(WET) HAND LAY-UP(WET) HAND LAY-UP

COMBINING OF REINFORCING FIBER COMBINING OF REINFORCING FIBER AND RESIN AT THE TIME OF PART AND RESIN AT THE TIME OF PART FABRICATIONFABRICATION

REINFORCING FIBERREINFORCING FIBER

E-glass, S-glass, Aramid, Carbon/GraphiteE-glass, S-glass, Aramid, Carbon/Graphite E-glass most common (process inherently produces E-glass most common (process inherently produces

lower "quality" composite laminate due to lack of tight lower "quality" composite laminate due to lack of tight resin content control and low compaction pressure)resin content control and low compaction pressure)

chopped mat materialchopped mat material– consists of randomly oriented chopped fibers or swirled consists of randomly oriented chopped fibers or swirled

continuous fibers which are held together loosely by a continuous fibers which are held together loosely by a binderbinder

– 0.75 oz/sq ft - 3 oz/sq ft0.75 oz/sq ft - 3 oz/sq ft woven fabric material form most commonwoven fabric material form most common

– available on rolls in widths from 36 in. to 60 in. typicallyavailable on rolls in widths from 36 in. to 60 in. typically– terminology and basic weave patterns (refs. terminology and basic weave patterns (refs. 11, , 22, and , and 33))

unidirectional fabricunidirectional fabric– very fine filling (stitching) yarnvery fine filling (stitching) yarn

biaxial fabricbiaxial fabric

RESINSRESINS

polyesterspolyesters vinyl estersvinyl esters epoxiesepoxies

MOLD/TOOL PREPARATIONMOLD/TOOL PREPARATION

procedure to some degree dependent on:procedure to some degree dependent on:– tooling materialtooling material– whether tool is being used in first cycle or whether tool is being used in first cycle or

subsequent cyclesubsequent cycle clean toolclean tool

– scotch brite padscotch brite pad– wipe with a clean cloth dampened with solvent (i.e. wipe with a clean cloth dampened with solvent (i.e.

Acetone)Acetone) mold release agentsmold release agents

– waxes (carnuba-based)waxes (carnuba-based)– spray releasesspray releases– release filmsrelease films– internal releases (added to gel coat or resin system)internal releases (added to gel coat or resin system)

APPLYING A MOLD RELEASE AGENTAPPLYING A MOLD RELEASE AGENT

preheat moldpreheat mold apply release agentapply release agent allow period of time for release agent to "set allow period of time for release agent to "set

up" (for wax) or "flash off"up" (for wax) or "flash off" buff with clean clothbuff with clean cloth repeat application (particularly for first cycle) repeat application (particularly for first cycle)

alternating patternalternating pattern curecure

THE WET LAY-UP PROCESS OFTEN THE WET LAY-UP PROCESS OFTEN BEGINS WITH A GEL COATBEGINS WITH A GEL COAT

typically polyester, mineral filled (clays and typically polyester, mineral filled (clays and carbonates), pigmented (different than mold carbonates), pigmented (different than mold color), non-reinforced layer or coatingcolor), non-reinforced layer or coating

produces decorative, high protective, glossy, produces decorative, high protective, glossy, colored surfacecolored surface

little or no additional finishing requiredlittle or no additional finishing required can paint on, roll on, or spray oncan paint on, roll on, or spray on allow gel coat to set (gel) barely tacky, but allow gel coat to set (gel) barely tacky, but

not release to the fingernot release to the finger

CUTTING THE FABRICCUTTING THE FABRIC

cut desired patterncut desired pattern tools: shears and/or utility knifetools: shears and/or utility knife

WEIGHING OUT THE RESINWEIGHING OUT THE RESIN

weigh out resin components in specified proportions to weigh out resin components in specified proportions to achieve desired resin content (desired fiber volume of achieve desired resin content (desired fiber volume of finished part)finished part)– epoxy curing agents expressed in parts per hundred by epoxy curing agents expressed in parts per hundred by

weight (phr) of epoxy resin or parts by weightweight (phr) of epoxy resin or parts by weight EPON Resin 862/EPI-CURE 3274: 100/42EPON Resin 862/EPI-CURE 3274: 100/42

– resin content expressed as percent by weightresin content expressed as percent by weight epoxy resins typically 25% - 35% by weight (dependent on ability epoxy resins typically 25% - 35% by weight (dependent on ability

to wet out fiber, amount of resin bleeding out during cure, etc.)to wet out fiber, amount of resin bleeding out during cure, etc.) need to account for process wasteneed to account for process waste

