When we choose a drill bit, we can see, so many types of drill bits are available in the market. Cobalt and carbide drill bits are both drill bits that we need to use for tough drilling purposes. There are differences in the cobalt and carbide drill bits. So let’s see, what are the differences and similarities between Cobalt Vs Carbide drill bits.
Cobalt Drill Bits
We can summarize all in detail about the cobalt drill bit in the below table.
|Manufactured material||Combination of HSS (High-Speed-Steel) (or another alloy) mixed with a small percentage of cobalt, typically between 5 – 8%. Under that, few drill types can be identified in the market.|
Titanium nitride (TiN) Gold OxideTitanium carbon nitride (TiCN) – Harder than TiN cobalt drill bit
|Applied coating||No coating|
|Market price||Single drill bit $20 -$65|
Drill bit set $50 – $150
|Usage||Can use to cut through harder metals.Such as; bronze, cast iron, stainless steel, and titanium|
|Required RPM||It is depending on the diameter and depth of the required hole. Mainly it requires 500 RPM.|
|Hardness||Approximately 65HPSMoh’s scale value: 7-8|
|Sharpening||It is possible.|
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.
As before mentioned, cobalt mixtures with regular high-speed steel with a small percentage of 5 to 8. M35 cobalt drill bits has produced with 5 presents of cobalt. And also, the M40 cobalt drill bit produced 8 presents of cobalt.
3. Applied Coating
The ambient look and dull gold color are coming from the heat process of the drill bit. Otherwise, there was no external coating. Therefore, it directly affect the resharpening process. Otherwise, it cannot be sharpened like a titanium drill bit, so it cannot be used repeatedly.
Read More About – Drill Bit Material, Coating and Usage – In Depth Guide!
4. Market price
Cobalt drill bits are available in the market as a set. Accordingly, there are drill bits with different diameters in this 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 USD 20 and 65.
As before mentioned 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.
6. Required RPM
It is better to control the drilling speed by the lowest RPM would make drill life much longer than three times.
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; 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.
Read More About – Black Oxide Vs Cobalt Drill Bits – Which One is the Best?
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.
This Drillbit Sharpening guide will help you to sharpen the drill bit properly.
Carbide Drill Bit
|Color||Bright appearance (Can see uncoated drill bits) Yellowish gold|
|Manufactured material||Combination of tungsten and carbon.|
|Applied coating||Uncoated brill bits also can be identified. The various coating can also identify.|
|Market price||Single drill bit – 15$- 45$|
Drill Bit Set – 30$-150$
|Usage||Can use to cut through harder metals. Such as; Concrete, Stone, Bricks. The surface contains steel with concrete together. Non-ferrous heavy metals Fiber-glass reinforced plastics.|
|Required RPM||It is depending on the diameter and depth of the required hole.|
|Hardness||Moh’s scale value: 9-9.5|
|Sharpening||It is applicable|
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
The prices vary by,
- The size of the drill bit.
- The type of external coating
- The manufacturer.
- Single drill bit – 15$- 45$
- Drill Bit Set – 30$-150$
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, several drill bits in the market are suitable for safely drilling hard materials such as concrete. The high hardness of carbide drill bits is very close to the hardness of diamond so it can be used for that.
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
Which One You Should Buy?
Which drill bit we should choose should be considered on several points. Accordingly,
- 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.
Read More About – Choose the Right Drill Bit – Geometry | Coating | Material
|Properties||Cobalt drill bit||Carbide drill bit|
|Color||Dull gold||Yellowish gold|
|Manufactured material||Combination of HSS (High-Speed Steel) (or another alloy) mixed with a small percentage of cobalt, typically between 5 – 8%.||Combination of tungsten and carbon.|
|Applied coating||No coating||Carbide coating|
|Market price||Cheaper than a carbide drill bit.||Expensive drill bit type.|
|Usage||Can use to cut through harder metals. Such as; Bronze, Cast iron, Stainless steel, and titanium and also, can cut the welding seems.||Can use to cut through harder metals.Such as; concrete, stone, and bricks. The surface contains steel with concrete together. Non-ferrous heavy metals Fiber-glass reinforced plastics.|
|Required RPM||~500 RPM||The lowest RPM will help to reach higher efficiency.|
|Hardness||Rockwell scale: ~65HRC Moh’s scale value: 7-8||Rockwell scale: ~75 HRC Moh’s scale value: 9-9.5|
|Sharpening||It is applicable. Regular grinding wheel||It is can but the hardest process. The diamond grinding wheel is needed for this process|
|Brittleness||Brittle than the HSS drill bit.||Brittle than the cobalt drill bit.|
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.
In general, both types of drill bits can be resharpened. Therefore, although it is more expensive compared to HSS, extensions can be used earlier when it suits the need.
The steps in the sharpening process are:
- Please check the drill bit edge
- If it is not sharpened one selects the right tool to sharpen it. – The bench grinder is suitable for this. Although the user must select a suitable wheel. There have two-wheel types. Those are fine coarse wheels.
- Take safety measures.
- Maintain the drill bit angle 60o degrees to sharpen the drill bit.
- When sharpening the drill bit, it should be stopped every five seconds. This reduces the temperature rise of the drill bit. The bit can be held by hand until the job is finished.
- The drill bit should be rotated 180 degrees and steps 4 and 5 mentioned above should be followed.
- Both those two types of drill bits are suitable for hard drilling purposes. Higher hardness of drill bits, lowest RPM, applying suitable lubricant, and resharpening ability mainly affect this purpose.