A carbide drill bit is a masonry drill bit. It has made with mixing tungsten and carbon. Normally, a carbide drill bit has a hardness of 70+ HRC, and it can be used to drill the hardest material like concrete, tile, stones, etc. Carbide drill bits are highly thermal resistant and friction resistant. Carbide is used as a cutting edge of a drill bit.
Carbide drill bits are more expensive than other drill bits. Hence its cost per hole is very low with considering other drill bits. As well as you can use a long run from single sharpening.
How Is Carbide Drill Bit Made?
The Carbide drill bit is made with tungsten and carbon mixing. Tungston is a really hard material, and its hardness has increased by adding carbon. In order to reduce the interaction with iron, cobalt is mixed with carbide.
Carbide Drill Bit Compare with Steel
| Properties | Steel | Tungsten Carbide |
| Melting point | 1,370 °C (2,500 °F) | 2,870 °C (5,200 °F) |
| Boiling point | 2,800 °C (5,072 °F) | 6,000 °C (10,830 °F) |
| Thermal Expansion | 11.0 ~ 13.0 µm·m−1·K−1 | 5.5 µm·m−1·K−1 |
| Hardness | 4-4.5 Mohs scale | 9-9.5 Mohs scale. |
Using this table, you can realize how hard is the tungsten carbide material.
Usage of Tungsten Carbide
Due to its high toughness, it is used for cutting materials. Most drill bits, and cutting tools are made with tungsten carbide. Hammer drill bits are made with tungsten carbide to resist the hammering function, thermal resistance, and wearing resistance during the drilling process. There are other materials for the drilling process, such as cobalt, HSS, and Titanium.
Carbide Drill Bit Structure
➤ Carbide Drill Bit Shank
A drill bit shank is named as the driving end of the drill bit. According to the purpose of the drill bit, shank geometry can be varied. Mostly, carbide drill bit shank is 4 rails or 5 rails. These bits are named as SDS plus and SDS max drill bits. And also, we can see circular and hex-shaped shanks in light hammer drills. But rail-structured carbide drill bits are used on rotary hammers.
➤ Carbide Drill Bit Flute
Normally, the drill bit flute design is spiral. It has designed to remove inside debris through the flute. The carbide drill has an expanded flute design. As a result of this, it can transfer more debris to the outside, even at lower RPM.
➤ Carbide Drill Bit Cutting Head
The carbide drill bit cutting head has 2 edges, 4 edges mainly. In some special cases, it has 5-6 cutting heads. The material can crush into powder when the cutting head has more edges. As well as, these bits are stronger than regular cutting heads. Hence these bits can be used to drill different materials like concrete and rebars together.
Carbide Drill Bit Usage and Cutting Speed
➤ Usage
Carbide drill bits can be used to drill harder and tough materials like concrete, stone, tiles (without hammering action), and concrete with rebars. As well as, some carbide drill bits are available for metal, wood, cast iron, titanium, PVC, fiber and plastic, etc. Carbide drill bits can be used as a huge versatile drill bit.
➤ Cutting Speed
When using a carbide drill bit on concrete, you should use lower RPM like 400 – 600 RPM with a hammering action. You can maintain 9000 – 11000 surface feet per minute (SFM). Masonry carbide drill bits are used on rotary hammers; hence, you do not need to apply additional force or pressure for the drilling task. Just push the tool.
Tungsten Carbide and Other Drill Bits
As I mentioned above, cobalt, titanium, and HSS are used for making drill bits. But those are not harder than tungsten carbide. These 09 types of masonry drill bits are highly recommended for your tasks. These can be optional for the tungsten carbide drill bits.
➤ HSS
HSS stands for high-speed steel. It is mostly used for cutting tools, blades, and drill bits. HSS drill bits can be used for wood, plastic, and soft steel drilling. HSS is much faster than the regular steel drill bits. But not as the carbide drill bits. HSS requires more sharpening terms due to abrasion.
➤ Cobalt
Cobalt drill bits are made when 5-8% cobalt is mixed with the steel alloy. These tools can be used to drill hard materials such as cast iron. Normally cobalt is mixed with tungsten carbide to reduce the iron’s reactivity. The cobalt drill bits’ color is dull gold, and it is applied to the outer coatings.
Normally cobalt drill bit can cut 100 holes for one sharpening, and 1000-2000 holes can be drilled with the carbide drill bit from one sharpening.
➤ Titanium
Titanium drill bits are made by applying the titanium layer around the steel drill bit. It is the same as the cobalt strength and performs well until the titanium layer exists. These coatings (TiCN, TiN) can reduce tool friction and increase heat resistance.
➤ Diamond
Diamond drill bits are stronger than carbide drill bits. Diamond is the hardest material in the world, and its dust is used to make the diamond drill bits. Tile, and glass can be drilled using the diamond drill bits easily.
When you use a drill bit longer period, it can be blunt. So you need to sharpen the drill bit. This is the guide I use for sharpening my drill bits.
How to Sharpen a Carbide Drill Bit?
Carbide drill bits are a bit more expensive than other drill bits due to their high strength and durability. It can also be damaged due to unexpected scenarios. When you continuously use the carbide drill bit, its sharpness can be reduced. As a result of this, it should sharpen or replace.
Shapen, a carbide drill bit is always a good solution than it is replacing. If you need to sharpen the carbide drill bit, you must use more strength and hardness grinding wheel. You can use a diamond surface grinding wheel to sharpen the carbide drill bit. A regular grinding wheel cannot be used due to its less hardness.
When should you sharpen the drill bit?
You can sharpen the drill bit if there is a tolerance in the hole beyond the acceptable limit, and when the chippings are below 0.02″, you are ready to sharpen the drill bit.
