Cobalt vs carbide drill bits have extraordinary differences. While cobalt drill bits are made with HSS and different proportions of cobalt. Hence these bits can be used to drill tough materials like stainless steel, cast iron, and other alloys. When considering the carbide drill bits are made with tungsten carbide. Hence carbide drill bits are harder and tougher than cobalt drill bits. Therefore carbide drill bits can be used in a wide range of metals and concrete, stone, and bricks. Both drill bits can be sharpened. But the carbide drill bit need to sharpen rarely. Not only that, carbide drill bit has a lower cost per hole, and cobalt drill bits have a higher price.
Cobalt vs. Carbide Drill Bits Comparison
When considering the cobalt and carbide drill bits, each has different features. When we compare both, we should consider their features. The below table has been prepared by considering the features of the cobalt and carbide drill bits.
|Properties||Cobalt drill bit||Carbide drill bit|
|Color||Dull gold||Yellowish gold/ bright finish|
|Manufactured material||Combination of HSS and cobalt, typically between (cobalt 5 – 8%.)||Combination of tungsten and carbon.|
|Applied coating||No coating for base material||Carbide coating|
|Market price||Single drill bit $20 -$65|
Drill bit set $50 – $150
|Single drill bit – 15$- 45$|
Drill Bit Set – 30$-150$
|Usage||Can be used on Bronze, Cast iron, Stainless steel, and titanium etc.||It can be used for harder metals, concrete, stone, and bricks.|
|Required RPM||~500 RPM||The lowest RPM will help to reach higher efficiency.|
Moh’s scale value: 7-8
|75 HRC |
Moh’s scale value: 9-9.5
|Sharpening||It can resharpen using a regular grinding wheel||It can resharpen using a diamond grinding wheel|
|Brittleness||Brittle than the HSS drill bit.||It can use to cut through harder metals.|
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Features of Cobalt Drill Bits
Normally, cobalt drill bits are dull gold in color. But when it is coated with black oxide or titanium coating, its color is related to the coating color.
When considering the color of the cobalt drill bit, the manufacturing steps should be examined. The HSS drill bits with cobalt must heat to prepare the cobalt drill bit. This process gives an ambient look to the cobalt drill bit.
2. Manufactured Material
When concerned with this topic, it has mainly two types of cobalt drill bits according to the percentage of Cobalt.
Cobalt drill bits are made by combining HSS and Cobalt. When the cobalt percentage is 5% it is rated as M35 drill bits. When the cobalt includes 8%, it is called an M42 drill bit.
When considering M35 and M42 bits, M42 is the hardest and tough one.
3. Applied Coating
The ambient look and dull gold color come from the heating process of the drill bit.
Otherwise, there was no external coating. Therefore, it can resharpen directly. Normally, cobalt is coated with TiN, TiCN, and TiAlN compounds in order to improve its physical properties.
4. Market price
Cobalt drill bits are available in the market as a set and singles. A single cobalt drill bit will cost about $10-$25 and a set will cost more than that. It depends on the sizes and numbers of the drill bits in the set.
Depending on your needs, you can buy the most suitable cobalt drill bit set under the brands available in the market at a price range between $20 – $150.
Everything depends on the quality of the drill bits.
As mentioned before cobalt drill bit is also a harder type of drill bit. And also, it can use even under high temperatures which generate due to the drilling process. Therefore, this can be used for the heavy metal drilling process.
Cobalt drill bits can be used to drill soft metals like aluminum and harder metals like cast iron, stainless steel, and titanium.
6. Required RPM
When you use a cobalt drill bit, you can use below surface speed (SFM) for each metal
|Metal||Surface Speed (SFM)||Metal||Surface Speed (SFM)|
|Low Carbon Steel||110||High-Temperature Alloys||50|
|Medium Carbon Steel||65||Aluminum Alloys||325|
|Medium Carbon and Alloyed Steel||60||Brass||80|
|Tool and Die Steels||50||Bronze||80|
|Cast Iron (Soft grey)||105||Composite plastic||175|
|Cast Iron (grey)||90||Magnesium Alloys||325|
|Cast iron (ductile)||55|
|Titanium Alloys (Pure 99.0)||90|
|Titanium Alloys (C-3, C-4)|
According to Moh’s scale, cobalt is between 7-8. Moh’s scale is a simple concept that can be used to measure the hardness of something. Here, according to Moh’s scale, the ability to squeeze something of unknown hardness compared to things of known hardness is tested.
