Influence of thermo-mechanical operating stresses on the tendency of coated steel surfaces in plastics processing machines to form deposits

Funding: AiF/FGK

Duration: 01/19 - 12/20

For medium-sized plastics processors, trouble-free and reproducible processes are of fundamental importance for their profitability. A still widespread cause for production interruptions and rejects are especially spots and deposits on tool and machine surfaces. Stippling refers to disturbing inclusions in the plastic material, which can have various causes. If deposits form on melt-conveying machines and tools, there is no material exchange with the flowing melt. As a result, the material degrades and later detaches uncontrollably under the shear forces of the melt flowing over it in the form of spots. The formation of deposits is a phenomenon for which no reliable and reliably effective remedy exists to date. In practice, thin coatings are often applied to machine and tool surfaces to prevent deposits.

Within the framework of two projects already funded by the AiF (IGF 18561 N and 403ZN), the mechanisms of adhesion and coating formation on clean and coated steel surfaces could be systematically investigated experimentally. The focus was particularly on the early phase of adhesion and coating formation of polymer melt.

Within the framework of this new project (20333 N / 2) funded by the AiF, the role of thermomechanical stress and cleaning of melt-bearing components is to be examined. Suitable guidelines and recommendations for action should be derived from this. The guidelines should include the thermomechanical design of the components with regard to permissible deformation, the design of the coating systems with regard to sufficient ductility, as well as recommendations for cleaning processes.