Different forms of the RTM process

**Vacuum Assisted Resin Transfer Molding (VARTM)**
In the VARTM process, a vacuum is applied at the air vents (even micro-bubbles trapped between the fibers are removed, thus the trapped bubble content is reduced from about 1% for RTM parts to nearly 0%).

The only difference between this mold structure and the RTM mold is the use of dynamic seals.

These seals are hollow and have the ability to have a vacuum applied when the mold is closed to prevent damage to the seal.

When the mold is closed, a small amount of air pressure is applied inside to ensure a complete seal.

**Light RTM Process**
This process is similar to the VARTM process in that a vacuum is used, but it has a fundamental difference. In this process, the first half of the mold is similar to the NORMAL RTM process, but the second half is thin and transparent so that the resin flow inside the mold can be seen.

Injection is usually done from the perimeter of the mold. This makes the mold filling time approximately three times faster than when injection is done from the center point.

Injection pressure is about 0.5 bar, so perimeter filling slightly overcomes the drawback of long mold filling time (due to low injection pressure).

This process is suitable for very large parts or processes with low production volumes.

**RTM-MIT Process (Multi-Insert Tooling RTM)**
The RTM-MIT process has been recently introduced and is suitable for production volumes higher than 2000 parts per year.

In this process, there are several shells (which are essentially the main molds) that, together with the lower half of the mold, precisely equate to the lower half of a NORMAL RTM mold.

About two-thirds of the process cycle is spent on mold cleaning (the main mold), applying wax and film, gelcoat application, fiber lay-up, and after mold opening, allowing sufficient time for initial curing of parts to prevent deformation.

In the MIT process, all this time is saved.

Therefore, all the shells are cleaned outside the mold, gelcoat is applied to them, and after the gelcoat hardens, fiber lay-up is performed.

Each shell is placed inside the mold, injection is carried out, and after the part gels, the mold is opened and the part is removed from the mold along with the shell.

The resins in this group are specifically for the resin transfer process, characterized by very low viscosity, high flowability, and good fiber wetting ability.
Among the products related to this process are those manufactured at the factory under the brands Kimiya 720, 721, 762, 744, and 746, which boast high global quality standards.

The expert team of Alborz Organic Materials Engineering is at your service at any moment for consultation and product explanations.