The Fiber Patch Placement glossary

As usual in composite technology, also Fiber Patch Placement knows lots of technical terms. Our experts explain the most important ones in this glossary.

  • Anisotropic
    Directional dependence of (material-specific) properties. In case of fiber reinforced composites, the orientation of the fibers determines the degree of the mechanical properties. The material is generally strongly anisotropic. It therefore offers many possibilities to influence and adjust the local product characteristics.
  • Areal weight
    Unit for the area-specific mass of a textile semi-finished product in the unit grams per square meter. Typically used in the composites industry to specify fabrics, scrims or fiber tapes.
    Cevotec’s CAD-CAM software, tailored for a fast product development. Powerful algorithms create an optimized patch laminate from CAD files and generate machine data for SAMBA, allowing for easy robot programming as well as rapid prototyping cycles.
  • Autoclave
    Gas-tight sealable pressure vessel which is used for the thermal treatment of substances in the overpressure range. In the fiber composite industry,  fiber semifinished products pre-impregnated with repoxy resin are pressed and cured. This leads to high fiber volume in the components and good mechanical properties of high-performance components.
  • Butt splice
    Edge to edge joint between two patches in fiber longitudinal orientation.
  • Calander 
    Pressed pair of guiding rollers, which are used for the production of cevoTape and in the SAMBA system for slippage free fiber guiding.
  • Carbon fiber
    Carbon fibers are industrially produced fibers from carbonaceous starting materials, which are converted by carbonation reactions adapted to the raw material in graphite-like carbon. A distinction is made between isotropic and anisotropic types: isotropic fibers have only low strengths and less technical significance, while anisotropic fibers show high strengths and stiffnesses with a low elongation in the axial direction. A carbon fiber has a diameter of about 5-9 microns. Usually, 1,000 to 60,000 filaments are combined to one fiber.
  • CevoPad
    Stack of Patches reinforcing a hole in a component (hole reinforcement). Defined by a center point to rotate patches at their center of gravity. Rotationally symmetrical pattern with radial and tangential patches.
  • Coanda vacuum generator   
    Vacuum generation based on the tendency of gas or liquid flows to “run” along a convex surface instead of being detached from the surface and moving in the original flow direction. By means of the described vector deflection, a direction of air flow from an overpressure region is given a direction and air is sucked in from the environment, whereby the vacuum is generated.
  • Composite structure
    Structure, fully or partially made of composite materials.
  • Conveyor belt 
    Transport system for guiding material. In SAMBA used to transport cut patches.
  • Critical overpap / pull out length
    Minimum length of a single filament necessary for the (almost) complete force transfer between patches.
  • Cutting geometry
    Shape of the cutting edge of a patch.
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  • Fiber
    Threadlike material made of many filaments of an natural or synthetic substance.
  • Fiber architecture
    Fibers arranged in a specific way to give the laminate the desired properties. In common manfacturing processes, stitched non-woven, woven or braided fabrics are common forms of fiber architecture. In Fiber Patch Placement technology, the mechanical performance of products are increased by up to 150% through fiber orientation optimized for complex load paths. Material scrap is reduced by up to 50%, and cycle times are decreased through net shape 3D preforming.
  • Fiber direction (orientation)
    Alignment of a fiber’s longitudinal axis with respect to a reference axis.
  • Fiber Patch Placement (FPP)
    Automated preforming process for the production of carbon fiber composite components in which pieces of fiber tape (patches) are processed additively and directionally.
  • Fiber placement 
    Collective name for manufacturing processes to produce laminates by placing fibers on a tool.
  • Fiber volume content 
    Quantity of fibers in a composite part in relation to the matrix material, expressed as a percentage by volume (see also fiber volume fraction).
  • Filament
    A single fiber of any length and smallest unit of a fiber bundle (roving).
  • FPP
    Abbreviation of Fiber Patch Placement.
  • Gap
    Free space between two subsequent patches in the longitudinal direction of the fiber.
  • Guide curve
    CAD-based entity that describes a patch-based chain. In Fiber Patch Placement the guide curve defines the fiber orientation of a layer/patch zone and is used for generating slave curves within a patch zone.
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  • Impregnation
    Genereal term for wetting the fibers with a matrix material.
