Cobalt drill bits are used for drilling hard metal and steel. They dissipate heat quickly and are highly resistant to abrasions, making them better for drilling into hard metals than black oxide- or titanium-coated drill bits.
Clearly, the best drill bits for hardened metal or steel come with a cobalt blend. These cobalt drill bits use an alloy including 5%–8% cobalt. This cobalt makes up part of the steel blend, so the hardness of the bit doesn't wear off with a coating (like titanium bits). It runs throughout the entire bit.
When drilling through hardened steel, you must ensure that your drill bit is made from tougher materials. Carbide bits are the strongest drill bits material and can cut through hardened steel. But if they are not available, titanium and cobalt drill bits can also be used.
Drill through the metal at a slow, steady speed.
You can use drill bits smaller than 1⁄16 inch (1.6 mm) up to a speed of 3,000 RPM. If you're working with a drill bit that's larger than 1⁄2 inch (1.3 cm), keep it around 1,000–1,500 RPM.
What is the best drill bit for metal? Conventional drill bits cannot cut through metal so you need a heavy-duty, hard drill bit. Two types of drill bits are suitable for metalworking jobs: titanium and cobalt.
Cobalt drill bits are the best drill bits for hard metals including stainless steel. If you are using a hand drill then a 5% (M35) drill bit will be most suitable and it will be less brittle than other drill bits.
Not only does carbide provide cutting speeds at least four to eight times that of cobalt, but far higher feedrates as well. And because carbide drills also support a feature unavailable with their cobalt cousins—coolant through-the-tool—there's no need to peck.
Carbide: The hardest and most brittle of the drill bit materials, it's used mostly for production drilling where a high-quality tool holder and equipment is used. It should not be used in hand drills or even drill presses. These bits are designed to drill into the hardest materials.
Run your drill on the slowest setting when drilling through harder materials. You can get away with a faster speed on things like wood, but metal needs to be drilled slowly. The most critical issue that kills the most drill bits is speed.
The diameter of the hole you drill should be slightly smaller than the diameter of the screw. So, for example, if you're using a 3.5 mm screw, use a drill bit with a diameter of 3 mm. If you're using wall anchors as well as screws, the drill bit and anchors should have the same diameter.
1) Metal drill bits
These include aluminum, copper, brass, zinc, iron and non-alloy steel. Drills made of cobalt-alloy High Speed Steel (HSS-E) or even drill bits with a titanium coating are needed for stainless steel.
It drills through most metals just fine. I don't know if you know it or not but in cordless drills,voltage is power. That is, the higher the voltage, the higher the power. So 20 volts is plenty powerful to drill through most metals.
Gold ferrous drilling tools accompany a sharp point, which is by and large called the pilot point. This pilot point performs and gives its best in puncturing materials like wood or bona fide metal.
If you will be working with hard metals, like cast iron and stainless steel then cobalt bit is the bit for you. Its superior durability and the ability to sharpen the bit makes it the right choice. If you're going to be working with softer metals and wood, then you won't go wrong with a titanium drill bit.
Titanium-coated HSS drill bits produce less friction. They're tougher than basic HSS bits and stay sharp longer. They work for drilling wood, metal, fiberglass and PVC. Carbide-tipped drill bits stay sharp much longer than steel, HSS or titanium bits.
DIYers looking for general-purpose drill bits prefer cobalt drill bits over black oxide and titanium nitride bits for improved durability. A standard titanium nitride or black oxide drill bit can drill holes in aluminum and steel, but their flutes and tips won't stay sharp for long.
These bits are roughly five times harder than steel. With that said, their strength can also make them brittle, meaning that they can break if not used correctly.
Cobalt drill bits are used for cutting hard alloy steel, tool steel, cast iron, and aluminum alloys. In addition to metals, they can also cut soft materials. However, they are not made to cut soft materials like wood or plastic. For precise drilling through wood, you'll need separate wood drill bits.
Material Metal drill bits tend to have a black or gold finish while most wood drill bits only have a shiny silver finish. Metal drill bits need extra strength and heat resistance so they don't get damaged when you use them, so they're coated with a stronger metal, like titanium or black oxide.
Pro Tip: Drilling into metal materials can add extra wear and tear on bits, even those designed for metal. Adding a lubricant such as WD-40® Multi-Use Product can reduce friction and allow for easier drilling and cutting into metallic parts.
Drill at a Slow Speed
The faster a bit spins, the hotter it gets. And heat dulls bits quickly. In general, it's a good idea to drill through metal using as slow a speed as possible using a drill bit for metal. Hard metals like steel and larger drill bits require even slower speeds.