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