Types of Foam Densifying Machines
Cold Compression Type
Cold compression foam densifiers compact EPS foam without any heating. The material is fed and compressed directly by a screw system. At the 2010 K Show in Germany, a compact screw-type densifier demonstrated a processing capacity of approximately 13.6–18.4 kg/h. The final foam density can be increased by up to 40 times, with compaction densities reaching as high as 320.5 kg/m³.
Hot Compression Type
Hot compression densifiers are mainly designed for PU foam recycling. Compared with cold compression models, these machines are equipped with a heating section in the compression chamber. The material passes through the heated zone and is discharged in a semi-molten state. Heger showcased this type of machine at the 2007 K Show in Germany. This design offers higher compaction density and can achieve production capacities exceeding 500 kg/m³.
Hot Melting Type
Hot melting foam densifiers operate in a manner similar to plastic extrusion pelletizing machines. The foam is completely melted and then extruded through the discharge outlet. Like hot compression models, this design requires one or more heating modules, resulting in higher energy consumption and equipment complexity.
Hydraulic Compression Type
Hydraulic foam densifiers utilize a screw-free design. Instead of mechanical extrusion, hydraulic force is applied to compress the material within a confined chamber, significantly increasing its density. Although more complex than other types, hydraulic densifiers offer the highest compaction efficiency and can achieve densities exceeding 700 kg/m³.
Structure and Working Principle
Screw Compression System
The core operating principle of a foam densifier (cold press type) is based on the pressure generated by a rotating screw. During operation, waste foam is fed through the hopper and first shredded into smaller pieces by the crushing unit. The material is then transported into the screw compression chamber, where it is compacted into dense blocks. This process greatly reduces storage volume and improves transportation and recycling efficiency.
Hydraulic Compression System
Another common design uses hydraulic compression technology. A hydraulic ram continuously applies force within a compression chamber, forming high-density foam blocks without generating harmful gases during operation.
Main Components
A typical foam densifying machine generally consists of the following parts:
Feeding hopper
Shredding and crushing unit
Screw compression system (for screw-type models)
Hydraulic compression system (for hydraulic models)
Machine frame
Compression chamber
Hydraulic ram
Compression drive unit
Block-forming chamber
Block discharge mechanism
For example, a patented waste foam densifier design includes a frame, machine housing, compression ram, hydraulic drive system, block-forming chamber, and discharge unit. The machine housing is equipped with a feeding inlet, compression port, and finished block outlet to ensure continuous and efficient operation.
