Aircafrt Painting and Finishing

8/11/2019 Aircafrt Painting and Finishing

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UNIVERSITI KUALA LUMPUR MALAYSIAN INSTITUTE OF AVIATION TECHNOLOGY

INSTRUCTOR NOTES.

AIRCAFRT PAINTING AND FINISHING

Introduction.- Purpose- For attractive appearance to the aircraft- For protection to the structure aircraft.

- Finishing and refinishing operation consist of man different materia!s andtechni"ue for app! ing the protective covering.

- #pp! each materia! according to the manufacturer instructions to o$tain the $est possi$!e finish and the greatest possi$!e protection.

Fa$ric finishing processes.- #!though fa$ric-covered aircraft constitute sma!! percentage of the aircraft that

re"uire refinishing% technician shou!d sti!! $e a&are of the refinishing s stemsthat are avai!a$!e.'ope finish.

- One of the easiest to app! and re"uires the !east e(perience and e"uipment todo a satisfactor )o$% $ut has a dra&$ac* of $eing prone to crac*ing.

- +ide se!ection finishing s stem to $eing !imited on! to nitrate or butyrateo!e"

- Ne& s stem more dura$!e and attractive.- To o$tain f!e(i$i!it in a dope fi!m% manufacturers use p!astici,er such as

castor oi!% tricres ! phosphate and vin ! resins.- P!astici,er have tendenc to migrate out of the dope fi!m and after period of

time the fi!m $ecome crac*.- P!astici,er a!so ma*e fa$ric soft enough that can $e a$raded $ sand orattac*ed $ chemica! fumes.

Re)uvenator- If the dopes $ecome $ritt!e crac* $ut the fa$ric is sti!! good% the finish ma $e

re)uvenated.- Re)uvenator is a mi(ture of potent so!vent and p!astici,er.- #pp!ication

Scru$$ed &ith scotch $rite &ith a !ot of &ater.Scru$ it a dampened &ith to!ou! or E to removed an &a(.'r the surface comp!ete! and then spra &ith a re)uvenator&ith some $ut rate dope thinner.

'ifficu!ties &ith dope.- Poor adhesion

Cause $ spra ing nitrate dope over $ut rate dope. Nitrate dope are not strong to penetrate in the $ut rate fi!mformed.Too much a!uminum pigment on the dope.

- /!ushingIf humidit is high enough and temperature drop cause the&ater to condense out of air into the dope fi!m.

To cure the $!ushing is $• 0o&er the re!ative humidit

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INSTRUCTOR NOTES.

• +ait for a da &ith more favora$!e conditions.

- Pinho!esIt happen &hen dope fi!m is e(posed to mush heat or &ind

$!o& across it and a!so atomi,ing air on the spra gun.eans that &hen $u$$!es of the so!vent $rea* through the

surface of the dope &hich has premature! hardened.

- Sag and run.Cause $ spra ing too much dope on the surface and thesurface tension cannot ho!d the materia!s $ac*.The gun move too s!o&! % he!d too c!osed to the &or* and it isnot proper! thinned.

- Orange pee!

Is caused $ surface of the dope dr ing $efore the dope $e!o&surface.Improper spra techni"ues% thinner evaporates to fast.

- Fish e es0oca!i,ed spots &ithin the fi!m of the dope that do not dr .Caused $ &a(% oi! or some si!icone product contaminating thesurface.C!ean the surface &ith to!ou! or E $efore spra ing.

- 'ope roping#pp!ication of dope $ $rush

Caused $ the so!vent evaporating out of dope $efore it f!o&out.To prevent it% use a $it more thinner or a!!o&ed the dope to&arm up if it is coo!.

Po! urethane finish.- o!d t pe 1good to used over meta!.

Not good for fa$ric 1 tendenc to crac* as it f!e(.- Ne& po! urethane 1 use on s nthetic fa$rics- it does not as it f!e(.- For ma*ing repair it ma removed $ sanding them off &ith 234 sandpaper.- The cannot $e softened in the same &a dope &as softened.

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INSTRUCTOR NOTES.

Meta# Fini$%- Stripping

eta! paint used paint stripper.+ear protective e"uipment.'on5t mi( &ith different $rand.#!&a s fo!!o& the manufacturer instruction.

- ProceduresCover or mas*ed a! p!astics% ru$$er and fi$erg!ass part &itha!uminum foi! or po! eth !ene sheet.#pp! &ith $rushUsed p!astic scrapper &ith hot &ater or steam.

+ash &ith &arm &ater% detergent and scoth $rite for removinga!! residues.

- Compound $!astingTo removed o!d finish and corrosion $ sand $!asting'isadvantage 1 ma reduces the meta! thic*ness and stretch

edia $!asting 1 used p!astic materia! to removed o!d finishand surface corrosion &ithout harming the materia!.

