Technology page is shared the experience of technical talent in field of drill bit grinder, help you to resolve the technical difficulties, and makes you into a specialist of drill bit re-grinder.
Drill Bit
The drill bit is the best cutting tool for grinding.
The design should consider the need for grinding.
For preprocessing or general hole accuracy, degree of the drill bit grinding is worn at most 20 times. For high precision drilling bit, it can be sharpened 5 times.
In the process of metal cutting, twist drill cuts the metal layer on the workpiece, at the same time, the workpiece and chips acts on the twist drill, causing the twist drill wear off. Normal wear off is inevitable, but abnormal wear is not acceptable. Such as abnormal wear on corner part of twist drill, Now, PURROS Machinery will enumerate these questions, and how to solve them.
In production, chipping of corner edge twist drill is happened many times. Because of drill material, loose jig, uneven hardness of workpiece material, unsuitable feed speed, unsuitable coolant, relief angle too small, or exhausted bit, etc.
Situation 1: 
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During drilling operation, problems with drills broken are often encountered. Now, PURROS Machinery lists the solutions of drill breakage as below:
Drill Breakage and Solutions
| Type of Cutting Tools | H12 | H11 | H10 | H9 | H8 | H7 | H6 | H5 |
| HHS | x | x | ||||||
| HHSEnlarging Drill | x | x | ||||||
| Spot Weld Carbide Drill | x | x | ||||||
| Solid Carbide Drill | x | x | x | |||||
| Solid Carbide Straight Flute Drill | x | x | ||||||
| Solid Carbide 3-flute Drill | x | x | ||||||
| Gun Drill | x | x | x | |||||
| Reamer | x | x | x | |||||
| PCD Enlarging Drill | x | x | ||||||
| PCD Reamer | x | x |
(Made by: Purros Machinery Co., Ltd.)
Negative Chamfering
Step 1: Sharpening the major flank face, at the same time, sharpening lip relief angle;
Step 2: Sharpening the minor flank face, at the same time, sharpening end relief angle;
Step 3: Sharpening the fake face, at the same time, sharpening point angle;
Step 4: Sharpening remained faces and the tip;
Now, PURROS Machinery takes the rough grinding carbide alloy cutter as an example, to illustrate the method of cutting tool sharpening.
1. Rough sharpening the major flank face and the minor flank face, at the same time, major angle of declination, major lip relief angle, minor angle of declination, and minor lip relief angle also has sharpened. The angle of major lip relief angle and minor lip relief angle by rough sharpening should be bigger than requested. View Figure:
Lip Relief Angle of Shank
(a) Lip Relief Angle, behind the major flank face of shank
(b) Lip Relief Angle, behind the minor flank face of shank
2. Rough Sharpening Rake Face: Rake Face and Flute are sharpened at the same time, before flute is sharpened, used the end face of grinding wheel to rough sharpen, to obtain the necessary angle and surface roughness.
3. Sharpening Flute: Flute can be sharpened by edge of flat grinding wheel, as Figure shows the sharpening method. Generally, the position of rough sharpening should be began half of between flute and drill bit tip.
Rough Sharpening Flute
(a) Sharpening Down (b) Sharpening Up
