Acura NSX 1994, NSX 1993, NSX 1992, NSX 1991 User Manual

Preparation of Work

Description

• Most monocoque bodies are composed as a single unit by welding together pressed parts made of steel plates which come in a variety of different shapes and sizes. Each part is responsible for displaying a certain strength and durability in order that it may play its role in meeting the functions of the body as a whole.

• The NSX has an all aluminum monocoque body made of the aluminum alloy. Generally speaking, the collision damage of the aluminum alloy body is not very different from that of the steel plate body.

Damage to the exterior of the body can be inspected visually, but where there has been an external impact, it is necessary to inspect the extent of the damage. In some cases, the deformation has spread beyond the actual areas which were in the collision and so this has to be inspected closely.

1175

(46.3 in.)

Camber

Caster

Toe

Wheel t u r n i n g angle

Front wheel alignment:

-0°

2 0 ' ± 3 0 '

8 °

00' ± 4 5 '

Out 3.5 ± 1 mm

Out

(0.14 ± 0 . 04

33°06' ± 2 °

26°34'

in)

Camber

Toe

Rear wheel alignment:

-1°30'±30'

4.0±1 mm (0.16±0

04 in)

Checkpoints

• Accurate Inspection of Damaged Parts (Visual)

Seat Belts Always replace the seat belt if:

1. The belt material is cut, punctured, burned or in any way damaged.

2. The buckle or retractor does not work properly.

3. They were being worn at the time of a collision (also check for damage at the seat belt anchor points).

4. Their condition is questionable.

Front Section:

1. Is there any bending, splitting, denting or other damage to the suspension and its related parts?

2. Is there any deformation of the front bulkhead or radiator core? Have any of the connected sections come apart?

3. Are there any creases or distortion in the front wheelhouse or side frame? Have any of the connected sections come apart?

4. Is there any bending or twisting of the whole front area?

5. Is there any deformation like creases, bulges, or dents in the front pillar, dashboard, floor, etc.?

6. Is there any vertical twisting or misaligned clearance in the door?

7. Is the windshield seal broken?

8. Is there any deformation in the top part of the center pillar?

9. Is there any damage inside the automobile (is there any twisting of the dashboard, or anything irregular with the clearances or sheet-mounting parts) ?

10. Is

there

any

damage

Rear Section:

1. Is there any twisting, bulging or denting of the rear floor and rear bolsters? Have any of the connected sections come apart?

2. Is there any irregular bulging or denting in the rear fender?

3. Is there any distortion in the rear inner panel? Is there any bending and denting in the vicinity of the rear pillar?

4. Is there any distortion or creasing in the rear wheelhouse and arch sections? Have any of th e connected sections come apart?

5. Is there anything irregular in the rear glass seal clearance?

6. Is there any twisting or misalignment of the clearance of the trunk lid opening section?

7. Is there any bending, splitting, denting or other damage to the suspension and its related parts?

8. Is there any deformation oh the rear floor cross member, trunk front panel and damper base? Have any of the connected sections come apart?

9. Is there any oil or water leakage and damage to the engine, transmission or brakes?

10. Is there any irregular noise in the gear changing operation, engine and transmission rotation?

11. Are there any traces of contact between the engine block and the center cross member?

12. Is there any damage to brake or fuel lines, or wire harnesses?

to the

steering

wheel

? Is

there

any

deformation

in the

column

and the

column-mounted parts

Preparation of Work

Correction of the Damaged Area

Set the frame corrector on the car body.

The side sill is flangeless to allow reshaping by pulling it out.

Use the horizontal pinch welds for anchoring the car.

UNDERBODY CLAMPS

Underbody Clamp Specifications:

UNDERBODY CLAMP (Recommended)

Clamp Number

AT-68

ATTACHMENT

Standard type:

C - type

U - type:

Clamp body Side clamp Under clamp

AT-68-AL

AT-68-C

Inside diameter

65 mm

(2.6

in)

AT-68-U

Frame correctors

Dataliner

Car-o-liner

Korek

Auto pole

etc.

U-Base

Celette

Flex-o-liner

etc.

Inside diameter

20 mm

(0.8

in)

Pro-Tec

etc.

1. Apply load to the damage section and pull it out until the section is almost restored to the original shape.

2. Check that the parts of the body they cover have been more or less restored to their original shapes.

5. Decide whether to cut the weld joint parts and replace partially, or whether to replace all the parts. NOTE: Welded parts that can be partially cut and replaced are restricted to those listed in this manual (see

section 4).