- Corrosion remova!Fi!iform corrosion 1caused $ improper! app!ied po! urethanetop coat.

Sand out an corrosion if tit to advance 6deep or $ig7 rep!acedit.Treat &ith acid etchant.#pp!ied conversion coating 6a!odine7#pp! primer.

CHOICE OF FINISHING SYSTEM"- S nthetic ename!s.

Common! for automo$i!es.Can app!ied over ,inc chromate primer Chemica! resistance is nomina! not resistance to a$rasion.8ave good g!oss and do not re"uire ru$$ing.Fo!!o& the manufacturer instruction to mi(ing.

- #cr !ic !ac"uer Use on high vo!ume production !ines 6save times7Primed &ith 2 part &ash primer. #fter dr spra ed &ith acr !ic!ac"uer- eas to app!Fair! resistance to chemica! attac* &eather resistance.Used 9 hour dr ing times $et&een coats.If used retarder% finish shou!d dr over night.

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INSTRUCTOR NOTES.

- Po! urethaneost dura$!e and attractive finish.

Used on high speed and a!titude #:C8ard and chemica!! resistance.Paint stripping has to ta*e some times to remove.Po! urethane mi( &ith cata! st in proportion given $manufacturer.

- #cr !ic urethanes.#cr !ic and urethane are $oth com$ined in one s stem.

Eas to app! as acr !ic.'ura$!e and chemica!! resistance as po! urethane finish.

- Primers#pp!ied to provide good $ond $et&een meta! and cover ;inc chromate is good corrosion resistance.Epo( primer is a!so recommended 6 much $etter 7 ma(imum

protection.+ash primer.

• Popu!ar for production $ecause top coated in short time

6 9 hr 7&ithout the adhere it.• 'o not add acid di!uents &hen mi(ing for the second

coat and &hen it is to $e used over f:g!ass or p!astic.• #pp!ied &ith a fi!m thic*ness not more than 4.<mi!

64.444< IN.7

- S!e&ia# 'ini$%e$ an 'ini$%in( !ro u&t

- 8igh visi$i!it finishes.a*e a:c more visi$!e% $oth on ground and in the air.

#re used for &ing tips% co&!ing% the empennage or co!or $ands.U!tra vio!et a$sor$ing top coat is spra ed he!p to retard fading.

- +rin*!e finishSu$)ects to rough treatmentUsed on instrument pane!% e!ectronic e"uipment% etc.Spra ed on &ith heav coat or recommended $ manufacturer.

- F!at $!ac* !ac"uer Non ref!ective coating for instrument pane! and g!are shie!ds.Can $e $ spra ed gun or aeroso! can spra ed.

- &ing &a!* compoundSpecia! sharp grain sand mi(ed into a tough ename! materia! toform non s!ipper surface.

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INSTRUCTOR NOTES.

#pp! &ith $rush or spra gun using specia! no,,!e for high!a$rasive materia!sThin &ith to!ou! or ename! thinners.

- #cid proof paintFor $atter $o(es meta! and surround area.Used $!ac* aspha!tum materia!s &hich resem$!e tar.Thinned &ith to!ou! and $rush into surface after removed corrosion

- F!oat $ottom compoundfor seap!ane f!oats.Simi!ar to acid proof paint.

- Fue! tan* sea!antSea!ed $ s!oshing &ith sea!er =s!oshing compound5Tan* preparation is made $efore app!ication.

- Seam pasteThic* ,inc chromate materia! &ith organic fi$er em$edded in it.Use for mar*ing &ater proof )oints in sea f!oats and !ea* proof seams infue! tan*s.

- 8igh temperature finishes.Engine ename!.

• 8as pigment that area co!orfast under high temperature.• Thinned &ith regu!ar ename! reduce or to!ou!.

8eat resistant a!uminum paint• To resist temperature at a$out >244 4F• Used on e(haust s stem and heater shrouds.

- Rot inhi$iting sea!er Used to prevent a:c &oods su$)ect to fungus or mi!de&Specia! a!* d resin having ver !o& so!id content in mi(ed &ithfungicida! materia!s.

- Spar vanishPheno!ic modified oi! &hich cures $ o(idation.+ater resistance% not softened $ so!vent.#!so use on e!ectronic components such as circuit $oard.

- Tu$e oi!.

Used to protect tu$u!ar structure in a:c fuse!age% empennage and !andinggear.

- Thinner and reducer.To made pigment or fi!m materia!s !ess viscious for spra ing.Used on! recommended $ manufacturers.

Nitrate dope thinner.• Use to thin nitrate dope% nitrate ce!!u!ose !ac"uer or nitrate

cement./ut rate dope thinner

• Can use on $ut rate and nitrate dope.• Can not use to thin acr !ic.

