When people talk about drill bit performance, they usually focus on the cutting edges or the tip angle. But there is one small feature at the very center of the drill bit that plays a surprisingly important role - the chisel edge.
Although it doesn't actually "cut" material in the traditional sense, the chisel edge has a major impact on drilling efficiency, accuracy, and tool life.
Let's break it down through the most common questions.
What Is the Chisel Edge on a Drill Bit?
The chisel edge is the short line at the center of the drill tip, where the two cutting lips meet.
Unlike the cutting edges:
it does not shear material
it mainly pushes and displaces material
Because of this, the chisel edge is often considered the least efficient part of the drill bit.
Why Doesn't the Chisel Edge Actually Cut?
Cutting requires a certain cutting speed, which depends on rotation.
At the center of the drill bit:
rotational speed is nearly zero
there is no effective cutting motion
As a result, the chisel edge:
cannot form chips like the outer cutting edges
instead extrudes or compresses material
This is why drilling always requires axial force (feed pressure) to push the chisel edge into the material.
Why Is the Chisel Edge Important?
Even though it doesn't cut, the chisel edge plays several key roles:
initiates penetration into the material
helps guide the drill bit at the start of drilling
supports the overall geometry of the tip
However, it also introduces resistance, which affects drilling performance.
What Problems Does the Chisel Edge Cause?
Because the chisel edge pushes rather than cuts, it creates:
High Thrust Force
More force is required to push the drill into the material.
Increased Heat
Friction and deformation generate heat at the center.
Reduced Efficiency
Energy is wasted in deformation instead of cutting.
This is why poor chisel edge design can lead to:
slower drilling
higher wear
reduced accuracy
What Is Web Thickness and How Is It Related?
The chisel edge length is directly related to the drill bit's web thickness.
A thicker web → longer chisel edge
A thinner web → shorter chisel edge
A longer chisel edge:
increases thrust force
reduces drilling efficiency
This is why many high-performance drill bits use web thinning techniques to shorten the chisel edge.
What Is a Split Point Drill Bit?
A split point drill bit is designed to reduce the negative effects of the chisel edge.
Instead of having a single central chisel edge:
the tip is modified to create additional cutting edges
the chisel edge is effectively "split" into smaller sections
This results in:
lower thrust force
better self-centering
improved accuracy
Split point designs are especially useful in metal drilling.
Why Do Some Drill Bits Require a Pilot Hole?
The chisel edge is one of the main reasons.
Since it cannot cut efficiently:
it struggles to start a hole cleanly
it may cause the drill bit to wander
Drilling a pilot hole removes the material at the center, allowing:
the cutting edges to engage immediately
smoother and more accurate drilling
Does the Chisel Edge Matter More in Metal or Concrete?
In Metal Drilling
The chisel edge has a significant impact because:
cutting precision matters
chip formation is critical
thrust force affects tool life
In Concrete Drilling
The impact is less pronounced because:
hammer action breaks the material
cutting is less dependent on edge geometry
However, it still influences initial penetration and stability.
How Do Manufacturers Improve Chisel Edge Performance?
High-quality drill bits often include:
web thinning to shorten the chisel edge
split point geometry to improve cutting action
optimized grinding to reduce friction
These improvements make drilling:
faster
more accurate
less demanding on the operator
Final Answer: What Does the Chisel Edge Do?
The chisel edge is the central part of a drill bit that pushes material aside rather than cutting it.
While it is necessary for structural reasons, it also:
increases drilling resistance
generates heat
affects accuracy
That's why modern drill bit design focuses on minimizing its negative effects through improved geometry.
Looking for drill bits with optimized tip geometry for better performance?
At Ceres Tools, we design drill bits with advanced point geometry, including split point designs and precision grinding, to improve drilling efficiency and accuracy.
Contact us to learn more about our high-performance drilling solutions and OEM capabilities.