NOTE: As work-hardening occurs to the buckled section of the aluminum alloy, it can crack easily. Heat up the damaged section with an acetylene welder and pull it out to

reshape 1184°F (640°C) is the melting point of the alumi-

num alloy. Take care not to overheat it. Watch the heating temperature using a thermopaint, or heat crayon (see page

2-31).

THERMOPAINT

25 mm

(1.0

in)

10 mm

(0.4

in)

6. Cut off and separate the damaged parts. NOTE: When cutting the parts off, take special care

that you do not damage adjacent parts on the automobile.

7. Mold the related parts.

8. Check the reshaped parts for cracks (see page 2-29).

9. Set and tack weld the replacement parts.

NOTE: Temporarily mount the related parts and check

the clearance a nd level differen ces.

10. Weld the replacement parts.

Welding methods (see section 2).

NOTE: Use of th e positioning jig is recommended.

11. Check the welding sections for cracks (see page 2-29).

NOTE: The paint film, which is designed to prevent corrosion caused by moisture, is destroyed around the edges of the locations that have been repaired by

welding. Therefore, in such places and especially in those areas that are not visible, apply another coat of the paint;

refer to the anti-corrosion painting manual. This operation is designed to maintain durability and quality (see

section 7).

3. Check the original position using the body dimensional drawings (see section 6) and the positioning jigs (see

page 1-7).

4. Remove the parts that require replacement.

Preparation of Work

Measurement (Excluding Small Damage)

Whenever possible, make judgements and conclusions based on measurement. Measure the wheel alignment (see page 1-2) to prevent any future trouble like unsymmetrical wear of the tires or catching of the steering wheel.

If there are any deviations, use a tram tracking gauge and measure parts of the body.

POINTER C H O L D E R

REFERENCE S C A L E

ADJUST S C R E W A

POINTER A

If there is any twisting to the body, measure using a frame centering gauge.

Pointer B - short pointer (height adjustment 15 - 290 mm (0.6-1 1.4 in))

- long pointer (height adjustment 185 - 450 mm (7.3 - 17.7 in))

SET R I N G

EXPANDING/CONTRACTING S C A L E

POINTER C

POINTER 4

POINTER B

CLIP

HEIGHT

When measuring body dimensions, use a universal tram gauge.

FRAME

Move within a range of 250 - 1,570 mm (9.8 - 61.8 in)

FRAME

SET SCREW

Positioning J i g ( R ec om m en d ed )

No.

Jig Number

HJ-16-01 HJ-16-02

Description

Front under frame positioning jig Rear under frame positioning jig

Page Reference

4-14 4-53,

57, 60

Aluminum Alloy Repair

Safety Precautions

Precautions f or Ensuring Safet y:

1. Although aluminum is non-toxic, it is lightweight, so fine particles of metal given off by sanding operations tend to float in the air. It is therefore vital that operators protect their lungs and eyes from this dust.

2. Small pieces of aluminum alloy are spattered by MIG welding can be projected over considerable distances. It is therefore important to provide protection not only for the welders operators themselves, but also for the surrounding areas.

3. The sparks generated from the arc during inert gas are welding are very bright and may hurt the eyes if viewed directly. A protective shield for the eyes must therefore be worn at all times when welding.

Use of protective gear to ensure safety:

Work overalls with long sleeves, a cap, and safety shoes must be worn at all times. Depending on the job to be done, protective

goggles, gloves, ear plugs, and a dust-proof mask should also be worn (see page 2-7).

CAUTION:

• When aluminum alloys are heated, they melt without changing color.

Melting temperature

Aluminum alloys: Approx. 1184°F (640°C) (depends on alloy) Steel plate: Approx. 2732°F (1500°C)

• Aluminum alloys can be repaired in virtually the same way as steel sheets, but it is important to have a good grasp of their properties and be thoroughly familiar with their limitations.

• Aluminum alloys tend to overheat during sanding. When they overheat, the metal tends to flake and clog the filing surface of the sanding tool. If a tool with a clogged surface is used, it wi ll leave sc ratch es and marks on th e base metal.

Welding Methods

1. MIG (metal inert gas arc) welding

This type of welding uses consumable electrodes, with electrode wire serving as the electrode. Inert gas is passed through the to rch and welding takes place when an arc is formed between the electrode wir e and the base metal. The electrode wire is supplied automatically.