  • Impregnation tool
    Mold tool used to keep the dry fiber preform stable during the impregnation process.
  • Infusion
    Closed mold process using only atmospheric pressure to get the resin into the vacuum bagged mold.
  • Injection
    Closed mold process forcing thermoplastic or thermosetting polymers into a mold.
  • Interface
    Surface of or boundary between physically distinguishable constituents of a composite part. Also used to name the surface that separates two parts or laminate layers.
  • Joint axis
    Rotational axis of robots.
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  • Laminate
    Composite material made of two or more bonded layers with the same or different fiber orientation.
  • Laser cutting unit
    Part of SAMBA Series preforming systems to cut the fiber tape into patches. The laser offers the possibility to carry out an almost unlimited number of cuts without wear and maintenance. The laser point is guided by a moving scanner optics.
  • Layer
    In Fiber Patch Placement technology, an entity of sublayers which is defined by a set of parameters, such as patch zone, guide curve.
  • Lay-up  
    Laminate structure consisting of consecutive layers.
  • L-overlap
    Overlap in fiber direction / longitudinal overlap between two patches in two sublayers.
  • Machine vision
    Imaging-based automatic analysis and inspection. In Fiber Patch Placement technology used to controll and record patch-cutting and picking.
  • Matrix
    In a fiber composite material, the (supporting) matrix surrounds the (load bearing) fibers bonded to the matrix by adhesive interactions. Without matrix material, the high specific strength and modulus of the reinforcing fibers are not exploitable. The appropriate combination of fiber and matrix material creates a new construction material.
    Module of CAD-CAM software ARTIST STUDIO. MOTION ARTIST uses the  laminates generated in PATCH ARTIST for automatic offline programming of the SAMBA robots with built-in collision detection and visual process simulation.
  • Net shape
    Due to (near) net shape manufacturing of preforms, Fiber Patch Placement eliminates further forming steps and therefore reduces production costs.
  •  Offset
    Lateral offset of curves (guide curve – slave curve or slave curve – slave curve).
  • Optimal fiber orientation
    Alignment of the fibers along load paths to achieve high mechanical properties while weight is low.
  •  Patch
    A piece cut off a fiber tape with a specified cutting edge at the beginning and at the end as well as two parallel edges in the fiber direction.
    Module of CAD-CAM software ARTIST STUDIO. PATCH ARTIST generates patch-based hich-performance laminates with variable fiber orientation and laminate thickness. Results are visualized, checked and easily modified if necessary.
  • Patch binder 
    Thermally activatable plastic film applied to one side of the fiber tape. The binder stabilizes the tape during processing and handling, and connects the patches after thermal activation on the tool surface or the substrate already laid.
  • Patch chain
    Patches aligned to each other alongside following a curve.
  • Patch gripper 
    Core element of SAMBA Series preforming systems. The form-adaptive patch gripper, developed by Cevotec, passively adapts itself to the complex surfaces of the preforms, thus enabling the exact positioning of the patches on complex geometries while ensuring speed and flexibility and reducing motion control effort.
  • Patch hand-over area
    The area in the machine, within which the patch is transferred from the patch gripper to the preforming tool.
  • Patch laminate
    Laminate constructed of several patches consisting of at least one sublayer.
  • Patch length
    The length of a patch after the cutting process.
  • Patch zone
    A surface area of a part that is to be filled with patches.
  • Pick & place robot
    Multi-axis robot used for Fiber Patch Placement technology, whose main function is to transport an object from one place to another. Currently with Stäubli TP80 the fastest model on the market.
  • Ply
    Layers that make up a stack or laminate.
  • Preform
    In general, assembly of dry fibers and fabric, in Fiber Patch Placement technology three-dimensional near net-shape assembly of patches.
  • Preform gripper
    Standard gripper element, in Fiber Patch Placement based processes used to automatically lift the preform from the mold and feed it to the next production step.
  • Preforming tool
    Mold on which patches are placed to additively build a preform.
  • Prepreg
    Textile fiber-matrix semifinished products pre-impregnated with resins.
  • Pyrometer
    Thermometer for non-contact temperature measurement.
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  • Resin 
    Organic polymer or prepolymer used as an adhesive or a matrix containing the fibrous reinforcement in a composite material.
