Abstract
The liquid composite molding family (LCM) includes several processes like RTM (“Resin transfer molding”) and VARI (“Vacuum assisted resin infusion”), to satisfy the requirements of each industry. The objectives of recent years in the automotive and aerospace industries tend towards better control of production costs by using of new materials, shorter manufacturing cycles, a higher level of performance and safety and better environmental respect. In the automotive sector, a short cycle time and a lower cost equipment are the most criteria to determine a suitable process, while the quality of the part is the primary parameter for aeronautical process selection. The main objective of this paper is to propose and discuss a new design of LCM mold, allowing at the same time to facilitate the manufacturing process, in particular to reduce the cycle time and to respect the material’s health by obtaining a part with minimum defects. This innovation is achieved by using the TRIZ theory (“Theory of inventive problem solving”), in order to eliminate the contradictions that exist between the requirements of the two sectors.
Highlights
Liquid composite molding (LCM) refers to composite manufacturing processes in which a fibrous preform material is placed into a mold cavity and a thermosetting resin with a relatively low viscosity is impregnated the preform until all empty spaces between the fibers are filled, and cured to create a polymeric composite structure [1]
Due to its capacity to significantly reduce the release of volatile organic compounds (VOCs) to the atmosphere, the LCM manufacturing processes has gained attention compared with current methods of open molding processes
The LCM mold is divided in two parts, the lower part of the mold is always rigid but the upper part is possibly be rigid, like in Resin transfer molding (RTM), CRTM and flexible injection, semi-flexible (RTM-light) or flexible such as in vacuum assisted resin transfer molding (VARTM), VARI and LRI, while the resin can be introduced using a combination of a positive injection pressure, vacuum infusion, and possibly assisted by the compaction force
Summary
Liquid composite molding (LCM) refers to composite manufacturing processes in which a fibrous preform material is placed into a mold cavity and a thermosetting resin with a relatively low viscosity is impregnated the preform until all empty spaces between the fibers are filled, and cured to create a polymeric composite structure [1]. The main disadvantages of the VARTM process are: First, the pressure gradient is limited to one atmospheric pressure so the mold filling is very slow and the filling time increasing proportional to the part’s dimensions [1], along with the low permeability of typical fiber layers often leads the resin to not completely fill the mold cavity before the resin begins to gel To solve these issues many authors and multinational companies have developed the new variants of VARTM, like as SCRIMP [7], FFC method [8] and VIPR [9]. The CRTM needs a high force to displace the moveable upper mold and to better compress the preform, this lead to increase cost equipment and to deform mold walls which influence the part quality Chang proposed another variant of VARTM called Vacuum assisted compression resin transfer molding. This innovation is achieved by using the TRIZ theory (theory of inventive problem solving), in order to solve the contradictions existed between these sectors
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