Hard material drilling is impossible with regular steel drill bits. In order to drill more tough material, carbide drill bits have been made. There are special physical and chemical properties in the carbide drill bits. Let’s see in detail what is a carbide drill bit and its usage in detail below.
Normally carbide drill bits are made by mixing tungsten and carbon. Cobalt is mixed with the mixture to reduce the reactivity with iron. These bits are high resistance to abrasion, thrust, and heat. Carbide drill bits are used to drill stone, concrete, bricks, and many hard materials.
Carbide drill bits are made with different materials. Due to this, it has more hardness and high thermal resistance. More than that, there are some special properties that are really important as a drill bit. So let’s see what those are in detail?
How Carbide Drill Bit Is Made?
The Carbide drill bit is made with tungsten and carbon mixing. Tungston is a really hard material, and by adding carbon, its hardness has increased. In order to reduce the interaction with iron, cobalt is mixed with the carbide.
Carbide Drill Bit Compare with Steel
|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 the 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 the 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.
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Tungston Carbide Compared with the Other Materials.
As I mentioned above, cobalt, titanium, and HSS are used for making the cutting and drilling tools. But those are not much hard considering the tungsten carbide.
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.
When 5-8% cobalt is mixed with the steel alloy cobalt drill bits are made. These tools can be used to drill hard materials such as cast iron. Normally cobalt is mixed with tungsten carbide in order to reduce the reactivity with the iron. Cobalt drill bits’ color is gold like it has applied the outer coatings.
Normally cobalt drill bit can cut 100 holes for one sharpen, and 1000-2000 holes can be drilled with the carbide drill bit from one sharpening.
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 the tool friction and increase heat resistance.
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 blunt. So you need to sharpen the drill bit. This is the guide I use for sharpening my drill bits.
Carbide Drill Bit Structure
Carbide drill bits are not like the common sharpen structure. Mostly carbide drill bits are used to drill hardness material such as concrete, stone, and bricks. Sometimes it can drill steel and concrete together.
In the drilling process, it does the crush the material by punching it. Carbide drill bits are used with the hammer drills. In the hammering mechanism, it moves the drillbit or chuck move forward and backward more than thousands of times per minute will crush the material around the drill bit tip. This rate is called BPM.
Flutes are starting beyond the tip, and it will transfer the drilled debris outside.
Mostly drill bit tip is made with the tungsten carbide in order to reduce the cost. But it will not affect the performance.
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How to Sharpen Carbide Drill Bits?
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 use the carbide drill bit continuously, 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, hardness grinding wheel. You can use a diamond surface grinding wheel to sharpen the carbide drill bit. Using a regular grinding wheel is not able to use 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.
Usage and Cutting Speed of Carbide Drill Bits
You can identify the carbide drill bit by its tip. The tip is a triangular shape, and the flutes start a bit space from the tip. The tip is made with the tungsten carbide, and the rest can be made with the other strong material. Those are not hard than fully tungsten carbide drill bits.
Normally tungsten carbide drill bits are bright finish, and if some coating is applied for special reasons, it can be colored.
Drilling hard material such as concrete required low RPM with hammering action. Most hammer drill bits are made with tungsten carbide, and you can identify these bits by railing shank of the drill bits. These bits are used in the SDS plus and SDS max drill machines.
Read More About – Differences Between SDS, SDS Plus, and SDS Max drills?