In modern machining industries such as heavy machinery, mold manufacturing, automotive components, and structural equipment, large-diameter hole machining is a common requirement. However, as the hole size increases, the machining process often becomes more challenging due to higher cutting forces, faster tool wear, and longer machining cycles.

SHANG TZANG WANG ENTERPRISE CO., LTD., established in 1987 in Taiwan, is a professional manufacturer specializing in precision cutting tools. The company develops a wide range of tools including tungsten carbide end mills (ST660, ST880, ST880X series), indexable high-speed drills, rapid core-stay drills with throw-away inserts, and large-diameter spade drills. With decades of experience, the company continuously develops new cutting solutions to improve machining efficiency and meet diverse manufacturing requirements.

Among these solutions, Rapid Core-stay Drills W/Throw-away Inserts are designed specifically to improve efficiency in large-diameter drilling applications.

This article explores the common problems encountered in large-diameter CNC drilling and explains how core-stay drilling technology can significantly improve machining efficiency.

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Common Problems in Large-Diameter CNC Drilling

When machining large-diameter holes, manufacturers often encounter several challenges that affect productivity, tool life, and machining stability.

Common problems include:

• High cutting load on the spindle
• Rapid tool wear during heavy drilling
• Long machining cycles for large holes
• Chip evacuation difficulties

These issues can reduce machining efficiency and increase manufacturing costs. Below is a closer look at each challenge.

High Cutting Load

When drilling large holes with traditional solid drills, the cutting edge must remove material from the entire cross-section of the hole. As the hole diameter increases, the amount of material removed increases significantly.

This results in:

• Higher spindle load
• Increased cutting resistance
• Greater stress on the machine and tool

In extreme cases, the spindle torque requirement may approach the machine's operational limits.

Rapid Tool Wear

Large-diameter drilling generates significant cutting heat and resistance. Under these heavy cutting conditions, traditional drills may experience rapid wear.

This can lead to:

• Frequent tool replacement
• Higher tooling costs
• Reduced machining stability

In high-volume manufacturing environments, excessive tool wear can greatly affect productivity.

Long Machining Cycles

Because solid drills remove the entire volume of material inside the hole, drilling large diameters requires more time.

This leads to:

• Longer machining cycles
• Lower production efficiency
• Higher overall manufacturing costs

Chip Evacuation Difficulties

Large holes generate a large volume of chips during drilling. If chips cannot be removed efficiently, they may accumulate inside the hole.

This may cause:

• Tool breakage
• Poor hole surface finish
• Increased cutting temperature

Efficient chip evacuation is essential to maintain stable drilling conditions.

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How Core-Stay Drills Improve Large-Diameter Drilling Efficiency

A core-stay drill is designed to remove material only from the outer circumference of the hole while leaving a solid core in the center. By reducing the amount of material removed during drilling, this design provides several key advantages compared with traditional solid drills.

Key advantages of core-stay drills include:

• Reduced cutting load
• Faster machining speed
• Longer tool life with replaceable inserts
• Improved chip evacuation and cutting stability

These benefits help manufacturers achieve higher productivity and more stable machining performance.

Below is a closer look at each advantage.

Reduced Cutting Load

Because the drill removes only the outer ring of material instead of the entire cross-section, the cutting force required during drilling is significantly lower.

This results in:

• Lower spindle load
• Reduced machine stress
• More stable cutting conditions

Machines with limited spindle power can therefore perform large-diameter drilling more efficiently.

Faster Machining Speed

Since less material is removed during drilling, core-stay drilling can significantly reduce machining time compared with traditional solid drilling.

Manufacturers benefit from:

• Shorter cycle times
• Higher production efficiency
• Increased machining throughput

This is especially valuable in high-volume manufacturing.

Longer Tool Life with Replaceable Inserts

Core-stay drills equipped with throw-away inserts allow only the cutting inserts to be replaced when worn, while the drill body can continue to be used.

This insert-based system provides:

• Lower tooling cost
• Reduced tool replacement time
• Consistent cutting performance

This helps manufacturers maintain stable machining quality while lowering overall tooling costs.

Improved Chip Evacuation and Cutting Stability

Large-diameter drilling produces a significant amount of chips. The design of core-stay drills helps guide chips away from the cutting zone more efficiently.

Better chip control helps:

• Prevent chip clogging
• Maintain stable cutting temperature
• Reduce the risk of tool breakage

This leads to smoother drilling operations and improved machining reliability.

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Solid Drill vs Core-Stay Drill Comparison

Feature	Solid Drill	Core-Stay Drill
Material Removal	Entire hole cross-section	Outer ring only
Cutting Load	High	Lower
Machining Speed	Slower	Faster
Tool Replacement	Replace entire drill	Replace inserts only
Tool Cost	Higher	Lower over time
Chip Evacuation	More difficult	More efficient

This comparison clearly shows why core-stay drills are increasingly preferred for large-diameter hole machining.

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Applications of Rapid Core-Stay Drills W/Throw-away Inserts

Rapid Core-stay Drills W/Throw-away Inserts are designed for use across various machining platforms.

They are suitable for:

• CNC lathes
• Conventional lathes
• CNC milling machines
• Boring machines
• Vertical drilling machines
• Horizontal drilling machines

This versatility allows manufacturers to perform large-diameter drilling on multiple types of machine tools while maintaining stable cutting performance.

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Conclusion

Large-diameter drilling presents several challenges in CNC machining, including high cutting load, rapid tool wear, long machining cycles, and chip evacuation problems.

Core-stay drilling technology offers an efficient solution by removing only the outer portion of the hole and leaving a solid core in the center. This reduces cutting force, shortens machining time, and improves tool life.

For manufacturers seeking higher efficiency in large-diameter drilling operations, Rapid Core-stay Drills W/Throw-away Inserts provide a reliable and productive machining solution.

If you are looking for a more efficient solution for large-diameter drilling, SHANG TZANG WANG ENTERPRISE CO., LTD. provides a range of high-performance cutting tools including rapid core-stay drills with throw-away inserts and indexable drilling solutions. With decades of manufacturing experience, we are committed to helping manufacturers improve productivity and machining stability. For more details about our drilling tools, please refer to our catalog or visit our website for further information.