Nanjing Kelongwell Twin-Screw Extruder: A Highly Efficient And Professional Emergency Screw Cleaning Method After Trial Use

During the testing or formulation changeover of twin-screw extruders, emergency screw cleaning is a highly technical operation-not only must residual material be removed in the shortest possible time, but operational safety must also be considered to avoid damage to screw components and cylinder walls. Based on years of field service experience, Nanjing Kelongwell has summarized a set of efficient, safe, and professional emergency cleaning solutions to help numerous customers quickly resume production in emergency situations.

When cleaning the screw of a twin-screw extruder, the first step is to select a suitable cleaning method based on the characteristics of the residue. For thermoplastic general-purpose plastics (such as PP) and PE, the "displacement cleaning method" can be used-maintaining the cylinder temperature at the upper limit of the current material processing temperature, adding a high-flowability cleaning material (such as PP or PE powder mixed with a small amount of stearic acid) for continuous extrusion, and gradually displacing the residual melt using the high flowability of the cleaning material. The core of this method is "no shutdown, no cooling," achieving a gentle switchover through the mutual dissolution principle between polymer melts. For heat-sensitive or easily cross-linked materials (such as PVC, TPU, and cross-linked polyethylene), a "segmented cooling disassembly method" is required. The specific steps are: first, lower the cylinder temperature below the material's softening point to make the residue brittle, then disassemble the screw components for mechanical cleaning. During this process, do not forcibly rotate the screw to avoid damaging the bond between the brittle material and the metal surface, causing scratches on the screw components.

For emergency situations, Nanjing Kelonwell recommends the "concentration gradient replacement method." Fifteen minutes before shutdown, mix the cleaning material with the base resin in different ratios: pure resin, resin:cleaning material = 3:1, 1:1, 1:3, and then pure cleaning material. Feed these continuously, using a concentration gradient to gradually dissolve and peel away the residue from the cylinder wall and screw surface. The scientific basis for this method is that cleaning materials with different concentration gradients can effectively break the interfacial bond between the residue and the metal surface, increasing cleaning efficiency by 30%-40% compared to adding a large amount of pure cleaning material at once. Nanjing Kelonwell also recommends adding an appropriate amount of fluorescent whitening agent or lubricant to the cleaning material to determine when cleaning is complete-the process is considered complete when the extruder shows no obvious fluorescent residue under UV light or its surface gloss returns to normal.

Regarding operational safety, emergency cleaning of twin-screw extruders must adhere to the principle of "power off and material off." Before cleaning, turn off the main feed, wait 10-15 seconds, and disconnect the main power supply to prevent sudden impact on the screw load during cleaning. When disassembling screws, use a dedicated puller tool instead of a hammer to avoid deformation of the screw shaft or damage to the splines. After cleaning, the screw components should be immediately rust-proofed and coated with a dedicated lubricant for future use. This efficient and safe cleaning process significantly reduces downtime and lowers the risk of equipment damage during operation. Nanjing Kelonwell consistently provides professional support services to its customers.