Jusheng

Think of two scenarios the following: When CNC machining aluminum alloy parts, standard drill bits quickly wear down, creating substandard hole diameters. Or, when the wrong drill bit is used, and this results in low efficiency and high cost when CNC machining stainless steel parts. The root cause of these issues is the question, 'Which drill bit is stronger?'

In addressing this question, in this guide first we will dispel the mystique of reliability and eliminate the myth that 'hardness is everything'. We then numerically compare hardness of drill bit materials, compare popular varieties, describe the JS testing procedure, and provide cost-effectiveness choice alternatives, and finally use case studies to verify and help you choose the right drill bit.

Core Answer Summary

Drill Bit Types	Core Material and Coating Technology	Ultimate Hardness and Materials that Can be Used	Cost-Effectiveness and Suggested Applications
High-Speed ​​Steel (HSS)	High-carbon alloy steel	HV 600-800, low-carbon steel, aluminum alloys.	High, recommended for home DIY and processing of simple parts.
Cobalt High-Speed ​​Steel (HSS-Co)	High-speed steel with 5%-8% cobalt content	HV 800-1000, gold, stainless steel.	Medium, recommended for small-batch industrial processing of parts.
Carbide	Tungsten carbide alloy-based	HV 1800-2200, hard steel, titanium alloys.	Medium-high, recommended for mass and high-precision production.
Titanium Nitride Coating (TiN)	Substrate + TiN Coating	HV 3000+, medium-to-high hardness materials.	Medium, recommended for improving drill wear resistance.
Diamond/PCD	Polycrystalline diamond drill tips	HV 8000-10000, composite and non-ferrous metals.	Low, recommended for high-precision, high-volume machining of non-ferrous metals.

This article will answer for you:

What are the distinctions between hardness of drill bits with different materials? What application is appropriate for the different mainstream models of drill? How do we scientifically test the best drill bits? And how do we choose the most cost-saving drill bit based on machining requirement, accuracy, and amount?

Why Trust This Guide?JS Tool Testing Insights

Have you ever been overwhelmed by the thousands of recommendations when selecting a drill bit? Worry not, the authority of this guide is founded on JS Precision Manufacturing's decades of experience in tool testing, not just words.

For several decades, JS has been deeply involved in the business of machining, not only manufacturing an extensive range of high-precision parts for customers, ranging from common aluminum alloys to hard-to-machine titanium alloys, but also investing tremendous effort in conducting thousands of tests on various types of drills under extensive ranges of machining conditions.

We diligently track every test data, earnestly collect customers' comments on drill use issues, and regularly revise our testing parameters to fully understand the performance of every drill bit.

All conclusions in this manual are based on real test data and customer case studies. When you do not know what drill to choose, ponder these tested-and-proven experiences.

With years of experience in test tools, JS Precision Manufacturing is able to guarantee your custom CNC machining manufacturing. Once you place an order, we are able to increase production quickly and deliver high-quality products at an affordable CNC machining price.

Hardness Is Not The Only Dimension: Defining 'Strongest' In Several Dimensions

Judging the strength of a drill bit cannot be based solely on its hardness. 'Strongest' needs to be defined from multiple dimensions, as different machining requirements have different focuses.

Hardness: Foundation for Machining of High-hardness Materials

Hardness, in terms of Rockwell hardness (HRC) or Vickers hardness (HV), is the foundation for machining of high-hardness materials. Drilling of mold steels of HRC 50 and above necessitates a drill of high hardness, otherwise the cutting edge is chipped. Conversely, when machining low-hardness aluminum alloys, a too highly hardened drill will crack because of brittleness.

Toughness: Resistance to shock and vibration

When drilling deep holes or irregular CNC machining parts, drill bits experience vibration and impact. Drill bits having high toughness are less likely to fracture. For example, in the machining of components that include notches, solid carbide drill bits can fracture while cobalt high-speed steel drill bits resist impact.

