Drill bits

Drill bits

The drill performs one of the most important manufacturing operations, its function is based on the production of holes in addition to punching it performs various machining processes.

What is the function of the drill bits?

Drill bits have the ability to produce deep holes, have a high length per diameter, should be used with care to improve precision and avoid wear, the efficiency of cutting fluids can cause rapid bit wear.

Why does the tip of the bit wear out?

How does the bit tip wear out?

According to the geometry of the bit the tip of the bit has a significant performance especially in the region of the cutting edge or beveled edge, most of the thrust force depends on the cutting edge, depending on the size of the relief angle of the lip for example if it is small increases the thrust force, on the contrary it can cause a chipping or breaking of the cutting edge, it requires grinding techniques to improve the cutting edge.

Why don't i know easily remove the bit?

The diameter of production of the hole is larger than the diameter of the drill, the drill is removed more easily, depending on the thermal properties of the material metallic and non-metallic materials expand which makes the diameter smaller the drill.

How to improve the surface finish of the hole?

Surface finish can be improved by subjecting the workpiece to subsequent operations such as baking and reaming

What are the speeds of the drill bit?

Suppose a drill of diameter D its cross-sectional area is:

Bit speed (MRR) depends on the speed of the rotation speed (N) and the distance of the drill that penetrates for each revolution (f).

It also depends on the type of material being used.

What are the types of drill bits?

Twist drill: this is the most common, it has a helical tip, below

What are the characteristics of the twist drill?

Angle from 118 to 135

Angle of relief from 7 to 15

Edge angle or beveled edge 125 to 135

Helix angle 15 to 30

Drill bits Staggered: its main characteristic has to do with the cone shape, which allows different diameters to be made in the holes.

Countersink and Flare Bits: make deep depressions in surfaces to accommodate bolt or screw head.

Center Drills: is used to create small holes so that the tailstock or lathe counterpoint and the centers of the head can be mounted.

Spade or paddle bits: It has removable tips or barriers, which helps to create deep holes with large diameters, has the advantage of greater rigidity, lower cost and rectify the edges.

Straight flute drills: Similar to paddle drills, they have the same function.

What is cutting fluid for?

The cutting fluid serves to cool and lubricate the bit to improve the surface of the hole and the edge of the hole.

What are the channels of the drill used for?

The loops run the length of the drill, which allow to guide the chips in a vertical direction and to transfer the cutting fluid at the tip of the drill, some drills have the ability to cut long chips, it allows to help automated machinery, the operator will not have to remove the chip in operation.

Why is the drill bit shaped like a cone?

Depending on its geometry, the angle of the tip and the diameter of the bit varies the speed of the cutting edge, helps minimize drilling forces and produces precise holes, in addition to optimizing the durability of the same.

Why does the bit break?

It can be for the following causes the bit is blunt, feed too high, the bit sticking with the hole due to the jamming of the chips in the channels, relief angle too small.

Why is my bit wearing out excessively or quickly?

The cutting speed is too high or does not contain much cutting fluid, the angle of attack may be too high, the bit is burned or there is no resistance when sharpening.

Why is the hole not perpendicular to the surface or is the hole not straight cylindrical?

Because the bit is misaligned or bent, the angles of the hawks are uneven, the core is off-center.

Why is the hole not having a correct surface finish or is the hole oversized?

The machine spindle is loose, the cutter edge is off-center, it also has to see the lateral force of the workpiece, blunt bit, it has no fluid, the bit is not properly ground and finally the bit is not aligned correctly.