Cobalt drill bits can be used particularly successfully in soft materials as well as cutting through hard metals such as stainless steel and cast iron.
Cobalt steel increases the strength of these bits and; Heat-resistant. This is an important factor in drilling hard materials because the friction of the bit metal against the hard metal creates high temperatures that damage the material or the drill bit.
Cobalt drill bits are generally a stronger type of drill bit. Its high thermal insulation is also useful when cutting hard metals. Prolonged drilling results in additional damage and wear of the blade. These bits can be sharpened again as mentioned above.
The lack of external adhesive is a big plus. So, these bits are expensive but can be used over and over again for serious tasks like cutting hard metals.
Features of Carbide Drill Bits
The color of these drill bits depends on the coatings. Because different coatings can identify under various manufacturers. An uncoated drill bit has only a bright appearance.
2. Manufactured material
Carbide drill bits are usually made from a mixture of tungsten and carbon, plus a mixture of cobalt to reduce reactivity with iron. It increases its lifespan. Storage is easy. Tungsten is a hard material. Additionally, adding carbon has increased the hardness of the bit.
3. Applied Coating
Some of the carbide drill bits are not coated. Although the carbide drill bits can also coat with various coatings. Those are:
- Aluminum- Tin- Nitrogen
4. Market Price
Carbide drill bits can be considered expensive drill bits in the market. Due to its higher hardness and toughness, it can be used to drill thousands of holes per one sharpening. When using a carbide drill bit, the cost per hole is the lowest value. Because of this, carbide drill bits are expensive and mostly used for professional use.
- A single drill bit will cost 15$- 45$
- The drill bit set will cost 30$-150$
The price depends on the quality of the drill bits.
Carbide drill bits are harder than regular HSS and cobalt drill bits. Therefore, it can use for the different types of the hardest material drilling processes.
Generally, carbide drill bits can be used in a wide range of materials. Mostly these bits are used on CNC machines which require speed drillings. More than that, carbide is mixed with tungsten, and those are used on the masonry drill bits. Due to the higher hardness, carbide drill bits can be used in a wide range.
6. Required RPM
We know that in general, any drill bit typically has a wide range of sizes in the market. When examining the variation of RPM with these sizes, the RPM shows a rapid decrease as the size increases.
As mentioned earlier, the inclusion of tungsten in these bits has helped the hardness of these bits. The hardness of these bits is determined at the highest hardness limit of Moh’s scale. It is between the 9-9.5 range of Moh’s scale.
Carbide drill bits are not easily resharpened.
Sharpening is a time-consuming process. Sharpening these bits requires a special tool and a cutter grinder with a diamond grinding wheel. So often, replacing instead of re-sharpening is an easy and efficient step.
Cobalt or Carbide Drill Bits – Which One Do You Need?
Before you choose the drill bit, you had better pay attention to the below facts.
- The material to be drilled should be examined carefully.
- Its hardness should be considered.
- A drill bit with high work hardness must be selected for a safe and efficient drilling process.
- The diameter of the hole being drilled.
- Drill hole depth – If it is twice the diameter of the drill bit; the user must drill slowly to reduce the heat.
- Also, the type of drill bit suitable for the skill of the user should be selected while performing the task.
The carbide drill bit is the most suitable drill bit in terms of hardness. Carbide drill bits can be used in the gem industry for fine work and in the construction industry for drilling things with high hardness such as concrete.
Normally, carbide drill bits are more expensive than cobalt drill bits. But it can be used in wide range, with higher cutting speed easily. Mostly carbide drill bits are suitable for CNC machines. Cobalt drill bits are suitable for DIY projects. By considering all, cobalt drill bits are the suitable drill bit that we can use for daily work.