The influence of drill bit geometry on drilling

As the most commonly used cutting tool in the machining process, the drill bit's geometry directly affects the drilling efficiency, hole diameter accuracy, surface roughness, and the durability and life of the drill bit. In the drill bit geometry design, the top angle, helix angle, core thickness, chisel edge shape, edge modification, and surface coating are key parameters.

Drill head angle

The apex angle is the angle of the tip of the drill bit, usually between 118° and 140°. It determines the cutting load distribution of the drill bit and the shape of the drilling entrance.

Smaller apex angle (118°): suitable for soft materials (such as aluminum, copper, plastic, etc.), with low cutting resistance and low cutting heat; Disadvantages: It is easy to damage the cutting edge during the processing of hard materials (such as steel and stainless steel), reducing the life of the drill bit.

Larger apex angle (above 135°): suitable for hard materials, the drill bit is more stable during processing, and the wear is more uniform; the cutting resistance increases, and the torque requirements for the machine tool are higher.

Helix angle

Large helix angle (35°-40°): Smooth chip removal, rapid removal of cutting heat, suitable for processing high plastic materials (such as aluminum, copper, etc.); reduced tool rigidity, which may cause vibration and chipping in hard material processing.

Small helix angle (20°-25°): Higher tool rigidity, suitable for processing hard materials (such as steel, stainless steel, etc.); poor chip removal performance, which may cause chip blockage and scratches on the processing surface.

Drill core thickness

Core thickness is the cross-sectional thickness of the center of the drill bit, usually accounting for 20%-40% of the drill bit diameter. Core thickness affects drill bit strength and cutting performance.

Thicker core (more than 40%): Improves drill bit bending strength, extends life, suitable for deep drilling and hard material processing; large cutting resistance, requires higher thrust and torque during processing.

Thinner core (about 20%): Small cutting resistance, high drill bit sharpness, suitable for efficient processing of soft materials; low bending strength, easy to deform or break.

Chisel edge shape

Traditional straight chisel edge: The cutting resistance is large and a higher thrust is required to start drilling.

Improved curved chisel edge: By grinding the chisel edge into a curved or beveled shape, the cutting resistance can be greatly reduced and the stability of the drilling entrance can be improved.

Drill bit surface coating

TiN coating: increases surface hardness, reduces friction, suitable for ordinary steel.

TiAlN coating: excellent heat resistance, suitable for high-speed cutting and hard materials.

DLC coating: has extremely low friction coefficient and is suitable for non-metallic material processing.

Processing plan

Reasonable design and optimization of drill geometry is the key to improving drilling performance. By scientifically selecting the top angle, helix angle, core thickness and coating type, combined with modern CNC technology, you can achieve higher drilling accuracy and longer tool life while ensuring processing efficiency. If your processing plan requires analysis of a certain hole position, we at Smartlathe will provide you with appropriate processing analysis to improve your processing efficiency.