Although it is dependent on the proficiency of the welder himself, the minimum thickness of weldable aluminum alloy sheets has been 1.6 mm (0.06 in). In most cases the sheets used have been over 3 mm (0.1 in) thick. More recently, welders have

been developed for handling sheets with a thickness of 1 mm (0.04 in) or less.

2. TIG (tungsten inert gas arc) welding

This type of welding uses non-consumable electrodes, with tungsten rods serving as the electrodes. Inert gas is passed through the torch, an arc is formed between the electrode and the base metal, and welding takes place when the heat from the arc melts the base metal and hand-held welding rod. The minimum thickness of aluminum alloy sheets which can be welded is about 0.6 mm (0.02 in), although this method is not suited to heat-treated alloys because there are many thermal effects.

3. Carbon dioxide gas arc welding (metal active gas arc welding)

In place of th e high-cost inert ga s, carbon dioxide gas o r c ar bon dioxide gas mixed with argon gas is e mplo yed as t he shielding gas in the metal active gas arc welders often used today in body s hops. Carbon dioxide gas is not an inert gas in the full sense of the term so these welders are known by the acronym of "MAG" (metal active gas), rather than "MIG."

4. Gas (oxygen, acetylene) welding

Welding or brazing work must not be undertaken using these gases. Since it is hard to concentrate the heat at the welding point, the thermal effects extend to the surrounding area and the strength of the aluminum alloy is reduced. Neither must gas welding be used for brazing since joint strength is too low.

NOTE: Gas welders are used for heating work when aluminum alloys are shaped. (It is necessary to control the upper limit

temperature.)

5. Spot welding

Aluminum alloys cannot be welded using the conventional spot welders which are used in body shops.

The capabilities of spot welders for steel plate are not sufficient for aluminum alloys which have high thermal conductivity.

No matter how long the welding current is allowed to run, the heat escapes to the surrounding areas and the base metal does no.t melt, making welding impossible. It requires a very high current of several tens of thousands of amperes and high pressure to spot-weld an aluminum alloy.

(cont'd)

Aluminum Alloy Repair

Welding Methods (cont'd)

Comparison of spot welding for aluminum alloys and steel plate (one example)

Material

Steel sheeting

Aluminum alloy

NOTE:

• Welding conditions may induce changes in the spot welding current given in the comparison above.

• See page 2-10 for the re-bonding procedure applied when spot-welds on an aluminum alloy body are repaired. MIG welding is used.

• A person proficient at carbon dioxide gas arc welding who has an adequate understanding of the properties of aluminum alloys

will be able to master the technique after practicing for a short while. Practice is important for increasing one's competence.

CAUTION:

• Aluminum alloys melt without changing color when heated.

• It is difficult to judge the melting point when an alloy is heated.

Thickness

1.2 mm

(0.05

in)

Current ( A)

Approx.

9 3 0 0

2 6 , 0 0 0

• Aluminum alloys have a coefficient of thermal expansion which is approximately double that of steel plate and a coefficient of contraction during solidification which is approximately 1.5 times higher. They are therefore subject

to strain more easily and welding cracks (bead cracks and crater cracks) develop.

• Cleaning the welding location greatly affects results. Although the oxide film is destroyed by the cleaning action, it is important for all dirt to be removed, along with any

oil and grease, prior to the welding.

• Tools used for welding aluminum alloys must be kept completely separate from those used for steel plate.

• Use a stainless steel wire brush.

• Use sanding tools which have been reserved especially for use only with aluminum alloys. If the same tools are used for steel plate as w el l, iron deposits will remain on the surface of the aluminum alloy and contaminate welds.)

• Inert gas arc welding is a gas-shielded method and is therefore unfit for working in areas exposed to wind or

breezes. It is important that the flow of the inert gas is not disturbed.

Welders

Performance of Welders:

1. Output current: Approx. 200 A at maximum output

2. Electrode wire diameter: Approx. 0.8~1.2 mm (0.031 (A5356WY) ~0.05 in)

3. Shielding Gas: 100% Argon

• It is an added convenience if the welder can be set to seam, stitch and spot modes.

• A welder which can be used for both aluminum alloy MIG welding and steel plate carbon dioxide gas arc welding simply by changing some parts is economical and ef fi cie nt .

NOTE: Follow the manufacturers' instruction.

