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What is a drill bit? What are the different types?

What is a drill bit? What are the different types?

June 13,2023

A drill bit is a commonly used cutting tool component. It finds applications ranging from DIY home renovations to industrial production lines. Whether it's drilling holes in cement, metal, wood, tiles, or glass, drill bits are essential. Today, we will share with you what a drill bit is and the various types available. After reading this, you will be able to choose the right drilling and cutting tool for your needs more efficiently!

What is the purpose of a drill bit?

A drill bit is a cutting tool that operates by rotating to remove material and create holes. There are various sizes, shapes, and types of drill bits available. Different materials require different drill bits based on their rigidity and external design. Materials such as steel, hardened steel, stainless steel, cast iron, titanium alloy, nickel alloy, aluminum, copper, and plastics can be cut using specific drill bits. Some manufacturers also apply nanocoatings or incorporate center water outlets to enhance the cutting performance of the drill bits.

What are the types of drill bits?

Common types of drill bits include spot drills, center drills, micro-drills, high-speed drills, and flat head drills. Many people refer to twist drills as spiral drills, but in reality, any drill bit with a rotating cutting design for creating circular holes falls under this category. Here's a detailed introduction to each type：

Spot Drill

A spot drill, also known as a center drill, is a pre-drilling tool used to prevent drilling deviation. It incorporates a taper design to precisely locate the drilling position, ensuring that other functional drill bits can accurately find the center hole.

Drill Bit Category：Solid Carbide Spot Drill
Drill Bit Material：MG Carbide
Drill Bit Coating：AlTiN X-NaNo
Suitable for cutting materials: Carbon steel, low alloy steel, high alloy steel, hardened steel, cast iron.
Product Models：D921X、D922X、D932X、D923X、D924X

Spot Drill Feed Chart

Cutting Material	Carbon Steel	Low Alloy Steel (~24HRC)	Hardened Steel (~30HRC)	Hardened Steel (30~38HRC)	Hardened Steel (38~48HRC)	Cast Iron
Cutting Speed m/min	40~85vc	40~85vc	40~85vc	20~30vc	15~25vc	65~100vc
Drill Diameter（mm）	Feed Rate f(mm/r)
0.5	0.003~0.02	0.003~0.02	0.003~0.02	0.003~0.02	0.003~0.02	-
1	0.01~0.04	0.01~0.04	0.01~0.04	0.01~0.04	0.01~0.04	0.01~0.035
2	0.03~0.07	0.03~0.07	0.03~0.07	0.03~0.07	0.03~0.07	0.03~0.063
3	0.04~0.085	0.04~0.085	0.04~0.085	0.04~0.085	0.04~0.085	0.05~0.095
4	0.05~0.12	0.05~0.12	0.05~0.12	0.05~0.12	0.05~0.12	0.07~0.15
6	0.06~0.13	0.06~0.13	0.06~0.13	0.06~0.13	0.06~0.13	0.12~0.2
8	0.08~0.16	0.08~0.16	0.08~0.16	0.08~0.16	0.08~0.16	0.15~0.2
10	0.1~0.2	0.1~0.2	0.1~0.2	0.1~0.2	0.1~0.2	0.1~0.25
12	0.15~0.25	0.15~0.25	0.15~0.25	0.15~0.25	0.15~0.25	0.2~0.3
16	0.15~0.3	0.15~0.3	0.15~0.3	0.15~0.3	0.15~0.3	0.25~0.35
20	0.18~0.35	0.18~0.35	0.18~0.35	0.18~0.35	0.18~0.35	0.28~0.4

Center Drill

The center drill is commonly used to create different types of center holes, primarily 60°and 90°angles. Its main purpose is to drill a small hole that can guide subsequent drilling processes. During high-speed cutting, the spiral flutes help facilitate the easy removal of metal chips.

