Manufacturing composites at industrial standards is a particularly demanding, highly complex process. While metals and metal alloys used for parts production can simply be molten and cooled off inside molds to create a desired component, fiber-reinforced composite elements need to be combined and prepared before the preform procedures and final curing can even begin. That being said, over the last years of development, the procedure has been continually improved upon, now allowing for quick and cost-effective preform manufacturing with the sophisticated Compositence system.
The Process of creating and molding Fiber-reinforced Preforms
There are essentially three types of procedures for composite layups leading up to preform manufacturing: manual, semi automated and automatic. While machine-supported production techniques are quickly becoming the industry standard for the combined advantages of high possible production volumes, low probability of human error and low waste of resources, some manufacturers still rely on outdated manual layup and molding techniques.
Semi automated Layups
This method of preform manufacturing follows multiple steps, making the process significantly more time and resource consuming than machine-supported processes. While there may be differences between individual production techniques, semi-automatic preform manufacturing is usually performed following these steps:
- Raw rovings are woven into fabric
- Non-crimp fabrics are cut to size
- Cut fabrics are stacked
- Stacks are processed into preforms
For a business producing fiber-reinforced composites, the step of weaving rovings into fabric may be discarded simply by investing in a stock of pre-woven non-crimp fabrics or organo sheets, while cutting may be accomplished with machine support. However, the draping and stacking of fabrics is usually performed by hand or semi-automated, making the process more labor-intensive than automated manufacture.
An automatic layup system such as the patented Compositence technology consists of hardware such as robotic servo-arms with specialized fiber extruding heads, as well as software. The software is designed in such a way as to allow users to put in the necessary parameters before preforming begins. Once the parameters are in place, the machine arms follow their instructions precisely.
Aside from the precision of automation, one of the greatest benefits of machine-supported preform manufacture is the possibility of producing finished layups from pure rovings without the need for pre-weaving, cutting and stacking. Two preform manufacturing techniques which use automation to this end are filament winding and Automated Fiber Placement (AFP).
Compositence preform manufacturing machines are capable of processing prepreg materials and unidirectional tapes as well as rovings for resin injection molding.
In filament winding, preforms are created by weaving rovings for injection molding or prepreg materials around a rotating mandrel mold to create hollow three-dimensional shapes. The software systems used for this allow for the individualization of the weaving pattern in precise detail to produce parts with particular structural properties.
AFP, on the other hand, is a particularly quick manufacturing procedure for three-dimensional preform objects. In this process, a robotic arm runs along a mold, laying fibers and epoxy resin directly onto the mold surface. Since the composite material used and the rate at which it is extruded are pre-determined by the software, the process of stacking individual pieces of fabric before preforming can be reduced to a minimum.
Saving Time and Money during the preforming Process
While manual layup can allow for a high degree of detail in preform manufacturing, automatic processes have proven to be more economic and less prone to human error during the critical pre-mold steps. The patented Compositence system uses advanced technology and software in conjunction with an edge fixation system to optimize preform manufacturing, leading to greater turnout volumes of high-quality parts straight out of the molds.