Does the Foam Injection Molding Machine Production Line need to be cleaned?

1. Why is it necessary to clean a foam injection molding machine production line?

To ensure product quality (the most direct reason):
Prevent impurity contamination: Residual plastic, masterbatch, foaming agent, or other impurities from previous production runs can mix into new products, causing black spots, streaks, surface defects, or substandard performance.

Prevent material degradation: Foaming materials (such as EPP, EPO, and EPE) can carbonize and degrade when exposed to heat in the barrel for extended periods. These carbonized materials can contaminate subsequent products, especially when changing colors or materials.

Ensure foaming uniformity: Residues can interfere with uniform mixing and decomposition of the foaming agent, resulting in uneven product density and poor cell structure.

Maintain normal equipment operation:
Prevent clogging: Foaming material can easily accumulate and carbonize in dead corners such as nozzles, check rings, and hot runners, causing blockages and impacting injection and holding pressure.
Protect the screw and barrel: Carbonized, hard residues can increase wear on the screw and barrel.

Ensure sensor accuracy: If the material level sensor, pressure sensor, etc. are contaminated, they will transmit erroneous signals, causing the production parameters to be out of control.
Ensure production safety: Some chemical foaming agents or their decomposition products may be corrosive or toxic and need to be thoroughly cleaned.
The cleaning process itself is also a good opportunity to check whether the equipment has safety hazards such as leakage and damage.

2. Which parts should be cleaned? How to clean?

The cleaning of the foam injection molding machine production line needs to be carried out systematically, mainly targeting all the paths through which the material passes.

(1). Cleaning before stopping (transition cleaning)

This is the most commonly used and most economical method. At the end of production, switch to pure PP or PE cleaning materials to completely discharge the remaining foaming material in the barrel until the ejected material strips no longer have foaming and the color is pure.

(2). Deep cleaning of the screw and barrel

Special cleaning materials: Use polymer grinding cleaning materials or chemical cleaning agents designed for foamed plastics. It can effectively decompose and remove carbonized deposits on the screw and barrel wall.
Manual disassembly cleaning (most thorough):
After the equipment is completely cooled, professional maintenance personnel will pull the screw out of the barrel.
Use non-destructive tools such as copper brushes and brass scrapers with solvents to manually remove all residues.
Key: The screw head, check ring (glue head) and other parts that are most prone to material accumulation and carbonization must be carefully cleaned.
After cleaning, reassemble and apply an appropriate amount of high-temperature grease.

(3). Cleaning and maintenance of the mold

Vent grooves/holes: The vent grooves of the foaming mold are easily clogged by residues and must be thoroughly cleared with a special ejector or tool, otherwise it will cause insufficient filling or burning.
Mold cavity surface: Use mold cleaning agents, alcohol, etc. to clean the mold cavity to ensure a smooth surface, facilitate demolding and ensure the appearance of the product.
Hot runner system: If the mold has a hot runner, it is necessary to use cleaning materials or disassemble it for special cleaning to prevent degradation of the material in the runner.

(4). Cleaning of auxiliary systems

Mold cooling water channel: Clean it regularly with a descaling agent to prevent scale from affecting the cooling efficiency, thereby causing uneven shrinkage or deformation of the foamed product.
Feeding system: Clean the dryer and hopper to prevent moisture absorption and the introduction of impurities.

3. Cleaning frequency recommendations

Every time you change materials/colors: a thorough transition cleaning (using cleaning materials) must be performed. During regular maintenance: Depending on production volume and material properties, the screw should be pulled out for inspection and deep manual cleaning after every period of operation (e.g., several months or after reaching a certain output).

Before long-term downtime: The barrel must be emptied with cleaning material or a stable pure resin (such as PP) to prevent internal carbonization of the material.