REGULATOR

CONTACT TIP

Conditions:

Material thickness unit: mm (i n)

1.6 (0.06)

2.0 (0.08)

2.5

(0.1)

3.0 (0.12)

5.0

(0.2)

ELECTRODE

WIRE

Electrode wire diameter unit: mm (in)

0.8 (0.031)

0.9~1.0 (0.035~0.04)

0.9~1.2 (0.035~0.05)

WELDER

Electrode wire speed (A)

50~70

60~110

80~120

100~140

120~170

GUN

(Torch)

Welding voltage (V)

10.0~11.0

12.0~15.0

13.0~16.0

15.0~18.0

17.0~20.0

Volume 100% argon (L/min)

15.0

17.0

20.0

Aluminum Alloy Repair

Filler Metals

When "filler metal" is mentioned in this text, it refers to welding rods for TIG welding and to electrode wire for MIG welding.

The selection of the filler metal affects the following items relating to the state of the welded joints:

a) Flaws in joints (bead cracks)

b) Strength of joints

c) Toughness of joints (tenacity)

d) Resistance of joints to corrosion

[A5356WY] is the filler metal best suited to aluminum alloys in the 5000 and 6000 series which are used for HONDA

aluminum alloy bodies.

Filler metal storage

Proper storage of filler metals is important for best welding results.

NOTE:

• Store filler metals where they will not become dirty or scratched and where they will be free from contact with oils and greases.

• Use clean gloves when handling filler metals. Seal them in airtight vinyl bags, and store at a constant temperature in a location where they

• Take steps to ensure that the seal cover is not opened until actual use.

will

be dry at all

times. Before sealing

the

electrode wire,

make

sure that

it is

wound properly

on its

spool.

Examples of Repair Tools

Item

Protective equipment

Work

Operator protection 1. Protective goggles 7. Protective apron

2. Cap 8. Welding gloves

3. Earplug 9. Foot protectors

4. Shield for eyes 10. Safety shoes

5. Overalls with long sleeves 11. Work gloves

6. Dust-proof mask 12. Spattering guard

Tools, equipment used

Processing tools

Vehicle body protection

Edge preparation

Heat-resistant

protective cover

SANDPAPER FILES

(cont'd)

Aluminum A l l o y Re pa ir

Examples of Repair Tools (cont'd)

item

Processing t oo l s

Sanding tools

Fixing tools

Work Tools, equipment used

Plug hole drilling

Cleaning

Finishing

Base metal fixing

DRILLING BLADE, DRILL, SPOT CUTTER

ROTARY CUTTER

STAINLESS STEEL WIRE BRUS H

DISC SA NDE R

Disc grinder. Disc sander. Belt sander. Sandpaper.

VISE-GRIPS

PUNCH

SANDPAPER

BELT SANDER

SCREW CLAMP SQUILL VISES

Skin panel shapingShaping tools

NOTE: Use a stainless steel wire brush and sanding tools reserved especially for aluminum alloys. Do not use the same tools

for steel sheet.

HAMMERS DOLLIES/CHISELS

2-8

Grain size for sanding/processing tools and jobs performed.

Tool

Disc grinder

Disc sander

Belt sander

Stainless steel wire brush

NOTE:

• Use a low-speed disc grinder or disc sander.

• If a low-speed air-powered disc grinder is not available, attach an air control valve to reduce grinder speed.

• A double-action sander may also be used.

Cleaning-oxide film removal:

Clean the welding locations throughly (both front and back surfaces).

• Use a wax and grease remover to clean off any dirt, oil or grease.

Disc paper grain size

A36P (grindstone for grinder)

#80~#120 (sanding disc)

#80 or above

• Roughing of weld reinforcement areas.

• Roughing of V-shaped edge preparation.

• Roughing of paint film.

• Sanding of aluminum alloy surface (oxide film)

• Finishing of weld reinforcement areas.

• Finishing of V-shaped edge preparation.

• Sanding of narrow areas.

• Sanding of aluminum alloy surface (oxide film)

Job

• Use a disc sander and stainless steel wire brush to remove paint and oxide films. Use a #80 sanding disc.

NOTE: Do not allow the sanding disc of the disc sander to become clogged. If the disc sander is pressed excessively hard, it will overheat due to friction and the aluminum alloy will tend to peel off, clogging the disc. The alloy surface will be scraped

and scored if a clogged disc is used.

