Measures to eliminate faults in brazing operation

Fault description

Main cause Measure
Instruction Illustration

Blade (hard alloy)

Shank (steel)

Status of stress deformation at room temperature after heating, brazing

● Thickness of blade is smaller    than that of shank
● Big difference between thermal
   expansion coefficient of blade    and shank

● Thicken blade as much as    possible
● Fill washer
● Cooling slowly (longer heat    preservation time)
● Select the shank with thermal    expansion
   coefficient closer to that of    blade

Thickness ratio of blade and shank

Specific ratio of blade thickness and shank width
Brazing crack

● Big difference between thermal
   expansion coefficient of blade    and shank

● Thickness of blade is smaller    than that of shank

● Use low temperature silver welding

● Fill washer
● Cooling slowly
   (longer heat preservation time)
● Increase arc radius R of cutter
   point or chamfer
● Cut a slot or groove in the shank

Expand blade's square-to-round

Blade's square-to-round

● Brazing surface is polluted
● There is foreign body
● Brazing is aging
● Brazing volume is not enough
● The tightness between base and    blade's connecting surface is    not good.
● Brazing surface is too rough

● Carefully clean brazing surface
● Use the brazing material that corresponds
to the size of brazing urface.
● Avoid quick heating, ooling slowly (longer heat preservation time)
● Add appropriate quantity of flux when drilling through the vent.
● Braze immediately after being rinsed
● Blade doesn't bend
● Make good the roughness of brazing

Remove milling mark,
use appropriate blade
The check method of brazing status
Safety attentions in using [SB Flux No. 6]
《SB Solid composition of [SB Flux No. 6]: H3BO3、KHF2、KOH、KBF4》
Because there is acid KHF2 in the composition, it may produce hazardous HF gas
when being heated. While using, please be careful and follow the following points
① While using, please wear protective glass, gloves etc (preventing it from contacting
skin and mucous membrane part like eyes, nose, mouth etc)
② While operating, please use absorption exhaust device that can absorb HF gas.
(Don't inhale harmful gas. Besides, don't discharge HF gas to the air)
③ When it is not needed, please treat it as industrial waste.
① Magnifying glass checking
After being grinded by CBNC or SDC diamond grinding wheel,
use magnifying glass (X 20 times) to observe whether brazing
layer breaks or whether blade cracks
② Knocking checking
For instance, lathe tool, place the lathe tool reversely on
the cutting mat, use sinker to knock the shank to observe
whether the blade falls off
③ Also can use fluorescent penetrant inspection method and
nesslerization method to check