When we consider Cobalt Vs HSS drill bits, we can see a clear difference between them. Both are used for tough drilling tasks such as drilling steel, cast iron, stainless steel, etc. When you select one of them you should know which one is suitable for your task. So let’s compare all detail under 08 facts.
Cobalt Vs HSS Drill Bit Comparison Table
When we compare cobalt vs HSS drill bits, we have to consider each feature of the drill bits. Below table includes summarize detail about the Cobalt and HSS drill bit comparisons.
| Cobalt Drill Bits | HSS Drill Bits | |
| Color | Dark golden amber finished | Bright fnished |
| Manufactured material | High-speed alloy steel, which contains 5%-8% cobalt | ➤ Tungsten – 15% ➤ Chromium – 5% ➤ Vanadium – 1% ➤ Carbon – 0.7% |
| Applied coating | There is no outer coating. | Bright finished |
| Market price | Expensive than the HSS drill bits. $10 – $200 | Economical than the Cobalt drill bits. $7 – $60 |
| Usage | Cobalt drill bits are mostly used to drill the hardest metals. | HSS drill bits are mostly used to drill soft materials. |
| Utility | Cobalt drill bits are less multipurpose. Because can not drill the plastic and wood by using Cobalt drill bits. | HSS drill bits are more multipurpose. Because this can br used to drill hard metals, wood, plastic, etc. |
| Required RPM | 500 RPM | RPM = (3.8197 / Drill Diameter) x SFM |
| Hardness | 65HRC (approximately) | 60 HRC – 68 HRC (approximately) |
| Sharping | Sharping process is easier than the HSS drill bit because there is no any outer coating. | Sharping process is a little bit more difficult than the Cobalt drill bit because there are several outer coatings. |
| Brittleness | Cobalt drill bits break easily. Because it is more brittle. | HSS drill bits don’t break easily because it is more elastic. |
| Thermal resistance | Thermal resistance is high than the HSS drill bits. | Thermal resistance is less than cobalt drill bits |
| Durability | Durability is high than the HSS drill bits. | Durability is less than cobalt drill bits. |
You May be Interested to Read About
- Cobalt Vs Titanium Drill Bits
- Black Oxide Vs Cobalt Drill Bits
- Cobalt Vs Carbide Drill Bits
- HSS vs. Carbide Drill Bits
Features of Cobalt Drill Bits
1. Color
- Dark golden, Amber finished
Color is one way to identify the Cobalt Drill Bits.
- Cobalt drill bits are burned during the manufacturing process. Accordingly, this color occurs during the manufacturing process. Therefore, this color is not plating or paint.
2. Manufactured material
High-speed alloy steel which contains 5%-8% cobalt. Accordingly, this is not made by using pure cobalt.
This alloy has high:
- Hot corrosion resistance
- Melting point
- Thermal weldability
- Fatigue resistance
Therefore, these Cobalt Drill Bits are tougher and stronger for the hardest metals. Moreover, it has a longer life because of this material.
Cobalt drill bits can be divided into different types according to the percentage of cobalt in the drill bit. For example:
- M35 – Contains 5% cobalt (approximately)
- M42 – Contains 8% cobalt (approximately)
3. Applied coating
Cobalt Drill Bits have no outer coating. Therefore, these drill bits are easy to sharpen. Accordingly, it is led to prepare a sharp drill bit easily. Moreover, it has high efficiency. Because there is no coating to be peeled off. That led to an increase in the efficiency of this drill bit.
Drill bits coatings can increase the durability of the tool and decrease friction, resistance, and thermal resistance. So you should pay attention when you buy a drill bit with coating.
4. Market price
Generally, cobalt drill bits are more expensive. Although, it is better than most other types of drill bits.
5. Usage
As mentioned earlier, Cobalt drill bits are tougher and stronger for the hardest metals such as:
- Stainless steel
- Cast iron
- Non-Ferrous
- Bronze/Brass
- Aluminum Alloys
- High Silicon
- Copper
- High-temperature alloys
- Nickel Base
- Titanium
- Welding seams
Moreover, this can be used under conditions such as high temperatures. Because it has high boiling as well as melting points.
However, this does not applicable for general applications such as light metal, wood, and plastic. Because cobalt drill bits are brittle. Therefore, it can break easily. Moreover, this is not good for the use drilling of the concrete.
6. Required RPM
- 500 RPM (approximately)
7. Hardness
- 65HRC (approximately)
Cobalt drill bits are harder than most other types of drill bits. Moreover, these drill bits do not get the hardness by using the coating.
Because there is no coating, accordingly, it gets the hardness from the entire material. Therefore, its hardness is uniform. However, it is also brittle. Because if the cobalt content is higher and the harder it is, the more likely it is to break.
These are the 09 reasons for the drill bits breaking. So avoid these things in your drilling process.
8. Sharping
Cobalt bits can sharpen again and again. That is better to do that before drilling some material. Because that is led to drilling more efficiently and effectively.
Moreover, that is also economically sound. Because there is no need to buying a new bit. However, sharping tools are a little bit expensive. Additionally, broken parts of the drill bit can damage the user and take a long time to finish.
