MIJU - MOLDCAUCHO Project

The general roadmap of Industry 4.0, in which the MOLDCAUCHO project is framed, is to move towards the digitalization of rubber molding processes, to make them more efficient, competitive and environmentally friendly.

Problem

The main focus of the project is to increase the productivity and quality of components manufactured in multi-cavity molds, where possible temperature gradients inside the mold can cause temperature differences between the different cavities, resulting in greater variability in the parts produced.

The objective of this project is the development of a simulation-based tool to support mold design and the selection of optimal process parameters in the manufacture of rubber parts by injection molding.

The ultimate goal and benefit for the company is to have a tool with a dual function available:

• In the mold design phase: the simulation will allow to know the optimal temperature distribution in the mold, as an aid to the location of sensors and the detection of areas in need of implementing local heated zones.
• In the process start-up phase and later in production: the tool will quickly predict the characteristics of the part being manufactured and contribute to the choice of process parameters to achieve optimal manufacturing (vulcanization, cycle time…).

Results

For the development of the project, MIJU selected a use case of a component for the automotive sector with specific functional requirements that required starting the work from the development of a specific rubber mixture for this application. The assembly, belonging to the cooling system, had to slide with minimum friction, but guaranteeing sealing, which required very tight dimensional tolerances.

The chemical compatibility with the coolant, the operating temperature range of -35ºC to 110ºC (with peaks of 130ºC) and the required functional characteristics (85 Sh.A hardness was required) led MIJU to develop an EPDM mixture with a peroxide-based curing system. This mixture resulted in a very high viscosity, which could make it difficult to inject.

Therefore, MIJU, together with MOLWELD, followed a two-stage mold development process. First, working on a prototype mold, basic injection tests were performed and component shrinkage was investigated. This information was the basis for the design of the multi-cavity mold, supported by basic injection simulations.

The final material developed was fully characterized to validate functional and processability requirements . In particular, the material characteristics required for the detailed simulation of the injection process were characterized.