– resin bleeding out, remaining on brushes, ...resin bleeding out, remaining on brushes, ...– dependent on size of part (i.e. the smaller the part the greater the dependent on size of part (i.e. the smaller the part the greater the

proportion of process waste)proportion of process waste) draw quantity of resin components, in separate draw quantity of resin components, in separate

containerscontainers thoroughly mix resin components (combine resin into thoroughly mix resin components (combine resin into

curing agent container)curing agent container) tools: containers, stirrerstools: containers, stirrers

RESIN SYSTEM QUANTITIES FOR THE RESIN SYSTEM QUANTITIES FOR THE DEMONSTRATION PARTDEMONSTRATION PART

16, 12 in x 12 in plies of 7781 E-glass cloth16, 12 in x 12 in plies of 7781 E-glass cloth resin system is Shell EPON Resin 862/EPI-CURE resin system is Shell EPON Resin 862/EPI-CURE

32743274– (16 plies)(1 sq ft/ply)(1 sq yd/9 sq ft)(8.95 oz/sq yd)(1 (16 plies)(1 sq ft/ply)(1 sq yd/9 sq ft)(8.95 oz/sq yd)(1

lb/16 oz) = 0.994 lblb/16 oz) = 0.994 lb– x/(x+0.994 lb) = 0.30 (x = lb of resin system)x/(x+0.994 lb) = 0.30 (x = lb of resin system)– x = 0.426 lb (193 gm) of resin systemx = 0.426 lb (193 gm) of resin system– EPON Resin 862 (100/(100 + 42))(0.426 lb) = 0.300 lb EPON Resin 862 (100/(100 + 42))(0.426 lb) = 0.300 lb

(136 gm)(136 gm)– EPI-CURE 3274 (42/(100 + 42))(0.426 lb) = 0.126 lb (57 EPI-CURE 3274 (42/(100 + 42))(0.426 lb) = 0.126 lb (57

gm)gm)– account for process wasteaccount for process waste

APPLY RESIN TO FABRICAPPLY RESIN TO FABRIC

apply resin to fabric on mold surface or, preferably, wet out apply resin to fabric on mold surface or, preferably, wet out fabric with resin on separate surface and transfer to moldfabric with resin on separate surface and transfer to mold

resin may be sprayed, poured or brushed on, and spread with resin may be sprayed, poured or brushed on, and spread with brush and/or squeegeebrush and/or squeegee

applying resin on mold surface prior to laying of fabric applying resin on mold surface prior to laying of fabric facilitates removal of entrapped air during compaction process facilitates removal of entrapped air during compaction process - resin is forced up through the fabric along with the air- resin is forced up through the fabric along with the air

applying resin to fabric on separate surface prevents resin rich applying resin to fabric on separate surface prevents resin rich (female curvature) and resin starved (male curvature) areas(female curvature) and resin starved (male curvature) areas

tools: paint brush, spray equipment, squeegeetools: paint brush, spray equipment, squeegee

COMPACTIONCOMPACTION

resin should be applied and compacted on resin should be applied and compacted on mold surface from the center to the outside mold surface from the center to the outside to facilitate removal of entrapped air, visually to facilitate removal of entrapped air, visually able to see air movingable to see air moving

pressure can be applied with a squeegee pressure can be applied with a squeegee and/or serrated rollerand/or serrated roller

bridging on female contours (radii) must be bridging on female contours (radii) must be avoidedavoided

tools: squeegee, serrated rollerstools: squeegee, serrated rollers

VACUUM BAGGING SEQUENCE VACUUM BAGGING SEQUENCE (VERTICAL BLEED)(VERTICAL BLEED)

PEEL PLYPEEL PLY

placed immediately on top of or under the placed immediately on top of or under the composite laminatecomposite laminate

removed just before bonding or painting removed just before bonding or painting operations to provide clean, bondable operations to provide clean, bondable surfacesurface

woven fabric (nylon, polyester, or fiberglass) woven fabric (nylon, polyester, or fiberglass) treated with nontransferable release agenttreated with nontransferable release agent

SEPARATOR (RELEASE FILM)SEPARATOR (RELEASE FILM)

placed on top of or under the laminate and placed on top of or under the laminate and peel ply (if used)peel ply (if used)

allows volatiles to escape from laminate and allows volatiles to escape from laminate and excess resin to be bled from the laminate excess resin to be bled from the laminate into the bleeder plies during cureinto the bleeder plies during cure

porous or perforatedporous or perforated spacing of perforations or porosity of the spacing of perforations or porosity of the

material determines the amount of resin flow material determines the amount of resin flow from the surface of the laminatefrom the surface of the laminate

