General Brazer's Training Writeup

INTRODUCTION TO BRAZING

By

SUMANT MATHUREM.Phil.(Met)(U.K.),M.I.I.M.,M.I.I.W.

MATHURE GROUP – BRAZER’S TRAINING PROGRAMMEEmail: [email protected] Mobile : 0-98202 91259

mailto:[email protected]

MATHURE GROUP BRAZER'S TRAINING

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SOLDERING – BRAZING – WELDING IT IS A “ONE” FAMILY

SOLDERING 70 C – 450 C

KEYING 90%, DIFF. 10%

BRAZING 500 C – 1100 C

KEYING 10%, DIFF. 90%

WELDING 1100 C – 2500+ C

DIFFUSION 100%

KEYING DIFFUSION


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TYPES OF BRAZING 1. TORCH BRAZING, 2. FURNACE--, 3. DIP --, 4. INDUCTION --, 5. RESISTANCE --, 6. TWIN CARBON ARC --, 7. INFRARED, etc…

550 – 620 C 615- 850 C 710 – 785 C 850 – 920 C 900 – 1050 C 1100C

ALUMINIUM SILVER CuP Gr. BRASS BRONZE Cu

BRAZING ALLOYS & MELTING RANGES

500C 1100C850C


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TORCH BRAZING

NATUREMIXTURECOLOUR

HEATACTION

:::::

OXIDIZINGHIGH OXYGENBLUEHIGH HEATCUTTING

NEUTRALBALANCEDCOLOURLESSMOD-HEATBRAZING

REDUCINGHIGH FUELYELLOWLOW HEATCLEANINGAL. BRAZING

X X X X X

A B C D E

2700 +

2500

2000

1500

APPROX. TIME PERIOD

A – PRE HEAT 1 SECB – PRE HEAT 1.2 SECC - BRAZING 2 SECD – BRAZING 1 SECE – FINISHING 1 SEC.

TOTAL = 6.2 SEC.

M.S TO M.S BRAZING – WITH SILVER BRAZING ALLOY (M.P. 600 TO 850 C)

TEMP


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SAFETY IN TORCH BRAZING

1. GAS CYLINDERS TO BE KEPT IN VERTICAL POSITION & ATLEAST 2M AWAY FROM NAKED FLAMES.

2. USE SOAP WATER TO CHECK – CYLINDER, GAS LINE & ALL FITTINGS.

3. RATIO OF ACETYLENE TO OXY – 1:4 –1:6 BRAZING, 1:10 CUTTING.

4. NORMALLY 0.2 –0.5Kg/sq.cm ACETYLENE, UP TO 3 – 5 OXYGEN.

5. VALVE OPENING & CLOSING SHOULD BE GENTAL.

6. NORMALLY, DO NOT OPEN VALVE MORE THAN ONE FULL TURN.

7. USE SAFETY INSTRUMENTS LIKE – NO RETURN VALVE, BACK FIRE ARRESTER, GAS SAVER, FIRE / SMOKE INDICATORS/ DETECTORS etc.


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JOINT CLEARANCES

0.05 TO 0.07 mm JOINT CLEARANCE

TENSILE

SHEAR

0.002 TO 0.005 INCHES J.C.

T.S V/S J.C. S.S V/S J.C.

GROUP JOINT CLEARANCES SERVICE TEMP.

BA CUZn 0.05 – 0.25 mm 205 – 250 CBA CuP 0.03 – 0.12 mm 150 CBA CuAg 0.05 –0.12 mm 150 – 200 C


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JOINT DESIGNING

TYPE OF JOINTSLAP JOINT

BUTT JOINT

SCARF JOINT

JOINT STRESS

STRESS AT JOINT

DISTRIBUTION OF STRESS

A

B

C

M.S

Cu

M.S

Cu

Cu

M.S

BRAZING OF DISSIMILAR METAL TUBES

HIGH COEFFICIENTOF EXPANSION LIKE COPPER.

LOW COEFFICIENT OFEXPANSION LIKEMILD STEEL.

“C” IS BETTER THAN “B”,“B” IS BETTER THAN “A”


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BRAZING ALLOY – FLUX COMPATIBILITYWETTING ANGLE WITH BASE METAL

WETTING ANGLE ZEROVERY POOR BRAZING.

OR NO BRAZING AT ALL.

