Tag Archives: Twist Drill

Drill bit geometry has several characteristics buy drill bit grinder

Why are twist drill bit especially easy to wear?

There are several disadvantages to the twist drill:

(1) the internal and external difference of the front Angle values of the points on the main Cutting Edge of standard twist drill is too large. The front Angle of the main cutting edge at the outer edge of the bit is about +30; The front Angle near the core is about -30.

Close to the front Angle of the drill center is too small, causing the chip to deform large, the cutting resistance is large; Near the outer edge of the anterior horn is too large, in processing hard materials, the strength of the cutting edge is often insufficient.

(2) the transverse edge is long, and the front Angle of the transverse edge is a large negative value, which is -5 4°～-6 0°, which will produce a large axial force.

(3) compared with other types of cutting tools, the main cutting edge of standard twist drill is very long, which is not good for cutting and cutting.

(4) take place after the deputy vice cutting edge of blade Angle is zero value, cause vice knife after the friction between the surface and hole wall, cutting temperature rise, the outer edge of the corner of bit wear is bigger, has processing surface roughness.Continue reading→

Introduce the angles of twist drill

The Angle of the twist drill buy twist drill bit grinder from us

The Angle of the twist drill buy twist drill bit grinder from us

The Angle of the twist drill buy twist drill bit grinder from us

α Alpha —- Lip Relief Angle

β Beta —- Wedge Angle

γ Gamma —- Land Angle

σ Sigma —- Point Angle

ψ Psi —- Chisel Edge Angle

 

The best chisel edge angle between 52 ° – 58 °

The above angle depends on the processing material.

α+β+γ=90 °

Cutter Sharpening and Re-Grinding of Twist drill

The dimension precision and surface roughness of drilling, and drilling efficiency are directly related to the quality of cutter sharpening and re-grinding of twist drill.

In short, to avoid the cases as figure (b), (c), (d) during twist drill grinding that not only improve the drilling quality, but also will improve the drilling conditions, and come to prolong the service life of the twist drill.

Figure1: The impact of bit grinding on machining

(a) Grinding Correctly
(b) Point angle asymmetry
(c) Different Length of Cutter Grinding
(d) Point angle and Cutter Grinding are asymmetric

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Cutting performances and Advantages of Ni Zhifu Ordinary Twist Drill Bit

Definition of Ni Zhifu Ordinary Twist Drill Bit: Based on standard twist drill that the cutting part is grinded onto a special shaped drill bit. The standard twist drill consist of two major cutting lips (major cutting edges) and a chisel edge. The most fatal weakness is that the negative front angle of chisel edge and dead center are larger, led to the cutting conditions are unfavorable. Ni Zhifu Ordinary Twist Drill Bit is that grinding two symmetrical crescent grooves based on standard twist drill, forming arc blade, and then sharpening two inner straight edges on the chisel edge and dead center. After that, with the chisel edge and original two straight edges, making the standard twist drill into “Three knife-points and seven knife-edges” that is the Ni Zhifu Ordinary Twist Drill Bit.Continue reading→

How to ream or countersink holes by twist drill bits?

In actual work, we will encounter some special machining phenomenon, such as machining a larger diameter hole, or bottom of hole should beflat. Today, here we introduce reaming and countersinking, let’s go.

Countersink Holes usually involves countersinking flat-bottomed hole and countersinking tapered counter bore.

Countersink Holes usually involves countersinking flat-bottomed hole and countersinking tapered counter bore.

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