Retarder

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INSTRUCTOR NOTES.

• 'r ver s!o&! and prevent temperature drop &hich condensesmoisture and cause $ $!ushing

#nti $!ush thinner•

Spra ed over !ast coat.• 8aving s!o&er dr ing so!vents a!!o& each coat more time tof!o& out and from a smoother fi!m.

Ename! reducer.• To &ash do&n a surface to remove &a( after paint stripping

$een used.E

• For genera! purpose c!eaning• Removed a!! &a( and grease

#cetone•

Used as so!vent and c!eaner - Spot putt and sanding surfacesUsed to fi!! crac* or !o& spots in &ood s*ins $efore the are covered&ith fa$ric.

FINIS8IN? E@UIP ENT- Paint shop

E"uipped &ith vapor proof !ight8ave temperature and humidit contro! for optimum spra ingconditions.Protection from over spra &ith po! eth !ene sheeting8as e(haust fans

• P!ace near the f!oor 6 fumes heavier than the air 7• /e!t driven fan &ith motor in an area the vapor &i!! not get

around it.Storage of e"uipment and finish materia!s in approved store.

- #ir supp!#de"uate vo!ume &ith sufficient pressure and free from oi! and &ater.

ost a:c maintenance shop producing pressure a$out >A4 psi. Fi!ter unit and receiver shou!d $e drain ever da .Important 1 pressure for painting is the pressure at the gun it se!f6shou!d have pressure gauge7% ma $e insta!!ed temporar .

- Spra e"uipment< s stems for spra ing !i"uid finishing.#ir spra

• Common! used• Used compress air to atomi,ed the !i"uid

#ir !ess• Using pump to de!iver high pressure for specia! gun.• Used &here !arger area to covered in short period.• Norma!! found on! in spra s shop.

E!ectro static

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INSTRUCTOR NOTES.

• To *ept minimum over spra• ateria! atomi,ed either $ air or $ air!ess pump and high

vo!tage e!ectrica! charge.

- Spra gun

2 t pe• Suction feed guns• Pressure feed guns

/asic different $et&een this 2 is the f!uid tip and air cap.Suction feed guns.

• One "uart cup attached to the gun- used for touch up the painting or other !o& vo!ume &or*.

• F!uid tip stic*s out of air cap to produce !o& pressure.Pressure feed guns

• #ttached to either a pressure cup or pressure pot.• F!uid tip f!ush &ith air cap.• #irf!o& around the tip does not create !o& pressure.• +hen considera$!e vo!ume of materia! to $e spra ed use

pressure feed gun &ith pressure pots.o #vai!a$!e in si,e ho!d from 2->A ga!!on.o A ga!!on pot $eing hand si,e for a:c spra ingo 8ave agitator to *eep materia! mi(ed &hi!e spra ing.o #gitator ma either air driven or turn &ith a cran*.

- Respirator and mas* ost so!vent and thinner are to(ic.

To prevent $reathing fumesFi!ter t pe mas* &i!! remove so!id from air $reath $ut it did not fi!terout fumes.If sta in a paint room ou shou!d &ear air f!o& t pe mas* 6 heavconcentrated fumes 7

- Biscosit measuring cup To dup!icate the viscosit from one $atch to the ne(t.Thin the materia!s and dip viscosit cup into it.Pu!! cup out of !i"uid and chec* time ta*e of the first $rea* appear.Time is dependent upon viscosit of materia!s.

- i(ing e"uipment

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INSTRUCTOR NOTES.

# can of finishing materia! is c!amped into machines &hich sha*e oragitate for >A-24 minutes.Can used hand agitator or agitator driven $ motor 6pneumatic7

Never use an e!ectric motor to driven the agitator 6 prevent fire occur 7- Spra gun and its operation- #d)usting the spra pattern.

ust have correct t pe of gun for the )o$Correct air cap and f!uid tip for the materia! &e are spra ing

ateria! must $e thinned to proper viscosit .#ir !ine is attached to the fitting% $ottom of hand!e.

ateria! supp! is attached to the fitting at the front end of the gun.Open spreader ad)ustment va!ve &hich a!!o&s air to f!o& air to f!o& outof ho!es in &ing port of air cap.# correct! ad)usted spra gun shou!d produced uniform fan shape%spra &ith fan perpendicu!ar to &ing ports.

- Spra pro$!em- Pattern is too heav at either the top or $ottom.

/ui!d up materia! on air capSome ho!e p!ugged up.Correction

• Removed air cap soa* &ith thinner.• 'o not use !oc*ing &ire% it can damage precision ho!es.

- Pattern to heav in center.To much materia! or to thic* Correction

• C!osed f!uid va!ve a $it.• Use !itt!e $it more thinner in materia!.

- Pattern sp!it or to thin in midd!e.

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Aircafrt Painting and Finishing