WETTING ANGLE 90NOT SO GOOD BRAZING

WETTING ANGLE 180 GOOD BRAZING

REQUIREMENTS OF FLUX

1. DEOXIDIZING PROPERTY2. DIRT & DUST REMOVAL PROPERTY3. BLANKETING PROPERTY4. REDUCTION OF SURFACE TENSION5. INCREASING WETTABILITY OF BRAZING ALLOY6. ACTIVE DURING BRAZING TEMPERATURE7. CLEANING 20 TO 40% MORE THAN APPLIED AREA8. FREE OF SELF OCCLUSIONS / INCLUSIONS.9. LOW SPECIFIC GRAVITY & EASILY DISPALCED BY FILLET.10. WATER SOLUBLE OR DETACHABLE SLAG.11. WITH ADDED pH BUFFER FOR LONGER LIFE12. CHEMICAL COMPATIBILITY IN CASE OF TUBE BRAZING,

e.g. NON-CFC COMPATIBILITY, etc.

FLUX pH TYPE : ACIDIC, NEUTRAL, ALKALINE pH SCALE : 1 TO 6 6.5 TO 7.5 7.5 TO 10

FLUX FORMS : POWDER, PASTE, LIQUID & GAS.


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SOME COMMON STANDARDS AVAILABLE

AMERICAN : AWS – A5.8 – 76BRITISH : 1845INDIAN : IS 2927 – 1964GERMAN : DIN 8513 (ALLOYS), DIN 8511 (FLUX)FRENCH : AFNOR A81- 361 / 362EUROPEAN : EN 1044ISO : ISO 3677SWIDISH : SSARGENTINA : IRAM-IAMAUSTRALIA : ASCANADA : CSARUSSIA : GOST 16130-90CHINA : GB/T 10046 – 2000JAPAN : JIS – Z 3261 / 3264


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BRAZING ALLOYS

PROPERTIES SILVER COPPER BRASS

1. MELTING RANGE 600 C TO 750 C 700 C TO 850 C 850 C TO 950 C

2. SUITABLE FOR EXCEPT ALUMINIUM Cu TO Cu & Cu to Brass M.S. TO M.S / Cu ALMOST ALL METALS WITH GAS FLUX / FLUX BIG SECTIONS

3. ALLOY RANGE MORE THAN 20 ALLOYS ONLY 5 TO 6 ALLOYS 2 OR 3 ALLOYS

4. STRENGTH EXCELLENT MODERATE / POOR VERY GOOD

5. DUCTILITY EXCELLENT POOR / MODERATE GOOD

6. PENETRATION 43% EXCELLENT 5% & 14% V.GOOD MODERATE 35% VERY GOOD 2% GOOD 30% TO 25% GOOD 0% MODERATE

7. COMMON USAGE ALMOST EVERY WHERE REFRIGERATION AUTOMOBILE, TOOLS ELECTRICAL LOW VALUE BRAZING


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CuP Group Silver Group - Specials Bronze Gr.

CP-20 Silloy-25 S13LCD Nickel-B

CP-22 Silloy-30 S20LCD F-Bronze

CP-27 Silloy-35 S30LCD M-Bronze

Silloy 2 Silloy-39 S38LCD G-Bronze

Silloy 3 Silloy-43 S46LCD SB64

Silloy 5 Silloy-50 S50Ni SBN-54

Silloy 15 Silloy-60 S55Sn

Silloy-72 S70Ni

Silloy-98

MATHURE’S SPECIAL BRAZING ALLOY PRODUCTS

Available in the form of rods, rings, coils & strips.


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PROPERTY 2% ALLOY 5% ALLOY 30% ALLOY 43% ALLOY

MELTING 700 – 770 C 690 – 770 C 640 – 680 C 605 – 615 C

T.S. Kg/mm2 APPX 23 – 25 APPX 23 –25 APPX 25-30 APPX 25-30

S.S. Kg/mm2 APPX 16 – 18 APPX 16 – 18 APPX 17-20 APPX 17-20

SPECIFIC Grv. 8.0 Gm/cc 8.1 Gm/cc 9.0 Gm/cc 9.3 Gm/cc

FLUIDITY MODERATE MODERATE FAST VERY FAST

USE FOR Cu-Cu Cu-Cu Cu-Cu Cu-Cu

Cu-Brass Cu-Brass Cu-Brass Cu-Brass

Cu-M.S. Cu-M.S.

