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
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
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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.
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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