Heat Resistance: Protection against long-term machining

High-speed drilling creates much heat, and drill bits with low heat resistance tend to soften and wear out. To machine stainless steel in lots, high-speed steel drill bits are replaced every half hour, while coated carbide drill bits can machine for hours.

Wear Resistance: The Main Indicator of Drill Working Life

Wear resistance affects drill working life. Increased wear resistance allows more parts to be machined at reduced costs. Machining specialty CNC machining large quantities of parts, PCD-tipped drill bits possess service life dozens of times as much as general high-speed steel drills.

Efficiency of Cutting: A Key Indicator Influencing Machining Cost

Drilling speed and evacuation of chips are regulated by cutting efficiency. By offering online CNC machining services, high-efficiency drill bits can save machining time, improve productivity, and lower customers' CNC machining price.

After understanding the multi-dimensional performance of drill bits, choosing JS Precision Manufacturing can bring you peace of mind. We know every use of drill bits, simplify ordering, and are able to help you optimize your CNC machining price.

Hardness King: Hardness Gradient Rankings Of Drill Bits From Various Materials

The following is a compilation of hardness gradients of drill bits of various materials, as per test data and industry specification.

Absolute Champion: Polycrystalline Diamond (PCD) Drill Tips

PCD drill tips are 8,000-10,000 HV Vickers hardness and are applied on non-ferrous and non-metallic materials such as copper and aluminum alloys.

When machining precision parts of aluminum alloys, they can achieve surface roughness of Ra 0.2μm or less. They are, however, expensive ($200-500 per drill tip) and cannot process carbon-containing materials such as steel.

Runner-Up: Solid Carbide

Solid carbide drills are Vickers hardness 1800-2200 HV and may be utilized to machine various high-hardness material such as stainless steel and mold steel.

They possess high precision and fine abrasion resistance when machining stainless steel CNC machining parts. They lack good toughness and are prone to breakage upon collision. Their price is $50-150 USD and offer greater cost-performance than PCD drill tips and are very extensively used.

Third Place: Cobalt High-Speed Steel (HSS-Co) & Surface Coating Drills

Cobalt HSS-Co drills have a hardness of 800-1000 HV and contain cobalt. Cobalt HSS-Co drills are suitable for machining medium- and low-hardness alloy steels and stainless steels, with economical cutting of small quantities of CNC machining parts, at a cost of $10-30 USD per drill.

Advanced coating drills are HSS-Co or carbide drills coated with TiN, TiCN, or other coatings. TiAlN coatings achieve hardness levels of more than 3000 HV, extending drill life by 2-5 times. The price is 20%-50% higher, at $15-45 per drill.

Fourth Position: High-Speed Steel (HSS)

HSS drill bits have a Vickers hardness of 600-800 HV, good toughness, and a low price ($5-15 per drill). They are suitable for low-hardness materials such as mild steel and aluminum alloys and are commonly used for home DIY or simple CNC machining. However, they have poor heat and wear resistance, and wear quickly when machining high-hardness materials or in batches.

Bottom: Black Oxide/Titanium-Coated HSS

Their hardness is 650-850 HV. Black oxide coating is resistant to rust, and the titanium coating slightly improves wear resistance, but the effect is negligible. Their cost is $8-20. They are suitable for low-demand machining, but are unsuitable for machining high-hardness materials or for batch machining.

JS provides a wide range of applications for drill bits, with reliable quality custom CNC machining parts, fast turnaround, and reasonable prices for CNC machining.

Family Showdown: One-Stop Comparison Of The Five Main Drill Bit Types

There are several types of drill bits with different performance properties and application conditions. The following is a comparison of the five major types.

