How to Improve the Service Life of Multicone Drill Bits?

Multicone drill bits are widely used in metalworking, industrial manufacturing, sheet metal fabrication, and precision drilling applications. Their multi-step or multi-conical cutting geometry allows users to create holes of different diameters with a single tool, improving drilling efficiency and reducing tool changes.

However, like other cutting tools, multicone drill bits are subject to wear, overheating, chipping, and cutting-edge damage during operation. Improper drilling parameters, unsuitable materials, poor lubrication, and incorrect handling can significantly shorten their service life.

Extending the service life of multicone drill bits is not only about reducing tool replacement costs. It also helps maintain consistent hole quality, improve production efficiency, and reduce manufacturing downtime.

So, how can you make multicone drill bits last longer? Below are practical techniques for improving their durability and cutting performance.

1. Choose the Right Multicone Drill Bit Material

Material selection is one of the most important factors affecting drill bit service life. Different multicone drill bit materials offer different levels of hardness, toughness, heat resistance, and wear resistance.

Common materials include:

High-Speed Steel (HSS)

HSS multicone drill bits are widely used for general-purpose drilling. They offer good toughness and can withstand moderate cutting temperatures. They are suitable for drilling softer metals, aluminum, mild steel, and various sheet metal materials.

Cobalt High-Speed Steel (HSS-Co)

Cobalt alloy drill bits provide improved heat resistance and hardness compared with standard HSS tools. They are particularly useful for drilling stainless steel and other tougher metals.

Carbide

Carbide multicone drill bits offer excellent hardness and wear resistance. They are suitable for demanding industrial applications where high cutting performance and long tool life are required. However, carbide is more brittle than HSS and requires proper machine stability and operating conditions.

Choosing the appropriate material for the workpiece helps prevent premature wear and cutting-edge damage.

2. Use the Correct Drilling Speed (RPM)

Operating speed has a direct influence on the service life of multicone drill bits.

If the rotational speed is too high, excessive friction and heat can develop at the cutting edges. This may cause discoloration, loss of hardness, premature wear, or even cutting-edge failure.

If the speed is too low, drilling efficiency may decrease, and excessive pressure may be required to maintain cutting performance.

To achieve better results:

• Follow the manufacturer’s recommended cutting speed.
• Adjust RPM according to the drill bit diameter and workpiece material.
• Use lower cutting speeds for tougher materials such as stainless steel.
• Avoid excessive rotational speeds when drilling thick metal.
• Monitor temperature and cutting conditions during operation.

Remember that cutting speed and RPM are not the same. The appropriate RPM depends on the cutting diameter.

The relationship can be calculated using:

RPM = (Cutting Speed × 1000) / (π × Drill Diameter)

Where:

• RPM = Rotational speed in revolutions per minute.
• Cutting Speed = Recommended cutting speed in meters per minute.
• Drill Diameter = Effective cutting diameter in millimeters.
• π = Approximately 3.1416.

For multicone drill bits, use the effective cutting diameter of the step currently engaging the workpiece when calculating the operating speed.

3. Apply Suitable Cutting Lubrication

Lubrication plays an essential role in reducing friction and controlling heat during drilling.

Without sufficient lubrication, the cutting edges may experience excessive temperatures, accelerating tool wear and reducing cutting performance.

Proper lubrication offers several benefits:

• Reduces friction between the drill bit and workpiece.
• Helps control cutting temperatures.
• Reduces built-up edge formation.
• Improves chip evacuation.
• Minimizes cutting-edge wear.
• Produces smoother hole surfaces.

When drilling stainless steel or other difficult-to-machine metals, an appropriate metalworking cutting fluid is particularly important.

For aluminum, use a lubricant suitable for aluminum machining to reduce material adhesion and prevent chips from sticking to the cutting edges.

Always select cutting fluids according to the drill bit material, workpiece material, and manufacturer’s recommendations.

4. Avoid Excessive Feed Pressure

Applying excessive pressure is a common cause of premature multicone drill bit failure.

Although sufficient feed pressure is necessary for effective cutting, too much force can overload the cutting edges, especially when drilling harder materials.

Excessive pressure may lead to:

• Cutting-edge chipping.
• Drill bit deformation.
• Increased friction and heat.
• Poor hole accuracy.
• Premature tool failure.

Use a consistent and controlled feed rate. Allow the cutting edges to remove material efficiently instead of forcing the drill bit through the workpiece.

If the drill bit requires unusually high pressure to cut, check whether the cutting edges are worn, the operating speed is incorrect, or the selected tool is unsuitable for the material.

5. Keep the Workpiece Securely Clamped

Workpiece stability is another important factor in extending multicone drill bit service life.

If the material moves or vibrates during drilling, the drill bit may experience uneven cutting forces. This can damage individual cutting edges and reduce drilling accuracy.

To prevent this problem:

• Secure the workpiece using suitable clamps or fixtures.
• Ensure the workpiece is properly supported.
• Avoid drilling loose or unstable sheet metal.
• Check that the machine table and spindle are stable.
• Minimize vibration during operation.

Thin sheet metal requires particular attention because it can flex or vibrate under drilling pressure.

A stable setup helps distribute cutting forces more evenly and reduces unnecessary stress on the drill bit.

6. Remove Metal Chips Regularly

Metal chips can accumulate around the cutting edges and interfere with the drilling process.

When chips are not removed properly, they may become trapped between the drill bit and workpiece, increasing friction and heat.

This can result in poor surface finishes, damaged cutting edges, and reduced tool life.

