Bercella’s Layup process from A to Z
Everything begins with a first step, which is often the most important. Engage the first gear in the gearbox for example, up to the most famous first step of all: that of the first man on the Moon.
The first step in processing of a carbon fiber component is called Layup, and in Bercella it is carried out in the Cutting, Layup and Autoclaves Department.
First of all, it has to be said that here in Bercella we almost exclusively use pre-impregnated materials (prepreg), i.e. carbon fiber already impregnated with resin (epoxy, cyanoester, etc.) from the supplier. Being the resin thermosetting, these materials are subject to deterioration; therefore, to preserve intact its characteristics, they have to be kept in a cold room, with a climate and temperature suitable for its maintenance. The plies are thus stored in rolls and are then cut by CNC cutting machines when needed, according to the indications contained in the nesting file, whose function is to establish the exact cut of the plies with special templates and orientations depending on the type of component that will be made, and the type of material. In fact, the fibers first of all differ for example in the weight, and for the pattern or the filler used (for example aluminum honeycomb or Nomex, Rohacell, etc.)
Once the plies have been cut, they are laid out on the mold following the instructions of the plybook, that is a document drawn up by the Engineering Department, containing all the information for the correct layup of the carbon fiber on the mold, also made in most of the cases in carbon fiber, thus guaranteeing a useful life of about 150 molds, or in metallic materials when a longer useful life is required or for specific process reasons. When the layup is finished, the mold is put under vacuumthanks to a special bag and the use of an aerator cloth, which further facilitates the escape of air. In this way the laminated layers perfectly adhere to the mold, guaranteeing the absence of air bubbles. Now the curing cycle (or polymerization) in an autoclave can begin at certain temperatures, pressures and with certain timing, also established thanks to the important help of the Material Testing Lab of Bercella and its constant improvement to the care of the components’ realization process.
Once the cure cycle is over, the component is extracted from the mold, trimmed, and made available to the Quality Control for an initial inter-phase check, which will control the correctness of the cure cycle and will carry out the first important qualitative surveys. Only at this point the component is declared compliant and takes the name of “laminate” (cured) and can move on to subsequent departments including CNC and Gluing.