Part 1 - Fulvio COPY Flashcards
list 5 advantages of composite materials
- high specific mechanical properties
- flexibility of design options
- corrosion resistance
- excellent fatigue strength
- magnetic and electric conductivity
list 3 disadvantages of composites
- brittle failure mechanisms
- high material costs
- high manufacturing costs
3 advantages of glass FRPs
- high strength
- corrosion resistance
- low cost relative to other composites
4 disadvantages of glass FRPs
- relatively low elastic modulus
- high elongation
- high specific gravity
- sensitivity to abrasion
3 advantages of spray up method
- continuous process
- any materials can be used as mould
- error can be corrected by respraying
5 disadvantages of spray up method
- slow process
- inconsistency
- no control of fibre orientation
- only one sided finish
- environmentally unfriendly
how does the vacuum bagging method of manufacturing PMCs work
- used to make parts stronger
- used for wet lay up, pre preg and spray up methods to remove trapped air - more dense
- thin plastic cover is secured over composite and air is vacuumed out
4 advantages of vacuum bagging
- simple design
- works for any fibre/matrix combo
- cheap mould material
- good quality for cost
3 disadvantages of vacuum bagging
- temp cant exceed 300 deg
- cloth in plastic cover has to be replaced frequently
- time consuming
how does resin transfer moulding (RTM) manufacturing work for PMCs
the preform (precut pieces of reinforcement) is placed in the mould and the mould is closed and thermoset matrix is injected into the mould, it is all cured and ejected`
8 advantages of RTM
- components have good surface finish on both sides
- high fibre volume fraction
- uniformity of thickness
- inserts can be incorporated
- uses only low pressure injection
- easily automated
- low volatile emission
- can use a complex mould
3 disadvatages of RTM
- long curing time
- hard to make intricate parts
- material waste from spill
5 advantages of VARTM
- non autoclave process
- complex parts possible
- no dimensional product limits - less components required - make one big part
- low equipment cost
3 disadvantages to VARTM
- waste of materials
- complexity of resin inlet design
- only one side has good finish
how does resin film infusion (RFI) manufacturing work for PMCs
- epoxy resin is cast in film form and sandwiched between to reinforcement layers
- layers cut to shape and vacuum bagged
- heated so resin flows through thickness of part
4 resin film infusion advantages
- high fibre volumes can be accurately achieved
- high resin mechanical properties
- lower cost than pre-preg
- good health and safety
2 disadvantages of RFI
- requires an oven and vacuum bagging system
- not proven outside of aerospace
4 advantages of filament winding
- using existing process
- easy operation
can make huge parts - can also be used with thermoplastics
3 disadvantages of filament winding
- curing by heat can be problematic
- product shape limeted
- limeted spinning speed
how does process for automatic fibre / tape placement change for thermosets and thermmoplastics
- low pressure for thermoset
- high energy laser beam for thermoplastic
4 advantages of Pultrusion
- automated
- high speed
- versatile cross sectional shape
- can be used with thermoplastics
3 disadvantages of pultrusion
- issues with die
- mainly thermoset matrix
- unidirectional reinforcement
how is a sheet moulding compound made
- resin paste transfers onto moving film carrier
- chopped glass fibres drop onto paste
- second film carrier places another resin layer on top
- rollers compact sheet
- then compression moulded into required shape
2 advantages of Sheet moulding compound
- consistency
- low costs
1 disadvantage of sheetmoulding compound
- low volume fraction
how does compression moulding work
- material preheated and placed in open mould
- pressure applied to force material to contact all areas of mould
4 advantages of compression moulding
- wide range of shapes
- consistent
- simple
- can also be used with thermoplastic polymers
4 disadvantages of Compression Moulding
- high cost of machine
- long time for temp changes
- expensive moulds
- no complex geometries
How does Bulk moulding compound (BMC) work?
thermoset plastic resin blend with fibre reinforcements is formed into a viscous and then injection moulded
2 advantages of bulk mulding compoud
- highest volume fraction for short fibre reinforced composites
- good mech properties
3 disadvantages of BMC
- high temp and pressure
- random fibre orientation
- cant be used for intricate parts
how does injection moulding work?
- pelletized material added to hopper
- gravity fed into heated barrel and screw
- pellets sheared by screw so melt
- material injected into closed mould at high pressure.
- cooled
4 advantages of IM
- multiple materials can be used at once
- small parts possible
- high volume
- can also be used with thermoplastic polymers
3 disadvantages of IM
- high initial tooling and machinery cost
- no complex shaped
- small runs of parts can be costly
applications of IM
automotive, sporting goods, small parts
which manufacturing methods dont require autoclaving
- Resin Transfer Moulding (RTM)
- Vacuum Asisted Resin Transfer Moulding (VARTM)
