Tips for regrinding drill bits
3Passivation treatment
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.
Tips for passivation chamfer (figure 3)
1Please 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)
Back ǰFront
  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
  6 612 1220
Soft steel ȡ -25 -25 -25
H 0.080.12 0.100.15 0.150.20
Hard steel ȡ -25 -25 -25
H 0.050.10 0.080.12 0.100.15

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

  6Under 6 6.18 8.110 10.116
General cast iron

ȡ -10 -10 -10 -10
H 0.030.05 0.040.06 0.050.07 0.060.08
Ductile cast iron ȡ -25 -25 -25 -25
H 0.050.07 0.060.09 0.080.11 0.100.12
AL. Alloy ȡ Not passivation chamfer
H Not passivation chamfer
ȡ =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 20from
grinding wheel (machining of overlapped board uses 15㣩, and then incline the axis of grinding wheel 7