US based Green Dot Bioplastics developed a wood-plastic composite for a client which it says is stronger, lasts longer and is easier to use than traditional posts
Kencove Farm Fence Supplies is a US wide manufacturer and distributor of electric fence supplies. Green Dot Bioplastics team has been collaborating with Kencove for years to develop consistently high quality and durable materials.
Traditional electric fence line posts require insulation for protection from the ground, PasturePro Posts are natural insulators, so there is no need to purchase insulators for the fence. The posts allow high-tensile wires to stretch and return to their initial tension after impact from wildlife or livestock.
This makes them suitable for cattle since they can handle significant animal pressure.
In developing the posts Green Dot had to balance the dielectric properties, tensile strength, memory capability, durability, flexibility, UV properties and recyclability.
Determining a formulation that met all these requirements as well as the cost target was challenging.
Green Forest Composites, the original manufacturer of PasturePro Posts, reached out to Green Dot Bioplastics who ran multiple trial productions with various combinations of polypropylene (PP) grades and wood, as well as various processing conditions.
A wood-plastic composite for heightened function
It was determined that high-grade PP was an optimal material due to its consistency, fatigue resistance, insulation properties and flexibility.
Wood fibre was used to add strength and lighten the weight of the posts. There were a wide range of wood species to pick from in the US, including oak, pine and maple that came in various particle sizes.
Choosing the correct one was critical since its properties would affect the manufacturing process.
There were several manufacturing challenges in the early 2000s. The orientation of wood-plastic composites was a newly patented process and everything from speed, length of the line, heating, cooling and die sizes were constantly being adjusted.
Green Dot Bioplastics was able to pinpoint a consistent wood pellet that could function within the formulation.
Green Forest Composites’ founder Steve Freeman recalls the hands on approach.
““I remember the service and attention Green Dots gave us. Eventually the company helped us develop a consistent wood pellet that worked.”
Traditional fiberglass posts have a tendency to splinter, especially as the
posts age or are flexed. They are also non-recyclable.
Both fiberglass posts and metal posts are liable to be displaced or pulled from the ground.
In addition, metal posts can pose an electrical ground hazard if the fence wire is knocked away from the insulator. They are also prone to rusting.
PasturePro Posts pose none of these threats. Recycling can be completed by grinding and adding them back in small amounts post production.
The wood-plastic composite also prevents the PasturePro Posts from splintering, rotting and rusting. The posts are also natural insulators so accidental grounding is not a concern.
The PasturePro Posts have received an organic certification from the Washington State Department of Agriculture, meaning that both Kencove’s manufacturing process and the wood-plastic composite developed with Green Dot Bioplastics have passed stringent regulations. The posts come with a 20-year warranty.
Learn more about designing and manufacturing with wood-plastic composites Download the Green Dot white paper, Working with wood-plastic composites