Composite Manufacturing Processes Dr. Yiping Qiu

Composite Manufacturing Processes Thermoset composites Short fiber reinforced Continuous fiber reinforced Prepreg resin transfer Thermoplastic composites Commingle Impregnated

Composite Manufacturing Processes Hand Lay-up Pre-preg forming Pressure molding Vacuum bagging Filament winding

Composite Manufacturing Processes Pultrusion Spray method Sheet molding Bulk molding Resin transfer molding

Hand lay-up

Hand lay-up Advantages: Disadvantages: low cost tools versatile: wide range of products Disadvantages: time consuming easy to form air bubbles and disorientation of fibers inconsistency

Prepreg forming Machine

Prepreg forming

Prepreg forming Advantages: orientation of fibers can be changed consistent high productivity Disadvantages: continuous process needs more customers limited shelf life delamination

Prepreg forming

Pressure molding

Pressure molding Advantages: Disadvantages: wide range of shapes integrate parts consistency structural stability relatively simple Disadvantages: high cost of machine time consuming to heat up, cool down and curing expensive molds (strong materials required) no intricate parts large volume of products

Vacuum bagging Process

Vacuum bagging Advantages: Disadvantages: simple design any fiber/matrix combination ok with cheap mold material better quality for the cost Disadvantages: cannot be heated up too much breeder clothe has to be replaced frequently low pressure (760 mm Hg the most) slowest speed inconsistency

Filament winding

Filament winding

Filament winding

Filament winding products Compressed air tanks High-pressure CO2 tanks and bottles Water softener systems Rescue air tanks Sail boat masts Compressed Natural Gas tanks Defense/Aerospace systems Lightpoles

Filament winding Advantages: Disadvantages: 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

Pultrusion

Pultrusion Advantages: Disadvantages: 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 method Advantages: Disadvantages: 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 molding Advantages Disadvantages High productivity thus inexpensive consistency Disadvantages low volume fraction. Only board can be made.

Bulk molding

Bulk molding Advantages Disadvantages Highest volume fraction for short fiber reinforced composites (50%) Good mechanical properties Finish can be applied Inserts and attachments possible Disadvantages High temperature and high pressure Random fiber orientation Cannot be used for intricate parts Staple 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

Vacuum Assisted Resin Transfer Molding http://www.futuremediacreations.com/technoire/vartm.htm

Vacuum Assisted Resin Transfer Molding Advantages? … Disadvantages?

Filament Placement