composite manufacturing processes
TRANSCRIPT
BY,SANGEETHA B
Composite Manufacturing ProcessesThermoset composites
Short fiber reinforcedContinuous fiber reinforced
Prepreg resin transfer
Thermoplastic compositesCommingleImpregnated
Composite Manufacturing Processes
Processes:Hand Lay-upPre-preg formingPressure moldingVacuum baggingFilament winding
Composite Manufacturing ProcessesProcesses:
PultrusionSpray methodSheet moldingBulk moldingResin transfer molding
Hand lay-up
Hand lay-upAdvantages:
low cost toolsversatile: wide range of products
Disadvantages: time consumingeasy to form air bubbles and disorientation of
fibersinconsistency
Prepreg formingAdvantages:
orientation of fibers can be changedconsistent high productivity
Disadvantages: continuous process needs more
customerslimited shelf lifedelamination
Pressure moldingAdvantages:
wide range of shapes integrate partsconsistency structural stabilityrelatively simple
Disadvantages: high cost of machinetime consuming to heat up, cool down and curingexpensive molds (strong materials required)no intricate parts large volume of products
Vacuum baggingProcess
Vacuum baggingAdvantages:
simple design any fiber/matrix combinationok with cheap mold materialbetter quality for the cost
Disadvantages: cannot be heated up too muchbreeder clothe has to be replaced frequently low pressure (760 mm Hg the most)slowest speed inconsistency
Filament winding
Filament winding productsCompressed air tanks High-pressure CO2 tanks and bottles Water softener systems Rescue air tanks Sail boat mastsCompressed Natural Gas tanks Defense/Aerospace systemsLightpoles
Filament windingAdvantages:
using existing textile processes. quick, easy to handle package.parts can have huge size.
Disadvantages: spinning speed is limited due to resin
penetration and splashing, traveler speed and yarn breakage.
curing by heat is not easy to apply.shape of the products limited (only
cylindrical possible).
Pultrusion
PultrusionAdvantages:
Automated processes. High speed.Versatile cross-sectional shape.Continuous reinforcement.
Disadvantages: Die can be easily messed up.Expensive die.Mainly thermoset matrix.
Spray method
Spray methodAdvantages:
Continuous process Any materials can be used as mold.Error can be corrected by re-spraying.
Disadvantages: Slow.inconsistency.No control of fiber orientation.Only one side finished.Environmental unfriendly.
Sheet molding
Sheet moldingAdvantages
High productivity thus inexpensiveconsistency
Disadvantageslow volume fraction.Only board can be made.
Bulk molding
Bulk moldingAdvantages
Highest volume fraction for short fiber reinforced composites (50%)
Good mechanical propertiesFinish can be appliedInserts and attachments possible
DisadvantagesHigh temperature and high pressure Random fiber orientationCannot be used for intricate partsStaple fibers only.
Resin transfer molding
http://www.plastech.co.uk/Mtrtm.html
Resin transfer molding Advantages
Components will have good surface finish on both sides Selective reinforcement and accurate fiber management is achievable Ability to build-in fiber volume fraction loadings up to 65% Uniformity of thickness and fiber loading, uniform shrinkage Inserts may be incorporated into moldings Tooling costs comparatively low Uses only low pressure injection Low volatile emission during processing Ability to produce near net shape moldings Process can be automated, resulting in higher production rates Ability to mould complex structural and hollow shapes Low resultant voids Ability to achieve from 0.5mm to 90mm laminate thickness
Disadvantages waste some material (spill) curing time long hard for intricate parts