Aluminum Alloy Repair

MIG Welding Conditions

MIG welding can be performed under virtually the same conditions as for the carbon dioxide gas arc welding of steel plate

mentioned previously. The differences are outlined below.

The factors w hich affect deposition at the welding location and serve as the weldi ng conditions fo r carbon dioxide gas arc welding

of steel plates are:

Welding current. Welding voltage (automatically adjusted for HTP MAXI MIG),

Electrode wire speed, Distance between contact tip and base metal, Gun angle. Gun feed speed.

Volume of shielding gas.

NOTE:

Distance between contact

tip and

NOZZLE

base

metal: 8~15

(0.3~0.6

in).

CONTACT TIP

Distance between contact tip and base metal.

ARC

Arc g e n e r a t i o n

As with steel-plate welding, an arc is generated and welding starts once the torch switch is thrown.

• Welding startup is impaired if the electrode wire extends too far out or if the end is spherical. In such cases, cut off the end of the wire with a pair of wire cutters.

Length of wire extension.

ELECTRODE WIRE

CAUTION:

• The torch switch must not be thrown with the electrode wire in contact with the base metal.

• When cutting the end of the electrode wire, point the torch downward and cut near ground level to

protect the eyes from the cut end.

Sound of arc when welding under proper conditions:

With aluminum alloy MIG welding, there is a quiet and continuous humming sound similar to that heard during carbon dioxide gas a r c we l di n g.

A small amount of soot is formed along the bead during MIG welding. This is caused by magnesium contained in the electrode

wires.

1. Differences in welding conditions

When comparing the welding of aluminum alloys and steel plate using the same welder, the thickness range of plates whic h can be welded is less for aluminum alloys. In other words, the welder setting conditions must be adjusted more finely for welding aluminum alloys.

-1. We ldin g current, electrode wire speed Under the same welding current conditions, the electrode wire for aluminum alloys needs to be fed faster than that for steel plates.

-2. Distance between contact tip and base metal As for

steel plate

positioning the gun closer to the surface.

-3. Gun angle

The gun is held perpendicular to the welding surface. It is t ilt ed at a 5~15° angle in the direction of the welding advance. Compared with steel plate welding, the gun angle is slightly more vertical.

welding,

the

distance

ranges

from 8~15

(0.3~0.6

in).

The gas

shielding

effect

enhanced

-4. Direction of gun advance

Either a straight s equence o r back -step can be used wh en fo r we ld in g steel sh eets. With aluminum alloys, however, only the forehand welding method is used.

5°~15°

Direction of advance

-5. Gun travel speed

Welding of aluminum alloys progresses at a much faster rate than for steel plate. The speed increases as the welding progresses.

-6. Volume of shielding gas

About 50% more gas is required than for steel sheet welding.

(cont'd)

Aluminum Alloy Repair

MIG Welding Conditions (cont'd)

2. Nozzle and contact tip

Compared with the carbon dioxide arc welding of steel plates, spattering adheres more readily at the end of the nozzle and the contact tip.

Adhesion of spattering can be reduced by using an anti-spatter compound. This makes it easier to remove spatter as well.

The nozzle and contact tip are subjected to greater wear than with steel plate welding.

3. Electrode wire setting

Since the cable inner liner is made of teflon, be sure not to mark or scratch it.

Use sandpaper to smooth the edge of the end of the electrode wire before feeding it through by hand.

4. Adjustment of electrode wire drive roller tension

Tension is adjusted to a setting less than that for steel plate welding. When the electrode wire is held lightly at the contact tip area and the torch switch is on, the wire is set so that it will slip in the drive roller area. If the tension is set too high, the aluminum alloy electrode wire will be twisted. If it is set too low, the wire speed will not be constant.

NOTE:

The tools used for aluminum alloy welding should be kept completely separate from those used for steel plate.

Use a stainless steel wire brush.

Use sanding tools which have been reserved especially for use with aluminum alloys, (If the same tools are used for steel plate as well, iron deposits will remain on the surface of the aluminum alloy contaminating the welding locations.)

Proper storage of electrode wire is important for best welding results.

Store electrode wires where they will not become dirty or scratched and where they will be fr ee from contact with oils and

greases.

When electrode wire is being used, ensure that it is wound properly on its spool. Use clean gloves to seal wire in airtight vinyl bags and store at a constant temperature in a location where it will be dry at all times.

Take steps to ensure that the covers sealing electrode wire containers are not opened until actual use.