BLEEDERBLEEDER

absorb excess resin from the laminate during absorb excess resin from the laminate during cure (resulting in desired fiber volume)cure (resulting in desired fiber volume)

fiberglass fabric or other absorbent materials fiberglass fabric or other absorbent materials or fabrics are usedor fabrics are used

amount of bleeder used is a function ofamount of bleeder used is a function of– absorbency of materialabsorbency of material– resin contentresin content– finished part fiber volume desiredfinished part fiber volume desired

BARRIERBARRIER

between bleeder plies and breather between bleeder plies and breather frequently nonperforated, nonadhering frequently nonperforated, nonadhering

(release) film(release) film resins which produce volatile by-products resins which produce volatile by-products

during cure (must be vented) use a film with during cure (must be vented) use a film with small perforations and large spacing to small perforations and large spacing to prevent the breather from becoming clogged prevent the breather from becoming clogged with resinwith resin

BREATHERBREATHER

on top of barrier film to allow uniform on top of barrier film to allow uniform application of vacuum pressure over the application of vacuum pressure over the laminate and removal of entrapped air or laminate and removal of entrapped air or volatiles during curevolatiles during cure

drapable, loosely woven fabric, or feltdrapable, loosely woven fabric, or felt

CAUL PLATESCAUL PLATES

steel, aluminumsteel, aluminum used to maintain same heating and cooling used to maintain same heating and cooling

rate as moldrate as mold more uniform application of pressuremore uniform application of pressure ensure a smooth, non-wavy surfaceensure a smooth, non-wavy surface

DAMDAM

located peripherally to minimize edge located peripherally to minimize edge bleedingbleeding

may be integral part of tool or rubber, metal may be integral part of tool or rubber, metal bars, etc. bars, etc.

VACUUM BAGGINGVACUUM BAGGING

vacuum bagvacuum bag– used to contain any vacuum pressure appliedused to contain any vacuum pressure applied– application of the vacuum bag extremely criticalapplication of the vacuum bag extremely critical

bag perforation must be prevented bag perforation must be prevented – no sharp edges on toolno sharp edges on tool– properly sealed on edgeproperly sealed on edge

no bridging (requires folds in bag)no bridging (requires folds in bag) folds must be properly made or undesirable wrinkles may folds must be properly made or undesirable wrinkles may

occur in partoccur in part bag sealant tapebag sealant tape vacuum valvesvacuum valves vacuum hosesvacuum hoses vacuum sourcevacuum source

CURINGCURING

follow cure schedule recommended by resin follow cure schedule recommended by resin suppliersupplier

either room temperature or elevated either room temperature or elevated temperature cure resin systemtemperature cure resin system

PREIMPREGNATED MATERIALS PREIMPREGNATED MATERIALS (PREPREGS)(PREPREGS)

reinforcements impregnated with reinforcements impregnated with predetermined amounts of uniformly predetermined amounts of uniformly distributed resindistributed resin

processed to obtain optimum handling processed to obtain optimum handling characteristics and reproducible cured characteristics and reproducible cured laminate propertieslaminate properties

thermoset and thermoplastic resin systemsthermoset and thermoplastic resin systems reinforcing fiberreinforcing fiber

– e-glass, s-glass, aramid, carbon/graphitee-glass, s-glass, aramid, carbon/graphite– unidirectional tape, woven fabricunidirectional tape, woven fabric

HAND LAY-UP OF PREPREGSHAND LAY-UP OF PREPREGS

mold preparationmold preparation ply (prepreg) cutting (and kitting)ply (prepreg) cutting (and kitting) film adhesive may be used against mold surfacefilm adhesive may be used against mold surface ply is laid on mold using hand pressure, squeegee, ply is laid on mold using hand pressure, squeegee,

and/or roller and carrier film is removedand/or roller and carrier film is removed heat gun may be used to improve tackheat gun may be used to improve tack debulking (interim compactions)debulking (interim compactions) process materials and sequence is similar to wet lay-upprocess materials and sequence is similar to wet lay-up curecure

– autoclave (applies heat and pressure)autoclave (applies heat and pressure)– cure cyclecure cycle

temperature and pressuretemperature and pressure ramp ratesramp rates holdsholds