M.S.-M.S. M.S.-M.S.

Brass-M.S. Brass-M.S.

PRICE (Aprox) Rs.410/KG Rs. 730/KG Rs. 3300/KG Rs. 4300/KG

ALLOY COMPARISON CHART


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GAS FLUX

GAS FLUX OR VAPOUR FLUX IS A COMPARITIVELY NEW CONCEPT, WHERE FLUX IS BEING INTRODUCED ON TO THE JOINT THROUGH FLAME. THIS CAN BE USED FOR ALL BRAZING APPLICATIONS WHERETORCH BRAZING IS USED, AS IT KEEPS JOINT FREE FROM OXIDATION. HOWEVER, IT HAS SPECIALADVANTAGE FOR COPPER BRAZING & M.S. BRAZING.

OXYGEN

L.P.G. OR ACETYL GAS GAS FLUX &GAS FLUX UNIT

FUEL GAS + FLUX BURNINGIN BRIGHT GREEN COLOUR

THIS SYSTEM INCREASES THE JOINT STRENGTH, IT HAS NO-CLEAN RESIDUE, & IT IS EASILY ADOPTED ON EXISTING SYSTEM JUST BY ADDING “GAS FLUX UNIT” G.F.U. AS SHOWN ABOVE.

LIQUIMUX


14

Silver flux Bronze flux Aluminium flux

Solder flux

Silmux – G Bromux – R Alumux – B Solmux-R

Silmux – T Bromux – L5 Alumux - W Solmux – J

Silmux - GT Bromux – LO Solmux – L

Bromux – Gr. Spatmux Solmux – P

Liquimux Copmux Waxmux Solmux - NC

MATHURE’S SPECIAL BRAZING FLUXES

Available in the form of Powder, Paste & Liquid.


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JOINT PREPARATION

1. DEGREASING OF JOINING COMPONENTS,2. DEBURRING OF JOINING COMPONENTS, 3. MAINTAINING CORRECT & PARALLEL GAP BETWEEN THE JOINTS 4. INSERTION TILL CORRECT JOINT LENGTH5. PRE FLUXING OF JOINTS

CARE TO BE TAKEN FOR

1. PROPER DEGREASING COMPOUND / COMPATIBILITY TEST REQUIRED.2. PROPER DEBURRING MEDIA / RESIDUAL TEST REQUIRED3. AS PER ENGINEERING DRAWING / Q.C. CHECK ON ALL COMPONENTS4. MARK ON COMPONENT OR FIXTURE REQUIRED FOR ASSURANCE.5. USE OF BRUSH & CORRECT VISCOSITY OF PASTE FLUX IS REQUIRED.

NOTE: More stressed joints-more chances of Fatigue crack.


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A B C D E

A = BURRSB = INSSUFICIENT INSURTIONC = PARALLEL GAP & SUFFICIENT INSERTION.D = TILTED / TENSE JOINTE = ONE SIDE SHIFT – BIG GAPS

WHICH IS THE BETTER JOINT ?


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60 – 70 % 40 – 30 %BRAZING

PREHEATING

A B

C

BRAZING PROCESS


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POST BRAZING 1. BRAZED AREA MUST BE CLEANED USING WARM WATER2. WIRE BRUSH, ABBRESSIVE CLOTHS MAY BE USED FOR CLEANING HARD MASSES OF FLUX RESIDUE.3. INCREASED SOAKING TIME, HELPS TO EASE CLEANING.4. IN CASE OF SOME PRODUCTS, WATER JET SPARY, STEAMING, DIPPING IN TANKS, VIBRATION etc., IS APPLIED TO CLEAN THE RESIDUAL FLUX.5. RESIDUES CAN CAUSE a) CORROSION IN & AROUND BRAZED AREA b) DIFFICULTY IN PAINTING, FILMING etc. c) BAD ESTHETICS OF THE JOINT d) DIFFICULTIES IN REWORK AS REBRAZING. BRAZING AREA MUST BE FREE FROM FLUX RESIDUE FOR LONGER LIFE OF BRAZED JOINT.


