Rubber parts with reproducible curing degree
The mechanical properties of injection-moulded rubber parts are largely determined by the degree of curing. Dielectric analysis (DEA) is a promising method for determining the degree of cure in the mould, and its application to the elastomer injection moulding process has been investigated in the CureDEA project.
Up to now, a qualitative or quantitative determination of the component properties is only carried out after production with a large time lag, during which rejects may have already been produced. The aim of the IGF project CureDEA was thus to investigate the method of dielectric analysis with regard to its ability to monitor the cross-linking process during elastomer injection moulding. To this end, the influence of the process conditions on the dielectric properties was measured. Among others, natural rubber and NBR compounds were investigated in order to cover a broad spectrum of materials. For practical injection moulding tests, the DEA sensor and pressure and temperature sensors were integrated into a mould for cylindrical plates. Using factorial test plans, the dielectric measurements were correlated with the degree of cure.
The measurements show that there is a very high correlation between the permittivity measured in the mould and the degree of cure by means of a swelling test. Process fluctuations were simulated, for example, by varying the injection speed. Based on the DEA, the heating time could be regulated in order to achieve consistent moulded part properties despite varying mass temperatures.
© IKVProject data and funding:
We would like to thank the BMWE for funding the IGF project (funding code 22803 N) and the project partners for their cooperation.
Project duration: 01.07.2023 – 30.06.2025
Promotion:
