Short cycle times and maximum flexibility
Short cycle times, high reproducibility and the best possible component quality were the central requirements of LG for selecting the right technology. “With KraussMaffei we have a highly skilled, experienced partner at our side that has supported us from project engineering, development and prototyping all the way to series production,” states Minhee Lee, Vice President at LG Hausys. Since the middle of 2015 the HP-RTM metering machine has been operating at LG Hausys on a press from partner Dieffenbacher to produce advanced structural components for the visible part of automobiles, including a CFRP roof panel.
At the heart of the HP-RTM system is the RimStar Compact 8/4/8 metering system from KraussMaffei. Its main features are its accurate temperature control concept and its precise metering of release agent; it is suitable for processing both polyurethane and epoxy as a matrix material. Two mixing heads of the type MK 10-2K-RTM are used. These prove their value through high durability and exact material discharge, even when there are pressure changes in the mold. “That’s how we provide our customer with maximum flexibility and guarantee a constantly high level of component quality,” says Wolfgang Hinz, Product and Sales Manager at KraussMaffei.
Furthermore, the HP-RTM system delivered to LG Hausys is suitable not only for classic HP-RTM processes, but also for the C-RTM process developed by KraussMaffei. (Compression Resin Transfer Molding) This process is essentially different by having the matrix material fed into the mold when it is slightly open instead of closed. Thus the mold is not completely closed during the feeding. Consequently, the preform is already partially saturated by resin. The feeding is followed by a compression stroke, which presses the resin through the preform, causing it to become completely saturated. As a result, the cavity pressure and the required clamping force drop by about 30 percent. In addition, it is possible to produce with a higher discharge capacity, which in turn reduces the cycle time.
Development pays off in the long term
“The HP-RTM process is extremely complex. Choosing the right matrix materials, molds and technologies is not easy, and requires time and expertise,” says Erich Fries, Manager of the Composites and Surfaces Business Unit at KraussMaffei. Thus KraussMaffei has been working on this project with LG Hausys since the beginning of 2014. Trials at the technical center for lightweight construction in Munich provided support for designing the right components, as did collaboration with development partners Fraunhofer ICT, Alpex (designing the right mold), Dow Chemicals (preparing the epoxy material for the trials), Roding (manufacturing of the preforms) and Dieffenbacher (designing and delivering the presses). The result is a system solution perfectly tailored to the customer’s requirements. “The HP-RTM system was ready for production right after being commissioned, and since then it has been producing components that are free of defects and meet the required quality requirements. Thus the investment and the development time have paid off for us over the long term,” states LG Hausys Vice President Minhee Lee.
Growth market Korea
“Interest in solutions for processing fiber-reinforced plastics that are ready for series production is rapidly increasing also in southeastern Asia. Particularly in Korea we are seeing great interest in HP-RTM systems,” says Fries. “With more than 70 HP-RTM systems on the market worldwide and our experienced support at the KraussMaffei location in Korea, we have the best basis for meeting these requirements.”