Drill Type：Solid Carbide Drill
Drill Material：MG Carbide
Drill Coating：Uncoated Bright
Suitable Cutting Materials：Steel, Hardened Steel, Cast Iron, Aluminum, Copper
Product Model：D908

Center Drill Feed Rate Table

Cutting Material	Carbon Steel	Hardened Steel		Cast Iron	Aluminum	Copper
Cutting Material	Carbon Steel	30~38HRC	38~48HRC	Cast Iron	Aluminum	Copper
Cutting Speed m/min	20~30vc	10vc		30~35vc	55~60vc	30vc
Drill Diameter（mm）	Feed Rate f(mm/r)
0.5	0.005	0.004	0.003	0.005	0.007~0.008		0.005
0.8	0.008	0.0064	0.0048	0.008	0.011~0.012		0.008
1	0.01	0.008	0.006	0.01	0.014~0.016		0.01
1.25	0.0125	0.01	0.0075	0.0125	0.017~0.02		0.0125
1.6	0.016	0.0128	0.0096	0.016	0.022~0.025		0.016
2	0.02	0.016	0.012	0.02	0.028~0.032		0.02
2.5	0.025	0.02	0.015	0.025	0.035~0.04		0.025
3.15	0.0315	0.0252	0.0189	0.0315	0.044~0.05		0.0315
4	0.04	0.032	0.024	0.04	0.056~0.064		0.04
5	0.05	0.04	0.03	0.05	0.07~0.08		0.05

Micro Drill Bits

Micro drill bits refer to those with a diameter smaller than 3mm. They need to possess high hardness and sharpness to ensure product durability and are suitable for both rough and fine machining. They can be used for drilling materials such as steel with a hardness below HRC30, stainless steel, cast iron, aluminum alloys, copper alloys, and more.

Bit Category：Solid Carbide Drill Bits
Bit Material：MG Carbide
Bit Coating：AlTiCrN HX
Suitable Cutting Materials：Carbon steel, alloy steel, stainless steel, cast iron, aluminum, copper.
Product Models：D420HX-3、D420HX-5、D420HX-8

Micro Drill Bits Feed Rate Table

Cutting Material	Carbon Steel		Low Alloy Steel (~24HRC)		High Alloy Steel (~30HRC)		Stainless steel		Cast Iron		Aluminum		Copper
Cutting Speed m/min	37vc		37vc		34vc		31vc		37vc		37vc		20vc
Drill Diameter（mm）	Feed Rate f(mm/r)
0.2-0.5	0.002~0.007	0.002~0.007		0.002~0.007		0.002~0.007		0.002~0.007		0.004~0.015		0.002~0.007
0.55-1	0.0008~0.02	0.0008~0.02		0.0008~0.02		0.0008~0.02		0.0008~0.02		0.016~0.03		0.007~0.01
1.05-1.5	0.02~0.03	0.02~0.03		0.02~0.03		0.02~0.03		0.02~0.03		0.03~0.05		0.01~0.02
1.55-2	0.034~0.05	0.034~0.05		0.034~0.05		0.034~0.05		0.034~0.05		0.05~0.06		0.02~0.02
2.05-2.5	0.05~0.08	0.05~0.08		0.05~0.08		0.05~0.08		0.05~0.08		0.06~0.1		0.02~0.04
2.55-3	0.08~0.09	0.08~0.09		0.08~0.09		0.08~0.09		0.08~0.09		0.10~0.12		0.04~0.05

High-Speed Drill Bits

High-speed drill bits refer to drilling tools that operate at speeds twice as fast as traditional methods. They are characterized by high hardness, wear resistance, and heat resistance. In addition to improving production speed, they also increase the amount of material removed during a fixed period of time. Another type of high-performance drill bit is the internal coolant high-speed drill bit, which utilizes a center water outlet design to reduce the cutting temperature of the drill bit and enhance chip evacuation capability.