Plug W e l d i n g P r o c e d u r e s

When removing or replacing plates bonded by spot welding, drill through the spot weld nugget and remove. The combinations shown in the figures below apply when plates are to be welded together. Drill the hole when the plates have been removed or drill the prepared hole, and proceed with plug welding.

1. Plate combinations and prepared holes Diameter of drill (spot cutter) when removing plates: 10 mm (3/8") Drill the hole in the new part. Drill diameter: 8~10 mm (5/16~3/8")

Unit: mm (in)

Two stacked plates:

ø10

(3/8)

Two stacked plates:

Three stacked plates:

ø10

(3/8)

Top plate

Bottom plate

Top plate

Bottom plate

Top plate

Middle plate

Bottom plate

Hole drilled in one plate only.

Hole drilled through both plates.

Hole drilled through all three plates.

2. Adherence

Where the plug welding is to be performed, the aluminum alloy plates must adhere together firmly, otherwise the welding will

be defective.

(cont'd)

Aluminum Alloy Repair

Plug W e l d i n g P r o c e d u r e s ( c o n t ' d )

3. Cleaning and sanding Use a wax and grease remover to clean off any dirt, oil or grease prior to welding.

If the aluminum alloy surface is coated with a paint film, use a disc sander and #80 sanding disc to remove the paint.

Use a stainless steel wire brush to burnish the bare surface of the aluminum alloy immediately before the welding.

NOTE: Use a stainless steel wire brush to burnish the bare surface of the aluminum alloy immediately before welding.

Cleaning range

Unit: mm ( in )

When drilling a single-layer hole in two stacked plates:

ø25

( 1. 0)

ø10

(3/8)

015

(0.6)

Oxide film removal by sanding

1. Top surface of top plate.

Prepared hole

2. Bottom surface of top plate.

Prepared hole

Top plate

Bottom plate

Removal of

oxide film

Sand the top and bottom surfaces of the top plate and

the welding surface of the bottom plate.

Remove oxide film by sanding.

Prepared h o le .

25 mm (1.0 in) diameter area on top surface of top plate

centering on plug hole.

15 mm (0.6 in) diameter area on bottom surface of top plate

and welding surface of bottom plate centering on plug hole.

3. Welding surface of bottom plate.

When a hole is to be made through two stacked plates:

Unit: mm (in)

ø10

(3/8)

Top plate

Bottom plate

ø15

(0.6)

ø25

(1.0)

Range of oxide film removal by sanding.

1. Top surface of top plate/bottom surface of bottom plate.

Prepared hole

Removal of oxide film

Sand the top and bottom surfaces of both the top and bottom plates.

25 mm (1.0 in) diameter area on top surface of top plate and bottom surface of bottom plate centering on plug hole.

2. Bottom surface of to p plate/top surface of bottom plate.

Prepared hole

When a hole is to be made through three stacked plates:

Unit: mm (in)

Top plate

Middle p l a t e

Bottom plate

ø10

(3/8)

ø15

(0.6)

ø25

(1.0)

Range of oxide film removal by sanding.

1. Outer surfaces of top and bottom plates.

Prepared hole

15 mm (0.6 in) diameter ar ea on bottom surface of t op plate and top surface of bottom plate centering on plug hole.

Sand both surfaces of the top, middle and bottom plates as shown

to remove oxide film.

25 mm (1.0 in) diameter area on outer surfaces of top and bottom plates centering on plug hole.

Removal of

oxide film

2. Inner surfaces of top and bottom plates, both surface of

middle plate.

Prepared hole

15 mm (0.6 in) diameter area on inner surfaces of top and bottom plates and on both surfaces of middle plate cen tering on plug hole.

(cont'd)

Aluminum Alloy Repair

Plug Welding Procedures (cont'd)

4. Welding Prepared hole diameter: 10 mm (0.4 in)

Plug welding starts from the outside of all weld zones (outside start).

As shown in the figure, outside start welding commences at a position approximately 15 mm (0.6 in) from the weld zone.

Welding start point

Approx. 15 mm (0.6 in)

Advantages of outside start

Penetration is enhanced by the preheating effect accompanying the outside start.

The initial penetration area is clearly visible is the light given off by the arc and working efficiency is improved.

Outside start provides preheating to safeguard the aluminum alloy from inadequate initial penetration.

NOTE: Maintain a stable posture so t hat t he torc h does not move around but is held firmly a nd so that t he weld zone is clearly

visible.

