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:

1. Buckle fastening
2. 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

1. Center injection
2. 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

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

1. 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.

 

 

2. Unclogging The Feed Inlet And Exhaust Port Is The Key

 

 

 

Upper Mold

 

 

Lower Mold

 

Lower Mold

 

RTM-gel Coat Preparation

 

Add appropriate amount of curing agent according to the temperature of the day and stir evenly

 

 

Apply the gel coat evenly to the inner surface of the mold without any light transmission, sagging or accumulation.

 

 

RTM-Laying

 

Lay the corresponding mat and cloth on the mold surface according to the product manufacturing process

 

Trim Off Excess Scraps

 

 

RTM-Mold Closing

 

 

Close the laminated lower mold and upper mold and seal and tighten the periphery

 

 

RTM-Injection

Low injection pressure facilitates resin flow, high injection pressure facilitates gas discharge.

Injection temperature and resin viscosity

Low injection temperature and low resin viscosity facilitate resin flow.

Low injection pressure and high injection temperature can be used

 

 

RTM-Curing

 

 

Curing process: gel stage, setting stage (hardening stage), maturation stage (complete curing stage)

Curing control: Control the degree of curing by adjusting the curing agent content and curing temperature in the resin glue

 

RTM-Demolding

 

 

Separate The Upper And Lower Molds

 

 

Separate The Product From The Mold

 

RTM-inspection

 

Check whether the product has defects and whether the mold is damaged

 

 

Products Displacys