  • Resin volume content
    Percentage volume content of the resin as matrix in a fiber composite material. In the case of two-component FRP, the RVC is 1-fiber Volume content (FVC). The FVC is the more common characteristic for the description of the volume ratio.
  • Roving
    Bundle or tread of parallelly arranged continuous fibers (filaments) for the production of fiber-reinforced plastics (FRP). Filaments of glass, aramid or carbon are most commonly combined into rovings. Roving is the basis material for the production of fiber tapes, which are processed in an FPP system.
  • RTM
    Injection method for the impregnation of semifinished products in a closed tool for producing fiber-reinforced plastic components.
  •  SAMBA 
    Cevotec’s high-tech preforming system to auromated and quality-controlled produce laminates with complex fiber orientation. SAMBA uses industrial robots to place fiber patches on complex 3D geometries.
  • Scara robot
    Selective Compliance Assembly Robot Arm, an industrial robot whose construction resembles a human arm.
  • Slave curves
    Curves that were built by offsetting the guide curve with a constant offset value in order to cover the patch zone.
  • Spacing
    Space between two neighboring patches along a chain.
  • Stack
    Consists of several (partially) overlapping layers. There can be an overlap between stacks but there doesn’t have to be one.
  • Start point distance
    Distance between the starting point of a guide curve and the first patch position.
  • Stiffness
    The stiffness is a quantity in mechanics. It describes the resistance of a body against elastic deformation by a force or a moment (bending moment or torsion moment, depending on the load). Correspondingly, there are different types of stiffness: strain, bending and torsional stiffness. For more complicated geometries, the separation of the stiffnesses according to load types is often not possible. Thus, a load on tension can also lead to a distortion, e.g. with a helix. The (absolute) stiffness is then a tensor.
    The stiffness of a component depends on the elastic properties of the material, but also on the geometry of the component. It refers to the linear (elastic) range, i.e. only for small deformations, in which the deformation is still proportional to the acting force.
    The stiffness is not to be confused with the strength, which is a measure of the tolerable limit load of a material (ie, the tension at which the elastic deforms into a plastic deformation or breaks the material).
    The reciprocal of stiffness is called resilience.
  • Strength
    The strength of a material describes the maximum load-bearing capacity due to mechanical stress before a failure occurs and is stated as a mechanical stress (force per cross-sectional area). The failure can be an impermissible deformation, in particular a permanent deformation or also a fracture. The strength depends on the material, on the temporal course of the stress (constant, alternating, swelling) and on the type of stress (tension, pressure, bending, shearing).
    Materials with high strength can be loaded with higher stresses than materials with low strength. The former are therefore generally suitable for lightweight construction, in particular materials with a high specific strength (strength per density).
    Stiffness describes the relationship between distortions and mechanical stress, while the hardness of a material describes its resistance to penetrating bodies.
  • Sublayer
    A Sublayer is the smallest entity that is capable of covering the entire patch zone with patches. At least two sublayers are required to ensure load transmission. Several sublayers represent a layer.
  • Sublayer offset position
    In a Fiber Patch Placement-based virtual laminat generation, each sublayer in a layer should be also transversally shifted against each other to increase the mechanical performance. The offset position has to be between zero and the patch width and is a multiple of the patch width divided by the number of sublayer positions. If the number of sublayers is higher than the number of sublayer positions the curve pattern will be repeated after the number of sublayers.
  • Surface
    A CAD-based entity that describes the part surface on which the patch laminate can be generated. It usually extends beyond the layer-boundary to prevent chains from ending inside the patch zone.
  •  Tape / cevoTape
    A spreaded and bindered fiber tape available in various designs. A tape is specified by the filament material, fiber titer, width, areal weight and binder material.
  • Tool manipulation robot
    Articulated robot used for Fiber Patch Placement technology. Currently a Stäubli TX200 with a load capacity of 100 kg, which allows precise guidance even of heavy molds.
  • Unidirectional
    Fibers which follow one direction.
  • VAP 
    Vacuum assisted process, Airbus-patented process, using the properties of modern semipermeable membrane systems in highly developed textile composites to convert the effect of the vacuum into the entire component surface by low-pressure infiltration. This leads to a surface suction of air and gas avoiding air inclusions reliably and efficiently.
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