Drill Bit Category：Solid Carbide Drill Bits
Drill Bit Material：MG Carbide
Drill Bit Coating：AlTiSiN-TX
Suitable for Cutting Materials：Carbon Steel, Low Alloy Steel, High Alloy Steel, Hardened Steel, Cast Iron
Product Models：D421TX、D422TX、D423TX-3、D423TX-5、D423TX-8、D423TX-12、D423TX-16、D423TX-20、D423TX-25、D423TX-30、D421TX、D422TX

High-Speed Drill Bits Feed Rate Table

Cutting Material	Carbon Steel	Low Alloy Steel (~24HRC)	High Alloy Steel (~30HRC)	Hardened Steel (30~38HRC)	Hardened Steel (38~48HRC)	Cast Iron
Cutting Speed m/min	60~100vc	60~100vc	60~100vc	40~65vc	30~45vc	60~100vc
Drill Diameter（mm）	Feed Rate f(mm/r)
1-2.5	0.03~0.07	0.03~0.07	0.03~0.07	0.02~0.07	0.02~0.07	0.03~0.07
3-4.5	0.09~0.11	0.09~0.11	0.09~0.11	0.09~0.11	0.09~0.11	0.09~0.11
5-6.5	0.12~0.14	0.12~0.14	0.12~0.14	0.12~0.14	0.12~0.14	0.12~0.14
7-8.5	0.15~0.16	0.15~0.16	0.15~0.16	0.15~0.16	0.15~0.16	0.15~0.16
9-10.5	0.17~0.18	0.17~0.18	0.17~0.18	0.17~0.18	0.17~0.18	0.17~0.18
11-12.5	0.19~0.2	0.19~0.2	0.19~0.2	0.19~0.2	0.19~0.2	0.19~0.2
13-14.5	0.21~0.22	0.21~0.22	0.21~0.22	0.21~0.22	0.21~0.22	0.21~0.22
15-16	0.23~0.25	0.23~0.25	0.23~0.25	0.23~0.25	0.23~0.25	0.23~0.25

Flat Head Drill

As the name suggests, a flat head drill is designed with a flat head, making it suitable for a wide range of applications such as drilling on slopes, curved surfaces, countersunk holes, off-center holes, and thin materials. It minimizes burrs and offsets, allowing for straighter and more stable drilling, and it often features a low helix and low rake angle design. This helps prevent workpiece binding and improves surface roughness, eliminating the need for secondary operations to achieve a flat bottom hole.

Drill Bit Type：Solid Carbide Drill Bit
Drill Bit Material：MG Carbide
Drill Bit Coating：AlTiSiN
Suitable Cutting Materials：Carbon steel, low alloy steel, high alloy steel, stainless steel, cast iron, aluminum alloy
Product Models：D425TX-2

Feed Rate Table for Flat Head Drilling

Cutting Material	Carbon Steel	Low Alloy Steel (~24HRC)	High Alloy Steel (~30HRC)	Stainless steel	Cast Iron	Aluminum alloy
Cutting Speed m/min	55~70vc	55~70vc	55~70vc	25~30vc	55~70vc	100~110vc
Drill Diameter（mm）	Feed Rate f(mm/r)
1-1.5	450~473	358~350	318~294	55~53	450~473	636~424
2-2.5	380~395	316~330	268~285	71~57	380~395	875~840
3-4	474~472	474~472	408	186~184	472~470	696
5-7	470~476	470~476	410~420	190~182	507~476	700~740
8-10	435~391	435~391	375~340	165~162	435~391	688~700
11-13	378~360	378~360	324~320	153~148	378~360	682~675
14-16	363~350	363~350	330~300	152~148	363~350	650~588

Conclusion

To excel in metal processing, it is crucial to utilize high-quality and durable tools. Whether in mechanical parts, precision molds, automotive components, aerospace industry, electronic communication, watchmaking, sports equipment, medical devices, or other industries, having reliable and precise drills can significantly enhance productivity. Seven Horse Technology is a specialized manufacturer of cutting tools. We carefully select tungsten carbide materials from around the world to create high-performance, high-precision, and highly stable drilling and cutting tools. Our drill product lineup includes spot drills, micro drills, high-speed drills, flat head drills, and more, catering to different specialized techniques. For instance, our drills feature nanoscale multilayer coatings such as AlTiCrN, AlTiN, AlTiSiN, which effectively extend the tool lifespan. We have also developed high chip evacuation cutting head designs and implemented center water outlet holes for high-speed drilling to reduce cutting point temperature. From tool development, design, prototyping to mass production stages, our professional team is dedicated to providing the best drilling solutions with top quality and cost-effectiveness. If you have any product requirements, please feel free to contact us！

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