Drill Type	Suitable Materials	Merits	Demerits	Suggested Processing
Twist Drill	Cast iron, mild steel, aluminum alloy, plastic.	Extremely versatile and economical.	Lower accuracy, rapid wear when cutting high-hardness material, and poor chip elimination.	Suitable for home use and general CNC machining.
Center Drill	Alloy steel, stainless steel, mild steel.	Accurate positioning and prevents drill drift.	Drills center holes only, limited use.	Suitable for positioning before precision CNC machining.
Step Drill	Copper alloy, aluminum alloy, thin steel.	Drill multiple diameters of holes simultaneously, high efficiency, and good chip removal.	Will not be able to machine thick material, will quickly wear on machining hard materials, and costly.	Best suited for thin-walled custom CNC machining parts.
Deep Hole Drill	Cast steel, stainless steel, and titanium alloy.	Can drill deep holes (depth-to-diameter ratio > 10:1), good chip evacuation, high accuracy.	Low cutting speed, special equipment needed, and expensive.	Can be employed for deep-hole CNC machining parts.
PCD Drill	Aluminum alloy, copper alloy, composite material, plastic.	High hardness, good wear resistance, long life, high precision, and low surface roughness.	Cannot be used to machine steel, expensive, and brittle.	Special CNC machining high-precision manufacturing parts.

Brutal Testing: How JS Scientifically Selects The Ideal Drill Bit

JS trusts scientific testing to choose the perfect drill bit. The steps are as follows.

Test Sample Preparation

Ten drills of eight common drill types (for example, general HSS twist drills and HSS-Co twist drills) were selected as test workpieces commonly used in custom CNC machining manufacturing, e.g., mild steel, stainless steel, aluminum alloy, and titanium alloy.

Experimental Equipment and Parameter Settings

A HAAS VF-2 high-precision CNC machining center was used, and values set according to the drill bit and work material. For example, in drilling 304 stainless steel, speed was 800 rpm, feed rate was 0.1 mm/min, and hole depth was 20 mm, for drilling 6061 aluminum alloy, speed was 2000 rpm, feed rate was 0.2 mm/min, and hole depth was 20 mm.

Test Items

• Service Life Test:The drill bit was operated continuously, and the number of holes drilled before wear or fracture occurred.

• Drilling Accuracy Test:After drilling 10 holes, the accuracy was inspected with a coordinate measuring machine.

• Efficiency Test:The energy and time required to machine a standard hole (10mm diameter, 20mm depth) were recorded.

• Impact Resistance Test:A simulated impact test was employed to assess fracture resistance.

Test Result Analysis and Optimal Drill Selection

Based on an overall score taking into account lifespan (30 points), accuracy (25 points), efficiency (25 points), and impact resistance (20 points), PCD drills (over 90 points) were applied for high-precision custom CNC machining manufacturing. TiAlN-coated carbide drills (around 85 points) were applied for mass production of stainless steel CNC parts. HSS-Co drills (around 75 points) were applied for impact conditions.

JS is supported by scientific testing and can match you with the optimal types of drill bits and processing solutions. Our custom CNC machining parts are assured to be of superior quality, and we will be happy to work with you.

Cost-Effectiveness: How To Make the Smartest Choice Based On Your Needs

Choose by Material

Material Hardness	Suitable Drill Bit	Applicable Scenarios	Target Price (Per Drill)
≤HRC 20	Standard HSS Drill Bit	Home DIY, Small Quantity, Simple Parts	$5-15
≤HRC 20	HSS-Co Drill Bit	Small Batch Production (≤1000 pieces per month)	$10-30
HRC 20-40	TiAlN Coated Carbide Drill Bit	Mass Production (1000-5000 pieces per month)	$15-45
HRC 20-40	Solid Carbide Drill Bit	High-Precision Machining (Hole Diameter Error ≤0.02mm)	$50-150
> HRC 40	Solid Carbide Drill Bit (Steel)	Machining Ultra-High Hardness Materials like Steel	$80-200
>HRC 40	PCD Drill (Non-Ferrous Metals)	Machining of High-Volume Non-Ferrous Metals	$200-500

Selection Based on Precision Requirements

• Low Precision (Aperture Error ≤ 0.1mm, Ra ≤ 3.2μm): Choose a common HSS or HSS-Co drill to reduce CNC machining costs.
• Medium Precision (Aperture Error ≤ 0.05mm, Ra ≤ 1.6μm): Use a TiAlN-coated carbide drill for the majority of industrial CNC machining parts.
• High Precision (Aperture Error ≤ 0.02mm, Ra ≤ 0.8μm): Use a solid carbide or PCD drill to ensure part performance.

