Tips for regrinding drill bits
(3)Passivation treatment
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Passivation chamfer angle and width depend on the type of drill bit, diameter and material of work piece, make appropriate passivation chamfer according to table 3, table 4.
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Tips for passivation chamfer (figure 3)
 
(1)Please chamfer a expanded arc in R part.
(Drill bit doesn't round Type SC-F, SC-FQ, MX-F, MX-FQ for cast iron aluminum use, please keep the edge unchanged)
 
(2) Please chamfer the edge of cutting edge (rough chamfer) (use #170 electroplated diamond file)
 
(3) Precisely chamfer (use #400-#600diamond manual grinding tool)
Chisel edge regrinding part of Type SC for steel application doesn't need passivation chamfer.
For SX, MX, SS drill bit, their R part, chisel edge regrinding part should have even passivation chamfer
Tips for passivation(figure3)
 
R
SC SX、SS、MX   SC-F、MX-F
SC-FQ、MX-FQ
 
Back 前面Front
  Section A-A  
 
●Type SC-F SC-FQ, MX-F, MX-FQ drill bit's for cast iron, aluminum chisel edge regrinding part should have even passivation chamfer.
●In the diameter range of various drill bits, small-diameter drill bits have small passivation chamfer, and large-diameter chamfer have large passivation chamfer
   
◆.Type SX, SC, MX, and SS for steel application(Chamfer a big arc in R part)
Table 3
  ~φ6 φ6~φ12 φ12~φ20
Soft steel θ° -25° -25° -25°
H 0.08~0.12 0.10~0.15 0.15~0.20
Hard steel θ° -25° -25° -25°
H 0.05~0.10 0.08~0.12 0.10~0.15


◆.Don't chamfer a big arc in R part (keep the edge unchanged)
Table 4

  φ6Under φ6 φ6.1~φ8 φ8.1~φ10 φ10.1~φ16
General cast iron

θ° -10° -10° -10° -10°
H 0.03~0.05 0.04~0.06 0.05~0.07 0.06~0.08
Ductile cast iron θ° -25° -25° -25° -25°
H 0.05~0.07 0.06~0.09 0.08~0.11 0.10~0.12
AL. Alloy θ° Not passivation chamfer
H Not passivation chamfer
θ° =angle H=passivation chamfer width
Till now regrinding is finished, lastly confirm the following points before using
●The difference of cutting edge height is controlled not exceeding 0.02mm
●There is no remaining damage in cutting-edge.

●Had appropriate passivation chamfer
●.Grinding burrs are removed.
 
Regrinding method {Type SD}
●Regrinding of SD drill bit is made as the following orders
(1)Grinding of minor flank
●As shown in the right figure, install the drill bit in the multi-purpose
   grinding machine, shake the worktable to grind.
●Leave the flank of the body beforehand.
●   Lastly make no-sparkle grinding. The difference of cutting-edge
   height shall be controlled not exceeding 0.03mm.
 
Remark:Regarding the details of regrinding, please negotiate through
        another method.
 
   Accept regrinding, recoating order, but must have a certain
   quantity to adjust equipment's power consumption.
 
Use bowl SDC diamond grinding wheel (rough grinding use #120 or so, precise grinding use #400 or so)
   
 
Make cutting-edge and drill bit axis parallel to the worktable, make drill bit axis incline 20°from
grinding wheel (machining of overlapped board uses 15°), and then incline the axis of grinding wheel 7°
 
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