that are both mono-extruded and co-extruded. Discuss the manufacturing process, fabrication techniques, extrusion technology, the ingredients involved, the design’s function, and (of course) the warranty to ensure you select the right fence for your needs.

For more help selecting an aluminum or vinyl fence, please check out these two previous blog posts: What to Look for in an Aluminum Fence and What to Look for in a Vinyl Fence.

Finally, if you’re interested in purchasing a new fence or railing, be sure to check out MMC Fencing & Railing. In our online store, you’ll find high-quality and virtually maintenance-free vinyl and aluminum fencing and railing systems. All of our products come with a protective warranty and are built to last a lifetime. To learn more about our fencing systems, please give us a call at 1-866-931-5002. We would be happy to help you select a fencing or railing system that fits your needs and to further explore the question, “What is extrusion?”