Welding

When drilling a single-layer hole in two stacked plates:

Proceed with welding while aiming at the edge of the hole

where the top and bottom plates meet.

MIG GUN

Protrusion of r ev er se s ide b ead .

NOTE: Melting of 1/3 to 2/3 of the bottom plate is the

adequate for the weld.

With a hole through two stacked plates:

Procedure

Proceed with welding while closely observing the melting condition of the weld zone. Until the operator is experienced in welding, take care not to increase the distance between the torch contact

tip and base metal.

MIG GUN

Welding start point

Ensure adequate penetration as far as the bottom plate.

The reverse side bead on the bottom plate may protrude

in the process. Keep the protrusion to a minimum.

(1) First, proceed from the top.

Proceed with welding while aiming at the joint where the top

and bottom plates meet.

MIG GUN

With a hole through three stacked plates:

Proceed with welding while aiming at the joint where the middle and bottom plates meet.

MIG GUN

The plug hole is filled after welding to a distance

equivalent to about one and half times the entire

circumference.

MIG GUN

Welding start point

The plug hole is filled after welding to a distance equivalent to about twice the entire circumference.

(cont'd)

Aluminum A ll oy R e pa i r

Plug W e l d i n g P roc edu re s (c o n t ' d)

Grinding

Protrusion of reverse side bead. Hole through two stacked plates:

Hole through three stacked plates:

Welding

View from bottom plate

Procedure

(2) Use a disc grinder or disc sander to grind down the area

where the bead on the reverse side protrudes until it is flush with the surface of the bottom plate.

(3) Use a stainless steel wire brush to burnish the surface

where the bead is ground down.

(4) Use an outside start to weld the bottom plate where the

bead is ground down.

Approx. 15 mm (0.6 in)

MIG GUN

Bottom plate side

Top plate side

(5) When welding the bottom surface, position the torch

perpendicularly and weld around the edge of the plug hole.

Butt Welding Procedures

Reduce the clearance as shown in the figure below for butt welding thin plates or sheets. If the clearance is too wide, welding should be performed in the stitch mode.

1. Edge preparation

With plates less than 3 mm (0.12 in) thick:

0~0.5

(0~0.02

in)

max.

Weld with a square edge without special preparation.

Use a smooth-cut file to bring the the edge preparation

surface to a smooth finish.

With plates more than 3 mm (0.12 in) thick:

Proceed with V-shaped edge preparation.

Edge preparation is required for butt welding thick plates, as shown. Use a disc grinder and file (rough-cut or vixen file) for edge preparation. Use a disc sander with #80 sanding disc and a file (smooth-cut) to finish the prepared area.

0~0.5 mm ( 0 ~0 . 02 i n)

max.

0~0.5 m m ( 0 ~ 0 . 0 2 i n ) m a x .

Reverse side beads often occur because of edge preparation in the above figure.

2. Cleaning and sanding Use a wax and grease remover to clean off any dirt, oil or grease prior to welding. If the aluminum alloy surface is coated with a paint film, use disc sander and #80 sanding disc to remove the paint. NOTE: Use a stainless steel wire brush to brush the bare surface of the aluminum alloy. Do this on both the top and bottom

surfaces.

Sanding range

For square edge preparation:

Sand the top to a width of approx. 20 mm (0.8 in) and the bottom t o a width of approx. 10 mm (0.4 in).

20 mm

(0. 8

in)

10 mm

(0. 4

in)

Aluminum Alloy Repair

Butt Welding Procedures (cont'd)

Sanding range

For V-shaped edge preparation:

Sand the top to a width approximately 3 times the width of the edge and the bottom to a width approximately equivalent to the edge.

Width of edge

NOTE: Also sand the edge preparation area.

3. Tack Welding Prior to finish welding, carry out tack welding to prevent strain and enhance joint precision. Weld the plates at several

points with short beads.

NOTE: Use a stainless steel wire brush to clean the tack weld zones prior to finish welding.

The thinner the sheet or plate, the shorter the tack welding pitch and bead.

Avoid tack welding the ends and corners of the base metal.

Since the beads left by tack welding are not ground down afterward, this process should be carried out with the same precision as finish welding.

4. Main welding Maintain a stable posture so that the gun does not move around but is held firmly. The weld zone is clearly visible. Maintain the proper distance between the gun contact ti p and the base metal, and maintain the proper g un angle. Adjust

the gun feed speed while observing penetration.