Good chip management practices include:

• Use suitable chip evacuation methods.
• Remove accumulated chips when necessary.
• Avoid allowing long chips to wrap around the drill bit.
• Use compressed air or appropriate cleaning methods when the machine is safely stopped.
• Ensure that the cutting geometry allows chips to escape effectively.

Never attempt to remove tangled chips by hand while the machine is running.

7. Select the Correct Drill Bit Diameter and Step Configuration

Using the correct multicone drill bit size is essential for maintaining cutting efficiency.

Multicone drill bits are designed with multiple cutting diameters or conical steps. Each step serves a specific drilling requirement.

Using an unsuitable diameter or step configuration can increase cutting resistance and place unnecessary stress on the tool.

Before drilling, consider:

• The required hole diameter.
• The thickness of the workpiece.
• The number of cutting steps.
• The workpiece material.
• The required hole tolerance.
• The available machine power.

Choose a multicone drill bit that matches the actual drilling application rather than using an oversized or unsuitable tool.

8. Avoid Sudden Impact and Side Loading

Multicone drill bits are designed primarily for axial drilling forces. Applying excessive lateral force can damage their cutting geometry.

Side loading may cause uneven wear, cutting-edge breakage, and poor hole accuracy.

To protect the tool:

• Keep the drill bit aligned with the drilling axis.
• Avoid moving the drill sideways while cutting.
• Do not use the drill bit as a lever.
• Avoid sudden impacts against the workpiece.
• Use appropriate machine fixtures for angled drilling applications.

Carbide multicone drill bits require particular care because their high hardness is accompanied by lower impact toughness.

9. Inspect and Maintain Drill Bits Regularly

Regular inspection helps identify early signs of wear before they develop into serious problems.

A multicone drill bit should be checked for:

• Worn or rounded cutting edges.
• Chipped cutting tips.
• Cracks or visible damage.
• Excessive discoloration caused by overheating.
• Uneven wear between cutting steps.
• Built-up metal deposits.
• Damaged shanks or mounting surfaces.

If cutting performance decreases, investigate the cause rather than continuing to operate the tool under excessive pressure.

Some drill bits can be professionally resharpened, depending on their material, geometry, coating, and manufacturer’s recommendations. However, multicone drill bits require accurate restoration of their original cutting geometry to maintain proper performance.

10. Clean and Store Multicone Drill Bits Properly

Correct storage prevents unnecessary damage when drill bits are not in use.

Metal chips, moisture, and improper handling can contribute to corrosion and cutting-edge damage.

Follow these storage practices:

1. Clean the drill bit after each use.
2. Remove metal chips and cutting-fluid residue.
3. Dry the tool thoroughly.
4. Apply a suitable rust-preventive treatment when necessary.
5. Store drill bits in protective cases or organized tool holders.
6. Keep cutting edges separated to prevent accidental contact.
7. Store tools in a clean, dry environment.

Avoid placing multicone drill bits loosely in drawers or containers where they may collide with other metal tools.

11. Use the Right Machine and Tool Holder

Even a high-quality multicone drill bit can wear prematurely when used with unsuitable equipment.

Machine stability, spindle accuracy, chuck condition, and tool-holding strength all influence drilling performance.

For longer service life:

• Use a machine with sufficient power and rigidity.
• Check spindle runout regularly.
• Ensure the drill bit is securely mounted.
• Use a suitable chuck or tool holder.
• Avoid excessive machine vibration.
• Follow the recommended operating conditions.

Excessive runout can cause uneven cutting forces, resulting in premature wear on one side of the drill bit.

12. Avoid Using Worn Drill Bits for Difficult Materials

Continuing to use a heavily worn multicone drill bit can create additional problems.

A dull cutting edge requires more force to penetrate the workpiece. This increases heat generation and places additional stress on the drill bit and machine.

It may also produce oversized holes, rough edges, and inconsistent dimensions.

Replace or professionally recondition the drill bit when its cutting performance is no longer acceptable.

Using a sharp and properly maintained tool is generally more economical than continuing to operate a damaged one.

Common Factors That Shorten Multicone Drill Bit Service Life

The following table summarizes common problems and their recommended solutions.

How Long Should a Multicone Drill Bit Last?

There is no universal service-life figure for multicone drill bits. Their actual lifespan depends on several operating conditions.

Important factors include:

1. Drill Bit Material: Carbide and cobalt HSS generally offer better wear and heat resistance than standard HSS in their appropriate applications.

2. Workpiece Material: Aluminum and mild steel typically impose different cutting demands from stainless steel and other hard alloys.

3. Cutting Parameters: Excessive RPM, feed pressure, and cutting temperatures can accelerate wear.

4. Lubrication: Proper cutting fluid can reduce friction and heat generation.

5. Machine Conditions: Poor alignment, spindle runout, and vibration can significantly shorten tool life.

6. Maintenance: Regular cleaning, inspection, and appropriate storage help preserve cutting performance.

For industrial applications, monitoring the number of holes drilled, cutting performance, and tool condition provides a more reliable way to determine when a drill bit should be replaced.

Conclusion: How to Maximize the Service Life of Multicone Drill Bits

Improving the service life of multicone drill bits requires the right combination of tool selection, operating parameters, lubrication, machine stability, and regular maintenance.

The most effective practices include:

• Choose the correct HSS, cobalt, or carbide material.
• Maintain the recommended cutting speed and feed rate.
• Use suitable cutting lubrication.
• Avoid excessive drilling pressure.
• Secure the workpiece properly.
• Maintain effective chip evacuation.
• Prevent vibration and side loading.
• Inspect cutting edges regularly.
• Clean and store drill bits correctly.

By following these practices, manufacturers and professional users can reduce premature tool wear, improve drilling consistency, and achieve better long-term production efficiency.

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