How to Choose the Best Drill Bit for Stainless Steel: Drill Bit Testing Results
Which drill bit is truly the best for drilling stainless steel? The answer depends on cutting edge geometry, coating type, cooling method, and real wear during operation. Testing of 11 drill bits when drilling into steel 1.4301 clearly showed that the correct tool design has a decisive impact on hole accuracy and tool life.
⚙️ Why Is Drilling Stainless Steel Technologically Challenging?
Drilling austenitic stainless steel (1.4301 / X5CrNi18-10) is considered one of the most demanding machining operations.
Main problems when drilling stainless steel:
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high temperatures at the outer corner of the drill bit
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zero cutting speed at the drill point center
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built-up edge formation
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rapid flank and point wear
⚠️ An incorrectly selected drill bit causes inaccurate holes, higher feed forces, and significantly shorter tool life.
Professional drill bits specifically designed for stainless steel can be found at:
https://eshop.nastrojecz.cz/
How Was the Drill Bit Testing Conducted?
The testing was based on a methodology for evaluating the performance properties of axial cutting tools.
Tested variants:
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uncoated drill bits (N)
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drill bits with TripleCoating Cr coating (M)
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drill bits with TripleCoating Si coating (B)
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selected tools with cooling groove grinding (CHL)
Test conditions:
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material: austenitic stainless steel 1.4301
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drill diameter: 13 mm
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depth: 5×D
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cutting speed: 32 m/min
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feed: 0.2 mm/rev
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emulsion cooling 11%, pressure 12 bar
Each drill bit drilled 42 holes, after which the key parameters were evaluated.
What Determined the Test Winner?
1️⃣ Hole Accuracy and Geometry
The following were evaluated:
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hole center position
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diameter accuracy
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cylindricity
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perpendicularity
Statistical analysis confirmed that process stability is just as important as accuracy itself.
2️⃣ Feed Force and Torque
The average feed force was monitored for the 1st and the 42nd hole.
Lower and stable feed force means:
✔ lower tool load
✔ better cutting conditions
✔ longer tool life
3️⃣ Drill Bit Wear
The following parameters were measured:
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point wear
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flank wear
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outer corner wear
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susceptibility to built-up edge formation
The final ranking was determined using a point-based evaluation system — the lower the score, the better the performance.
Result: What Performed Best?
The best performance was achieved by an uncoated drill bit with ground cooling grooves (25N_CHL).
Key findings:
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Distribution of coolant directly into the cutting zone has a crucial effect.
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Coatings significantly influence performance.
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Drill geometry may be more important than the coating itself.
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Process stability is essential for accurate holes.
Specialized drill bits for stainless steel can be found here:
https://eshop.nastrojecz.cz/
Frequently Asked Questions
What drill bit is best for stainless steel?
The best drill bit for stainless steel has optimized cutting edge geometry, an appropriate coating for austenitic steel, and efficient cooling design. Tests have shown that cooling groove construction can significantly increase tool life.
Why does a drill bit wear quickly in stainless steel?
Due to high temperatures at the outer corner, material hardening at the cutting center, and built-up edge formation. The drill point and outer corner are the most heavily loaded areas.
Does coating matter when drilling stainless steel?
Yes.
A proper PVD coating increases thermal resistance and process stability. However, the results show that coating alone is not sufficient without proper geometry.
Is coating or cooling more important?
The experiment showed that efficient coolant distribution can have the same or even greater impact than the coating itself. The ideal solution is a combination of both.
Practical Summary
When drilling stainless steel, no single parameter determines success. The key is the combination of:
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correct drill geometry
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appropriate coating
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efficient cooling
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stable cutting conditions
If you want to achieve precise holes and long tool life, choose drill bits specifically designed for stainless steel at:
https://eshop.nastrojecz.cz/
More articles:
-
Drill Bit Tests with New Geometry
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CZ005 Drill Bit – A New Member of the Product Family