Therefore, sharpening these bits at the required time is really important in many ways. Because that ensures maximum results and does the task timely manner. There are several steps in the re-sharpening process.
This is my favorite method for sharpening drill bits.
Features of HSS Drill Bits
1. Color
- HSS drill bits are color in black (Most of the time), Bright, Amber finished, Ti-Coated
This is the best way to identify the drill bits. This color helps to:
- Increase the thermal resistance
- Increase the abrasion resistance
There is use some special coatings also such as TiN, TiCN, TiAIN
2. Manufactured Material
Simply, it is high-carbon steel. However, this HSS alloy contains several elements, such as:
- Tungsten – 15%
- Chromium – 5%
- Vanadium – 1%
- Carbon – 0.7%
Although, these percentages vary according to the types of HSS drill bit. For example:
| M1 | M2 | M7 | |
| Tungsten | 1.5% | 6% | 17.5 |
| Chromium | 4% | 4% | 4% |
| Vanadium | 1% | 1.9% | 2% |
| Carbon | 0.8% | 0.85% | 1% |
Hardness can be varying according to these material proportions. Most of the time, HSS drill bits are made with M2 type.
3. Applied Coating
There are several coatings applied in these HSS drill bits. Those are:
- Titanium Nitride – TiN
- Titanium Carbon Nitride – TiCN
- Titanium Aluminum Nitride – TiAIN
These coatings are led to an increase performance. Because by using these coatings can:
- Increase the heat resistance
- Increase the durability of the drill bit
- Reduce the friction of the drill bit
- Prevent corrosion
Enhance the durability of the drill bit.
4. Market Price
This HSS drill bit is cost-effective.
5. Usage
These HSS drill bits can be used to drill several sizes of holes on different materials. Generally, these HSS drill bits are used to drill soft materials. For example:
- Mild steel
- Cast iron
- Aluminum
- Fiber
- Plastic
- Brass
- Hardwood
- Softwood
Moreover, this is can also use to drill the hardest metals if the drill bits are coated. For example:
- Cast iron
Although, usage of HSS drill bits varies according to the type. For example:
| Type | Usage |
| M1 | General purpose |
| M2 | Knives, Twist drills, Taps, Broaches |
| M7 | Heavy construction equipment |
6. Required RPM
Users need to know about the SFM (Recommended speed) to calculate the RPM. Accordingly, RPM can be calculated by using:
RPM = (3.8197 / Drill Diameter) x SFM
Accordingly, this table gives the SFM of a few materials.
| Material | SFM |
| Brass | 150 – 300 |
| Aluminum | 200 – 300 |
| Plastic | 100 – 300 |
8. Hardness
- 60 HRC – 68 HRC (approximately)
As mentioned earlier, hardness can be varying according to these material proportions. Moreover, the hardness of HSS drill bits also depends on the process of heat treatment.
9. Sharping
HSS drill bits can be easily sharped. There are a few conditions under which the user may recognize that drill bits must be sharp. Those are:
- Drilled holes are out of the tolerance
- Produces more noise when drilling
- Chipping length is below 0.02
The user can use a carbide grinder, diamond grinder, bench grinder, or a file to sharpen the drill bits. Although, the user should to consider and maintain the cutting angle the most. Because the cutting angle varies according to the material requirement, there are three types of angles.
When you use a drill bit you can see at least one of these 08 problems of drill bits. I have listed all 08 drill bit problems and solutions here.
- Point Angle
- Helix Angle
- Lip Relief Angle
This table gives the details of how much needs to be sharp in the angles of a few materials.
| Brass | Aluminum | Plastic | |
| Point Angle | 90 – 118 | 90 – 135 | 60 – 90 |
| Helix Angle | 0 – 20 | 32 – 48 | 0 – 20 |
| Lip Relief Angle | 12 – 26 | 12 – 26 | 12 – 26 |
It is necessary to sharpen the drill bits at the right time. Because dull drill bits are led to overheating, accordingly, it is led to reducing efficiency. Moreover, it is economically sound if the user sharpens the drill bits at a right time because the re-sharping process helps to extend its life.
A drill bit will hot due to these 09 reasons and you can cool the drill bit using these 07 tips
HSS or Cobalt Drill Bit – Which One Do You Need?
Accordingly, there are several factors is need to be considered before purchasing a drill bit. Initially, the user must consider what material is going to be drilled.
Moreover, the user should also consider their budget. However, HSS drill bits are multipurpose. Because it can drill steel and even plastic and wood. Furthermore, cobalt drill bits are more durable than HSS drill bits.
Heat is generated during the drilling operation. Cobalt drill bits have higher heat resistance than the HSS drill bits. Therefore, the sure should also consider the heat resistance.
Additionally, the user should be careful about their safety while using these. For that users can wear protective goggles, face shields, and gloves.
Therefore, choosing a drill bit is a little bit difficult. It is the user’s responsibility to choose the right drill according to their needs, use it correctly and cleanly and sharpen it at the right time.
