RTM·Resin Transfer Molding Process

Due to the comprehensive requirements of quality, strength, cost, environmental protection, cleanliness, etc., my country’s hand lay-up FRP forming process has begun to transition from open hand lay-up process to closed mold forming process. In recent years, this process has been applied by some companies in related fields such as automotive parts, wind power products, ships and yachts, and has partially or completely replaced the traditional hand lay-up process.

Tooling And Fixture Design Of Mold

In RTM molds, the limit pin is a tool to control the thickness of the product and the fit between the upper and lower molds. At present, it is roughly divided into two types: conical and spherical according to the size of the mold and the scope of application

Conical Stop Pin

Ball Stop Pin

There are usually two ways of fastening:

Buckle fastening
Bolt fastening

Buckle Fastening

Bolt Fastening

Mold Closing Type

Hinged Snap-on Mold Closing

Hinged Buckle Mold Closing

Position Of Injection Port And Exhaust Port

Center injection
Peripheral injection

Peripheral casting can reduce the filling time by more than 60% compared with center casting, and the porosity can be reduced by more than 25%, while also improving certain mechanical properties.

In addition, there are vacuum assistance and filling time control.

Mold Sealing

Sealing is a key step in the entire mold making process. According to the size and structure of the product, it can be roughly divided into the following 7 methods: rectangular sealing, semicircular sealing, mushroom-shaped sealing, semicircular + V-shaped two-way sealing, circular vacuum sealing, circular inflation sealing, semicircular two-way sealing.

Rectangular Sealing

Circular Vacuum Seal

Semicircular + V-shaped Two-way Seal

Introduction to RTM Process

RTM is a composite material production process that first places the reinforced fabric in a mold to form a certain shape, then injects the resin into the mold, impregnates the fiber and solidifies it. It is one of the main molding processes of FRP. Its biggest feature is low pollution and a closed mold operating system. In addition, it is superior to SMC and BMC in terms of product designability, directional enhancement and comprehensive product performance.

RTM-Mold Preparation

Check whether the mold has any defects and use compressed air to clean the impurities on the mold surface. Check whether the design of the injection port and exhaust port is reasonable.