#Blogs: Mould Tools & Jigs
Resin Transfer Molding - RTM
The Resin Transfer Molding (RTM) process is an innovative method for producing fiber-reinforced serial components.
Table of Contents:
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What is the RTM process?
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The procedure of the RTM process
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Advantages of the RTM process for fiber-reinforced components
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Challenges in the RTM process
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Conclusion
What is the RTM process?
In the RTM process, a preform made of fibers is placed into a closed mold and then infiltrated under pressure with a liquid resin system. The curing of the resin results in a strong, lightweight, and structurally sound component. Typical fiber materials used in the RTM process include glass or carbon fibers (CFRP components). Resin systems can consist of epoxy, polyester, or vinyl ester resins, depending on the specific requirements of the final product.

Quelle: Wikipedia
The procedure of the RTM process:
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Preparation of the mold and reinforcement materials: First, the mold is prepared and coated with a release agent to ensure easy demolding. The reinforcing fibers are placed into the mold as mats or fabrics to strengthen the future component.
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Closing the mold and applying vacuum: The mold is closed, and a vacuum is applied to ensure even distribution of the resin and to avoid air inclusions.
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Injection of the resin: The resin is injected into the mold and evenly distributed by the vacuum. It fully impregnates the fiber structure, reaching even hard-to-access areas.
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Curing: After complete infiltration, the resin cures at room temperature or in an oven, depending on the materials used and requirements.
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Demolding and post-processing: After curing, the component is removed from the mold and can be post-processed or painted to prepare it for final use.

Advantages of the RTM process for CFRP components:
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Low costs: The RTM process enables cost-effective production of fiber-reinforced components, as it requires less material and energy compared to other manufacturing methods.
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High strength: By using high-strength fibers like glass or carbon fibers in combination with resin, components with high strength and stiffness can be produced.
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Complex geometries: The RTM process allows for the production of components with complex geometries and thin wall thicknesses that are difficult to achieve with other methods.
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Lightweight: Fiber-reinforced components produced with the RTM process are lighter than comparable metal components, leading to a reduction in the overall product weight.
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Good surface quality: The RTM process can produce components with high-quality surface finishes that require no rework.
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Environmental friendliness: The RTM process is more environmentally friendly than other manufacturing methods, as it generates less waste and consumes less energy.
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Scalability: The RTM process can be applied to produce small to large components, making it particularly flexible in application.
Challenges in the RTM process:
RTM tooling:
Developing suitable tools presents a challenge:
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Precision: Tools must guarantee high contour accuracy and surface quality.
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Stability: They must withstand injection pressure and provide sufficient closing force and stiffness.
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Temperature management: Precise control and even distribution of temperature in the tool are essential for optimal resin curing.
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Gating system: In addition to positioning and designing injection points, improvements can be achieved through gap impregnation or gap injection.
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Sealing: A critical factor for the quality and lifespan of the tools.
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Ventilation: Vent channels must be carefully planned to avoid air inclusions and ensure complete cavity filling.
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Efficiency: Fast opening and closing mechanisms are required to enable short cycle times.
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Integrated sensors: Monitoring pressure, temperature, and resin flow in real-time can help optimize the process and detect errors early.
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Quelle: MICADO | Werkzeug- & Vorrichtungsbau
Automation of resin transfer molding:
The implementation of automation solutions is important for economic efficiency, but also presents challenges:
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Complexity: integrating different process steps into an automated production line can be technically challenging.
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Flexibility: Automated systems must be flexible enough to process different component geometries and sizes

Quelle: Langzauner
Quality assurance
Developing effective quality control methods is crucial:
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Inline inspection: Implementing inspection methods that are directly integrated into the production process can be challenging.
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Defect detection: Reliable detection of defects such as pores or delamination is critical to component quality.
Overcoming these challenges requires careful planning and continuous optimisation of the RTM process. By addressing these points, RTM technology can develop its full potential for the economical series production of high-quality fibre composite components.
Conclusion
The Resin Transfer Moulding process is an innovative and efficient method for the production of fibre-reinforced components, which is characterised above all by its high precision, stability and environmental benefits. The RTM process has a promising future in various high-tech industries thanks to its wide range of possible applications and its ability to optimise weight and strength.