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Production

composite decking production

Click on any of the questions below to find out more about the production process of plastic wood composite decking

Not all composite decking is alike – so what’s in this stuff?

Composite products have shown phenomenal growth internationally and, in the USA alone, represents more than a billion dollar industry.  No other building product has grown this quickly and there is an impressive mix of product performance achievements coupled with some dumb manufacturing errors that has left the industry with a mixed bag of products and professional opinions.  Most homeowners, professional contractors and architects will be able to determine the qualities and performance characteristics of most timber species as well as which wood will suit which climate in Africa from Balau decking in Cape Town to Teak decking in Gauteng. But then try ask the same customer base to explain what makes one brand of composite decking different from another and a lot of the same individuals are stumped. The composite industry is fast paced and changing rapidly, and it is therefore imperative for any homeowner, professional or architect to understand what a composite product is in the first place and why it is different from plastic decking and the things to look out for when purchasing a particular brand of composite decking.

How to make plastic wood? It’s as much art as it is science

Creating a composite product is much like industrial baking except you are working with inconsistent raw materials to produce a consistent product.  Composite decking or wood plastic composite decking (WPC decking) is made from reclaimed wood, mixed with a sophisticated blend of recycled plastic products.  Typically the blend of a composite material is 50/50 recycled wood fibres and plastics. Typically 95% of the product is made from recycled material and the balance with additives for enhanced performance and aesthetics. There are some good composite materials and some not-so-good composite materials. The quality and performance of a composite material depends on the type and characteristics of the raw materials used in the manufacturing process and the patented production processes used to manufacture the material.

Creating a consistent quality finished product is a technologically daunting task, so how is this stuff made and what are the things to look out for?
1. Source & clean raw material
Producing a composite material is very much like industrial baking. You need plastic (virgin or recycled), wood flour and additives. You can relate to the competitiveness of the industry like a good old South African braai. Like each braai master, every supplier keeps their recipe of core ingredients, spices and production techniques a secret but most suppliers share the same basic principles which are described below.
2. Prepare and mix ingredients
The wood flour or chips used in wood plastic composite decking has to be free of moisture and, before going through the extruder, it gets heated up and dried to remove all moisture content. At the same time, the plastic, which is in flake size, is heated up into a liquid state. The combination of wood and plastic is heated up together whilst additives are added to the mixture. The end process is a hot, doughy type mixture on an industrial scale.
3. Extrude the mixture
The hot mixture is fed into the extruder and pushed through a mould or die, into the required profile or shape. It is at this stage that the manufacturing process differs between manufacturers as some suppliers do not immediately cool the product, whilst some immediately place the product in cool water for quick handling. This process is a highly guarded secret and directly affects product performance.
4. Cool what’s produced
The extruded product now has the right shape and can be cut to the required length but is still so hot that it is as flexible as over cooked spaghetti. Stiffness comes as the product cools, which is a time-consuming process. Most suppliers place the extruded product into cooled water or spray water on the product but this has its own set of problems. A misdirected spray can cause the product to bulge in certain places and can cause product defects if cooled too quickly – so the method of cooling is critical to product performance. At this stage, a manufacturer can quality test and see if the product has been produced according to specifications or if the product has to be heated up again and re-extruded.
5. Cut, emboss, wrap
By now the product has cooled to the point where its surface can be sanded down or can receive an imprint with a wood finish. Typically an imprint is achieved with a big wheel that contains a random pattern and some manufacturers add extra additives for enhanced performance or aesthetics at this stage. If the profile is wrapped and shipped to site before it has completely cooled, this can cause a variety of problems.

So what makes Envirodeck different to other composites?

It has everything to do with its production. Saying that all composite products are alike is the same as saying that all vehicles are the same. This is not true and the same can be said for the production of composite products.

Envirodeck products undergo a patented encapsulation process during production wherein the recycled wood fibres are aligned and encapsulated in recycled plastic which gives them outstanding, value-added properties when compared to other composite decking materials that simply mix the wood fibre and plastic together.  Wrapping plastic around a wood fibre prior to extrusion is key to protecting the wood inside and essentially differentiates AERT® Inc. from any other manufacturer and is what sets it apart from the competition.

Besides the above process, below is a short description of what makes AERT® Inc. production different to other composite decking products:
Raw Materials
Envirodeck products do not contain wood flour, only wood pulp of larger sizes, making it easier to encapsulate with plastic (smaller wood fibres allows a higher degree of water absorption and staining).
Red oak fibre is used instead of bamboo or saw dust found in other composites, which is free of tannins (this provides a moisture-free and stable wood fibre).
The wood fibres are encapsulated with recycled HDPE, LLDPE & LDPE plastic blend components which is unique compared with some manufacturers who use virgin plastic.
Products are extruded with metallic oxide pigments for desired colour which creates neutral tones and natural weathering. Other composite products require dense colouring or finishing which does not look natural or is not aesthetically pleasing.
Recycled Material
AERT® controls the entire value chain, from the reclamation process and filtering the raw material right through to the delivery of the end product to achieve stable, consistent finished products. This is because AERT is a recycling company with a track history.
Recycled material saves energy, reduces greenhouse gasses, creates jobs and lowers costs throughout the lifecycle of the product rather than using virgin material.
Encapsulation Process
Prior to encapsulation, the wood is heated to just below flash point to remove any existing moisture.
This process gasses the tannins and lignin – eliminating oils in the wood and allowing a better bond with the plastics in the encapsulation process. This process prevents rotting, decay, warping and splintering.
Extrusion Process
AERT does not water cool the boards in the manufacturing process but instead allows the board to cool very slowly through a drying process and this gives the board stability and superior strength. This process allows the plastic to cool down naturally which minimises thermal expansion which is an issue with other composite products. This process provides a recycled product that in essence, behaves in the same predictable manner as timber decking.
Testing
Envirodeck products undergo multiple testing methods to ensure compliance with international specifications:
ICC Compliance Testing
Static Bend Testing
Thermal Movement Testing
Moisture Testing
Colour Consistency Checks
Weatherometer Testing
The Result
Envirodeck composite decking products have the advantage over other composite materials:
Greater resistance to moisture, mold, mildew and staining
Uniformity with vibrant lasting colours
Longer product lifespan
Boards that are more durable and stable
Does not splinter, warp or decay with time

So how do you know the variations between composite product and how do you tell which product is a peach and which one is a lemon?

Ask the below questions and check the following prior to making any purchasing decision:
Why does a product cost more or vary in warranty? Knowing what’s in the product and what is extra can help you decide if the product is worth purchasing at a certain price. Compare apples with apples.
Ask your supplier about product recalls and lawsuits? The volume of claims versus percentage of sales is a sure indicator of product performance – check testimonials with other customers prior to purchasing. Ask for a reference list from the supplier.
How long has the company been in business and the product been tested in the market? The only sure way to tell of the products quality is to check if a lot of it has been installed in a variety of places and installations. What is the track history of these various installations?
Ask if the product expands and contracts and if the products colours can affect the product’s performance? The darker colours make expansion and contraction an even greater problem.
Do sufficient research on pricing versus performance. Not all products are what they are marketed to be.

In essence, composite decking is a fast paced, evolving industry and understanding how it’s made, where it’s made and its track history is your first step in reducing your risks as a customer.  Do not accept what suppliers say at face value and check how closely a supplier backs up their word. A little research ahead of time can save a great deal of hassle and money for replacement products further down the line.