Attentions about brazing materials and brazing operation

◆Importance of brazing operation in carbide tools
　　

Even though the tool that doesn't need regrinding is widespread now, brazing tool
is extensively applied in cutting, mine-construction, and wear-resistant cutters
etc. The brazing operation has great impact on a cutter's performance.
The deformation remained inside when brazing, sometimes are caused because
cracks occur when grinding. Even though no cracks occur when grinding, the
cutter may break sometime at the beginning of being applied due to impact of
inner deformation Brazing operation often needs to consider mutual relations among changes of
characteristics and dynamic change in semi-finished tool and brazing material
when heating, cooling, regrinding after brazing and use characteristics as a tool
◆ Main characteristic factors of brazing operation
（１） Blade and shank (material, form and dimension, profile of connecting part)
（２）Brazing material (type, brazing strength, thickness of brazing layer, flux)
（３）Heating device (flame-absorption type, furnace-insert type, resistance type, high-frequency
（４） Brazing operation (preliminary treatment, heating temperature, heating time, post-treatment)
 

Brazing characteristics
of semi-finished tools
and brazing materials
  
   

Grinding

Application
characteristics
   
Hard alloys (thermal expansion rate: low) Brazing materials
Steel (thermal expansion rate: high)  
When heating   When cooling
How does brazing deformation occur
(Reference)
    

Thermal expansion coefficient of hard alloys: 5～7×10-6 /)

Thermal expansion coefficient of steel: 11～14×10 -6 /K)
◆Flow of brazing operation
Brazing
material
Cutting
Rinsing
Spreading
flux
   
Use general tooth to
cut brazing surface
of the blade
Rinse with brush
in the rinsing lotion
Spread as much as possible in
the surface of brazing material
    
Blade
Rough
grinding
Blasting
Rinsing
Spreading
flux
   

Grind the graphite
etc. Of the blade
surface

Carefully blast on
the brazing surface
of the blade




Rub with steel brush
in the rinsing lotion,
rinse off the oil and mess.

Evenly spread flux
in the brazing surface
of the blade
  
Shank
Countersinking machining
Rinsing
Spreading
flux
   

Mill shank base

Rub with steel brush
in the rinsing lotion,
rinse off the oil and mess

Spread as much as
possible in the cutter
base
        
   
       

SB flux No. 77
or SB metal
fillerNo.77		 　SB flux No. 6 Structure
  Shank  
 
Heating
热700℃～800℃
Try to heat in part, avoid overall
heating to 700℃～800℃
 
Cooling
slowly

Place in lime or straw ash that is
heated to 350～400℃ for 4 hours
to slowly cool
 
Rinsing

Rinse off flux in lukewarm water
of 80～100℃
 
Grinding