Selection Based on Processing Volume

• Small Volume (Monthly Production ≤ 500 pieces): Use an HSS-Co or common coated HSS drill to save on initial costs.
• Medium Volume (Monthly Output 500-5000 pieces): Choose a TiAlN-coated carbide drill to compromise life and price.
• High volumes (monthly output > 5,000 units): Choose PCD drills for non-ferrous materials and high-quality solid carbide drills for steel to reduce long-term expense.

JS Precision Manufacturing can help you select low-cost drills and achieve efficient machining. Our online CNC machining services ensure prompt order processing and top CNC machining prices.

Case Study: 300 Drills In Aerospace Composites With Zero Scrap

Customer Challenge:

One drone company had no issue with cutting carbon fiber composite wings: using the world's top carbide drills, delamination and burrs were still encountered. Drills were replaced after a mean of 10 holes, too expensive in machining and only delivering a 70% yield rate, which hit mass production severely on all fronts.

JS's Solution:

The JS Precision Machining personnel analyzed and concluded that the issue resulted from abrasiveness of high carbon fiber. The hardness of the cutting and the hardness of the coating on standard drill bits were not sufficient to resist abrasion, leading to 'tearing' of the material.

We created a customized solution for the customer:

• Replace drill bit type.We employed a polycrystalline diamond (PCD) drill tip suited for composite materials, leveraging PCD's superior wear resistance in an effort to minimize carbon fiber abrasion.
• Optimize cutting parameters. Through repeated experiment and adjustment, we lowered the drilling feed rate from 0.1mm/r/min to 0.05mm/r/min and the rotating speed from 1500rpm to 2500rpm, achieving 'micron-level cutting' and eliminating material tearing.

Ultimate Outcome:

The PCD drill bit drilled over 300 holes per cycle, smooth and burr-free holes with no deburring afterwards needed, with an efficiency improvement of 40%. Although the PCD drill cost more at $350 per tool (the original one cost $80), the cost per hole after amortization reduced from $8 to $1.20, with a 100% yield rate and removal of all production bottlenecks.

FAQs

Q1. Why can't my new drill bit even cut through steel?

99% of the time, the drill bit is at the wrong angle. Steel is supposed to be drilled with 118° or 135° point angle, but most economy drill bits are honed to about 90° for light general-purpose work and therefore can't cut metal. Furthermore, cutting too aggressively without using lubricating cutting fluid over-heats the drill bit and makes it useless.

Q2. Does a drill bit actually 'drill' something?

Of course not.Glass, tile, and heat-treated steel are very hard materials and can't be drilled by regular drill bits, rather, they must be literally broken apart. Utilize diamond grinding heads or tungsten carbide milling cutters since they 'grind' rather than 'drill' these materials.

Q3. How do I prolong the life of my drill bit in the best manner?

There are three main points:

• Use the proper cutting fluid or lubricant. Threading oil, WD-40, or motor oil are superior to grinding dry.
• Use the proper rate of rotation. The tougher the material, the lower the rate of rotation.
• Use steady and proper pressure to allow the cutting edge to function effectively and avoid friction heat.

Summary

Actually, there is no 'best' drill bit, but the most appropriate. On choosing a drill bit, take into consideration the material to be machined, the precision required, and the batch size. This will enable you to use the most economical drill bit, reducing CNC machining price and maximizing machining efficiency and guaranteeing quality.

If you want assistance in selecting drill bits, just contact JS. We will provide you with professional service and guidance. Whatever drill bits you require, we can meet your needs. We offer online CNC machining services with professional follow-up in the order process and improved CNC machining rates. Machining is easier and more convenient after you make the right choice with us.