JEC COMPOSITES MAGAZINE - Issue #67 - August/September 2011 - 57

a colour match guarantee, UV resistance and high gloss, just as with conventional painting. The process is ideally suited to the production of external parts with high surface finish requirements, parts with high preparing and painting costs, and parts with specific surface finish and structural needs with or without paint. Based on this description, it is easy to understand why the process was named RTM-S: RTM refers to the Resin Transfer Moulding process and the letter S to the term "surface", making reference to "class A" quality surface that the RTM-S aims to achieve. The main challenge of the new concept was to ensure perfect adhesion between thermosetting and thermoplastic resins, as well as dimensional and mechanical stability between the parts considering the different behaviour of the resins under specific conditions, such as exposure to sun, cold and humidity. The development of the RTM-S process was prompted by a number of reasons, including: - Low surface quality of the current composite processes Low surface quality is a general problem in all composite processes, generating high manpower for the preparation for final painting. RTMS, in turn, ensures excellent surface quality (“class A”). - Long cycle times of RTM RTM-S reduces the long cycle times of RTM by eliminating the gelcoat step and offering the possibility of direct mantling over the previouslymoulded thermoplastic shell, so that the cycle only includes the injection, resin catalysis and mould release steps. - High painting preparation and painting process costs

This is currently a general problem in the industry, especially for composite processes, which ultimately involve long lead times in this step. In the new process, the thermoplastic material covers the visible area of parts, so that a remarkable time reduction is expected for this process step, or even its total elimination, when using the thermoplastic multilayer system. - Short lifetime of composite moulds The thermoplastic shell obtained by the new process acts as a protective barrier between the composite mould surface and the resin, significantly reducing mould wear, especially during the resin’s exothermic peak. The life of the composite mould will at least increase threefold. - Limited factory space RTM-S optimizes and saves factory space by eliminating the areas dedicated to the gelcoat step (application booths, stoves) and by reducing the number of moulds, since both production cycle and mould wear are reduced.

Fig.1: Insert for bonded assembly

Process variants RTM-S as a monolithic structure
A monolithic structure is the basic form of the RTM-S concept. Some fixation elements, such as metallic reinforcements, can be bonded to the product’s composite side (“B” side, Fig. 1).

RTM-S with integrated core

This variant integrates a PU core, that improves rigidity and thermo-acoustic insulation properties, and metal inserts for subsequent fastening. The key benefit is the preparation of several processes with advantageous properties in a single injection step. This eliminates the need for further gluing of internal reinforcements and for additional tooling, while reducing labour and the consumption of

No67 August - September 2011 / jec composites magazine finishing materials such as structural adhesives (Fig.2).

Fig.3: RTM as a no-painting concept

Fig.2: RTM-S with integrated core

RTM-S as a no-painting concept
Eliminates the need for painting by replacing the conventional ABS skin by a multilayer thermoplastic system prepared for this purpose, offering a colour match guarantee, UV resistance and high gloss, just as conventional painting (Fig3 & 4).

Technology & Innovations

JEC COMPOSITES MAGAZINE - Issue #67 - August/September 2011

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #67 - August/September 2011