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INSPECTION OF BRAZED JOINTS

A B C DGOOD FILLET LESS FILLET POROSITY CHOKE OVER FLOW


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LEAK DETECTION METHODS

1. SOAP TEST : IN THIS DILUTE SOAP SOLUTION IS USED & APPLIED OVER THE JOINT, IF IT IS A LEAK THEN SOAP BUBBLES APPEAR ON THE SURFACE.2. HELLIUM LEAK TEST : IT IS MODERN TESTING METHOD, WHERE LEAKED GAS IS DETECTED BY A PROBE

PRECAUTIONS: IN CASE OF HELLIUM LEAK TEST, IT IS NECESSARY TO USE SOME CLIPING METHODS TO CONFIND LEAKED GAS AT THAT POINT, SO THAT THEACCURACY IN THE METHOD IS MAINTAINED.


21

AUTO BRAZING

PRE FORMS & PRE FLUX

RINGS FOILS PASTE GAS FLUX

AUTO HEATING

TORCHES INDUCTION FURNACE

AUTO FEED

CONVEYOR BATCH TRAY


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HOW MANY STATIONS TO GET 100% YES ?

1

2

1

1

2

1

2

1

2

3

YN

PRE FLUXING BRAZING OPERATION

ASSEMBLY SOAKING & CLEANING

INSPECTION / CUSTOMER ASSURANCE LAB (CAL)

REWORK


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DATA COLLECTION & STATISTICALS DAILY REPORT

BRAZER’S IDENTITY JOINT IDENTITY TOTAL JOINTS TOTAL LEAKS

LEAK REPORT

JOINT IDENTITY LEAK % LEAKAGES MAY BE DUE TO

BRAZING ROD FLUX DESIGN ASSEMBLY BASE METAL HEAT TIME MAN OTHER


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4 M TECHNIQUES

MAN MATERIAL METHOD MACHINE

OPERATOR BRAZING RODSBRAZING FLUX

BASE METALRINGS / PREFORMS

ASSEMBLING METHODDESIGNING FLAWS

OPERATOR’S POSITIONAPPLICATION OF RODAPPLICATION OF FLUX

HEATING METHODPOSITIONING OF JOB

HANDLING OF JOBSEQUENCE OF WORKPREPARATION OF JOB

POST BRAZING HANDLINGPOST BRAZING CLEANING

TESTING METHODSPACKAGING METHODS

…….Etc.,

HEATING SOURCEJIGS & TOOLSCONVEYORS

WARN OUT PARTSALL M/C RELATED

PROBLEMSEtc.


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COMMON FAULTS IN BRAZING

1. POROSITY – DUE TO Zn, Cd, P BASE ALLOYS2. SLIDES / HAIR LINE CRACKS IN BRAZING JOINTS3. HAZ CRACKING OR “C”, “H” PENETRATION HARDNING.

COMMON REASONS FOR FAULTS IN BRAZING

1. JOB , FLAME & ROD FEED POSITIONING2. VIBRATION DURING BRAZING3. IMMEDIATE SHAKING OF JOB AFTER BRAZING4. VARIATION IN BRAZING ROD SIZE / RING SIZE5. IMPROPER OR INSUFFICIENT FLUXING6. IMPROPER OR INSUFFICIENT HEATING 7. STRESSED JOINTS8. JOINT CLEARANCES, JOINT ASSEMBLING


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• The molecular structure is aerodynamic. Hence it leaks thro’ very minute pin holes.

• Easy to break forming HF acid & some hydrocarbons

• Vigorous reactivity with Cl, SO4, acids & alkalis, few oils.

HF

C

1,1,1,2,Tetrafluoro Ethane.

• The molecular structure is bulky. Hence it does not leaks thro’ very minute pin holes.

• Molecules are not so easy to break.

• Reactivity with Cl, SO4, acids & alkalis, is average

F

Cl

C

HR12 R22

R134a V/S R22 , R12


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GOLDEN RULE OF BRAZING

ETAL TO BE BRAZED MUST BE CLEANED

LLOW PROPER JOINT CLEARANCE

RANSFER OF HEAT MUST BE THROUGH BASE METAL

EATING MUST BE UNIFORM ALL OVER THE JOINT

SE PROPER BRAZING ALLOY & BRAZING FLUX

ECAP THE FLUX CONTAINER AFTER USE

NSURE HYGINE CARE BY USING GLASSES, MASKS….

MM AA TT HH UU RR EE

MM AA TT HH UU RR EE

General Brazer's Training Writeup

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