extruded polyethylene foam
Polyethylene (PE) and polypropylene (PP) foams are incredibly versatile materials that are used in different capacities throughout various industries. In construction the foams can be used for soundproofing, thermal insulation, and reflective thermal insulation. In the automotive industry they can be used to soundproof a vehicle's interior. In the food industry they are used in single use tableware. And one of the more widely popular applications for PE and PP foam is packaging. But no matter the application, foam manufacturers must always strive for quality, efficiency, and transparency, especially when supplying all-important foam products in regulated industries. ​
With this in mind, it's no wonder foam manufacturers consistently look to incorporate sophisticated foam extrusion technology into their manufacturing process. Employing the right equipment and machinery goes a long way in boosting productivity and efficiency and with a bit of creativity and customization a competitive advantage can be feasibly achieved.  
​​

FAP Foam Extrusion Technology

Among foam extrusion equipment manufacturers, our partner FAP Italy separates itself from the competition by offering foam extrusion lines that are industry proven. FAP’s foam machines are robust, reliable, and sustainable. Their foam extrusion machines boast a twin-screw counter-rotating design that offers several improved features unique to FAP foam extrusion machines. These unique features include superior mixing and melting of process additives, improved dispersion of gas in the melt, microcell technology, excellent energy efficiency, fully automated systems, and various controls and advantages for quick technological and manufacturing adjustments. ​
 Enhanced Mixing of Process Additives  
Twin screw extrusion is by far the most optimal process for foam production. The mechanical sheer and mixing capabilities of a twin-screw extruder far surpass those of a single screw extruder. FAP twin-screw counter-rotating extrusion machines achieve superior uniformity and consistency of the melt by grinding the material at the screw contact point, thereby avoiding melt backpressure as is common with single-screw extruders. These advantages have various positive effects throughout the mixing/melting process including: 
  • Reduced friction during the melting stage, which leads to decreased surface tension of the melt. All of which has an enhanced effect on the characteristics of the foam material including optimal cell wall thickness and density, reduced % residual deformation in compression, and increased dynamic modulus of the elasticity of the polyethylene and polypropylene foams when under load. 
  • Significant improvements in the mixing of additives and other agents in the melt; anything from dye concentrates, nucleators, and sliding agents to flame retardants and others. Optimal mixing of these various additives and agents leads to reduced time spent in adjusting the recipe during foam production and decreases in technological waste. 
  • Improved cooling and stability of the foamed polymer’s behavior during degassing. This is achieved thanks to FAP’s counter-rotating technology, which ensures that the melt is kept in constant rotation in the barrel. These factors help avoid negative effects such as localized points of overheated polymer and the overexpansion or collapse of the finished foam material. ​
Improved Dispersion of Gas in the Melt  
The mixing of the melt with gas is a key process in the manufacturing of non-crossed linked physically foamed polyethylene and polypropylene. The use of Inadequate extrusion machinery can lead to significant limitations in the production process and limitations in the thickness of the foam that can be produced. These issues primarily stem from inadequate pressure in the gas injection zone, which leads to back pressure in the extruder barrel and filter screen and results in the mentioned limitations. 

FAP foam extrusion lines employ a twin-screw design with counter rotating action that allow for various advantages in gas dispersion. Such advantages include: 
  • Sufficient pressure to the gas inlet zone of the extruder, all while maintaining adequately low pressure at the die outlet of the extrusion head. 
  • Additionally, the unique design of the screws at the inlet zone create a stronger mixing effect and allow for changes in the flow direction of the melt, all of which enables the gas to be dispersed with greater uniformity, resulting in a more homogeneous fine cellular structure (Microcell Technology). 
  • All of these factors allow for the production of foamed polyethylene (PE) and polypropylene (PP) at critically high and sufficiently low pressures, with greater range of product thickness from 0.5mm to 25mm, and with a smooth low density foamed polyethylene and polypropylene without waves on the same extrusion line. ​
​
Picture
Enhanced mixing of Process Additives With FAP Twin Screw Extruder
Picture
FAP Extrusion Technology
Picture
Photo 1. Production of 5 mm thick physically foamed polyethylene with high and frequent waves Photo 2. Production of physically foamed polyethylene with thickness of 20 mm with flat smooth surface
Picture
Production of 5 mm thickness low density polypropylene foam with flat smooth surface on extrusion line FAP.

Advantages of FAP Twin Screw Counter-Rotating Foam Extruder

Picture
Advantages of FAP Twin Screw Counter-Rotating Foam Extruder

Cost Savings with FAP Extrusion Technology

FAP extrusion machines offer several technological advantages that can help manufacturers obtain significant cost savings. Important factors that contribute to costs savings include enhanced cooling of the melt, ease of adjustment to target the intended foam product, and improved mixing of additives and co-agents. These factors enable a stable and efficient production process with controlled quality indicators, which minimizes hidden defects, shrinkage of the foam during degassing, and cell structure integrity issues. FAP foam extrusion machines can produce high quality foam products with a low margin of defects and other issues, saving time and minimizing wasted material and effort. Additionally, FAP machines can start up and finish production of foam products much faster when compared to a single screw extruder. In fact, the time from start up to finished product is about 15-20 minutes faster on a FAP extruder. This not only saves time but also reduces energy consumption. As mentioned, consumption of raw materials is also greatly reduced, which directly contributes to the reduction of the minimum economically efficient production batch by 10-14%. Additionally, these factors also significantly reduce warehousing and storage costs.  ​