NOTE:

Aluminum alloys are welded at a higher gun feed speed than steel plate.

Use the forehand welding sequence for the gun advance direction in order to minimize the formation of black soot.

Until the operator is experienced in welding, take care not to increase the distance between the torch contact tip and the base metal.

When welding multiple layers of a thick material, brush the surface of the welded area thoroughly using a stainless steel wire brush after each pass.

5. Greater tr eatme nt

Craters may form when the welding bead is completed. They should be filled properly to avoid defects.

There

when

are two the

ways

welding

bead

treating

completed,

craters.

Either stop

alternatively, switch

the gun and

fill

the

crater

the arc and

then

without

back

switching

again

off the arc

fill

the

suddenly

crater.

CRATER

• MIG GUN

(cont'd)

Aluminum Alloy Repair

Butt welding Procedures (cont'd)

6. How to weld without inducing strain

Tremendous strain results if the base metal is overheated during MIG welding.

When many welding joints have been created, proceed to weld from a location with a minimal degree of freedom. Normally, welding proceeds from the center of the area or center of the joints to the outside.

In direct proportion to the thickness of t he plates, do not conduct lengthy welding operations at one time. Instead, divide the job up into shorter operations, as shown in the figure below.

Preventing strain by sequencing welding work:

Preventing strain by sequencing bead:

Symmetric welding sequence

Welding procedure

When an operator is experienced, the strain can be reduced by increasing the gun feed speed at higher power settings (current). This method reduces the amount of heat transmitted to the base metal.

In the case of thin plates where there is a danger of melt-down, do not weld continuously without stopping but weld short

sections at a time. If the welder is provided with a stitch mode, set to this mode and perform stitch welding.

Skip welding

Overall welding direction

Butt weld zone defects:

The table below shows possible weld zone defects and their causes. Care must be taken to ensure that none of these defects occur. If a defect does deve lop , pinpoint the causes and consider t he appropriate co un te rm ea su re, change the work method, and proceed in a way which will produce stable welding results.

Defect

Bead crack

Crater crack

Appearance

Crack

Excessively high welding current.

Unsuitable filler metal, (welding wire).

Unsuitable crater treatment.

Main cau se s

Crack

Undercut

Poor gun aim. Excessively high welding current. Excessively high welding speed.

Overlap

Insufficient welding current. Excessively low welding speed.

Incomplete penetration Unsuitable edge preparation.

Insufficient welding current. Excessively high welding speed.

Blowhole, pit

Blowhole

Pit

Dirt on base metal (inadequate cleaning). Use steel wire brush. Improper shielding (insufficient shielding gas, strong wind). Moisture on plate surface. Dirt on electrode wire.

(cont'd)

Aluminum Alloy Repair

Butt welding Procedures (cont'd)

Defect Appearance

Unaligned beads Welding wire speed not constant.

Gun travel speed not constant.

Melt-down Excessively high welding current.

Unsuitable edge preparation (too wide).

Formation of soot Poor gun angle.

Improper gun advance (forehand weld sequence). Improper shielding (insufficient shielding gas, strong wind). Dirt on base metal.

Main causes

Fillet W el di ng Procedures

Fillet welding is used on body parts which have different thickness and which need to be strong comparatively. It is important

to have a thorough grasp of what follows.

1. Adherence The aluminum alloy plates where the fillet welding is to be performed must fit together firmly, otherwise, the weld will be defective.

2. Cleaning and sanding Use a wax and grease remover to clean away any dirt, oil or grease prior to welding. If the aluminum alloy surface is coated

with a paint film, use a disc sander with a #80 sanding disc to remove the paint.

NOTE: Use a stainless steel wire brush to burnish the bare surface of the aluminum alloy immediately before welding.

Sanding range:

Sand the top and bottom surfaces of the upper plate and the adhesion surface of the lower plate.

Upper plate

10 mm

(0.4

in)

Weld l i n e

Lower plate

5 mm 10 mm (0.2

Range of oxide film removal by sanding:

Upper plate

5 mm (0.2

in)

5 mm (0.2

in)

10 mm (0.4

in)

(0.4

10 mm

Weld line

in)

(0.4

Sand to a width of about 10 mm (0.4 in) on both the upper and lower plates on the outside of the weld line, and to a width of about 5 mm (0.2 in) from the weld line for the inside surface which will

be overlapped. Also sand the end of the upper

plate.

in)

Lower plate

(cont'd)

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