1. After the drill bit (such as dry core bit) is used, it should be checked immediately for damages, passivation and other undesirable conditions. If there is, it should be immediately ground and trimmed.
2. When storing, the drill bits (such as dry core bit) should be in proper positions, which is convenient and time-saving for later use and saves the time for searching the drill bits again.
3. During the process of drilling through holes. When the drill bit (such as dry core bit) is about to drill through for a moment, the torque is maximum, so it is necessary to drill slowly with light pressure to prevent the drill bit from being twisted off due to excessive force.
4. Before drilling, the center point must be drilled to prevent the drill bit (such as dry core bit) from slipping and deviating from the center and to guide the drill bit to the correct position.
5. When drilling, attention should be paid to making full use of cutters and removing chips.
6. When drilling cross holes, large-diameter holes should be drilled before small diameter holes.
7. When drilling, the drill bit is broken or suddenly stopped, which may be caused by too fast feed or sudden cooling and heating.
8. Drilling cracks the center of the drill bit, which may be due to too small clearance angle of the drill lip, too fast feed, bit passivation, too high pressure, lack of cooling, and poor clamping of the drill bit or workpiece.
9.  When drilling, the drill bit is broken, which may be caused by too small clearance angle of drill lip or too high drilling speed, large feed or passivation of drill bit and continuous cutting.
10.  The broken cutting edge during drilling may be caused by hard sand holes in the workpiece material or too fast feed, improper selection of drilling speed, and no simultaneous cutting during drilling.
11.  Excessive-diameter drilling hole may be caused by unequal half angle of drill head, deviation of static point, deviation of main shaft, etc.
12. Only one chip is discharged during drilling. The reason may be the two cutting edges are not equal in length or the drill top half angle is not equal.
13. The squeaking sound made during drilling may be due to non-straight drilling or bit passivation.
14. Abnormal changes in cutting properties during drilling may be caused by cutting edge passivation or breakage, etc.