RESIN TRANSFER MOLDING (RTM)
Net-shape, high volume production process
Nammo CS has significant experience in the fabrication of composite structures by resin transfer molding (RTM). Resin transfer molding is a process whereby a composite preform is inserted into a matched metal mold and liquid resin is injected into the tool. Hydrostatic pressure is used to consolidate the preform. This process can provide excellent dimensional control of composite structures. Another feature of RTM is the ability to co-cure foam, metallic inserts, or other pre-cured details into your net shape part.
Nammo CS has worked with customers on the design of RTM structures including the supporting our customers in the following manners:
- Selection of mold materials
- Fabrication of matched metal tools
- Location of injection ports
- Location of thermocouples
- Oven cure vs. Self-heat vs Press cure
- Custom press design and fabrication
- One-piece flow tooling analysis vs. multi-cavity or multi piece molding
- Resin selection including the selection and development of curing agent and accelerators to optimize cycle time
- Cure profile development
- Integration of filament winding, fabric, and prepreg into preforms for subsequent RTM
- Co-cured metal liners: aluminum, copper, and titanium
- Co-Cured metallic and compression molded details
- Structures capable of withstanding 30,000 psi burst
- Pigmented resin blends to meet military color chip specifications
Resin transfer molding (RTM) and other closed volume molding (CVM) processes deliver net-shape parts in fast cycle times, thereby reducing touch labor, machining, and other costs while permitting the integration of additional components such as metallic details. Liquid resin injection in matched metal tooling can yield parts with exceptional thickness control.
A lower cost alternate to RTM is the Vacuum Assisted Resin Transfer Molding (VaRTM) process. VaRTM if often performed on single sided tools to reduce non-recurring cost and uses vacuum to pull resin through the dry preform. This process was developed for boat building and is currently used in the industry for the manufacture of a varerity of advanced structures from airframes to missiles.
RTM, CVM, VaRTM and other out-of-autoclave processes are the next wave in composites technology.