Measures to eliminate faults in brazing operation

Fault description		Main cause	Measure
Fault description		Main cause	Instruction	Illustration
Brazing deformation	Blade (hard alloy) Shank (steel) Status of stress deformation at room temperature after heating, brazing	¡ñ Thickness of blade is smaller than that of shank ¡ñ Big difference between thermal expansion coefficient of blade and shank	¡ñ Thicken blade as much as possible ¡ñ Fill washer ¡ñ Cooling slowly (longer heat preservation time) ¡ñ 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		¡ñ Big difference between thermal expansion coefficient of blade and shank ¡ñ Thickness of blade is smaller than that of shank	¡ñ Use low temperature silver welding ¡ñ Fill washer ¡ñ Cooling slowly (longer heat preservation time) ¡ñ Increase arc radius R of cutter point or chamfer ¡ñ Cut a slot or groove in the shank	Expand blade's square-to-round Blade's square-to-round
Brazing breaking		¡ñ Brazing surface is polluted ¡ñ There is foreign body ¡ñ Brazing is aging ¡ñ Brazing volume is not enough ¡ñ The tightness between base and blade's connecting surface is not good. ¡ñ Brazing surface is too rough	¡ñ Carefully clean brazing surface ¡ñ Use the brazing material that corresponds to the size of brazing urface. ¡ñ Avoid quick heating, ooling slowly (longer heat preservation time) ¡ñ Add appropriate quantity of flux when drilling through the vent. ¡ñ Braze immediately after being rinsed ¡ñ Blade doesn't bend ¡ñ Make good the roughness of brazing surface	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
	¢Ù While using, please wear protective glass, gloves etc (preventing it from contacting skin and mucous membrane part like eyes, nose, mouth etc)
	¢Ú 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)
	¢Û When it is not needed, please treat it as industrial waste.

¢Ù 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

¢Ú 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

¢Û Also can use fluorescent penetrant inspection method and
nesslerization method to check

-174-