4 Advice to Choose a drill bits for drilling steel

Author: Liang

Aug. 04, 2025

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How To Choose The Right Drill Bit For Metal | Travers Tool Co.

Check out our latest video, and learn how to select the right drill bit to use for the job. Take the guesswork out of drilling holes in metal, as Kurt Repsher walks you through our recommendations for drilling hardened or stainless steels, mild or carbon steels, and aluminum. Subscribe to our channel to see more exclusive how to videos and tips from the pros.

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Selecting The Right Drill Bit

BEST DRILL BITS FOR Aluminum:

Recommended drill bits for aluminum:

Rushmore USA's Solid Carbide Jobbers Length Twist Drills

Precision Twist Drill's Bright Finish High Speed Steel Jobbers Length Drills

Aluminum is very easy to machine, but it’s abrasive, so cutting tools will tend to wear quickly. The best drill bits for aluminum are solid carbide because solid carbide is very hard and stays sharp much longer than other materials, providing extended tool life. If you’re only poking a few holes, high speed steel (HSS) is fine. Using a cobalt drill bit isn’t worth the extra cost because on aluminum, its performance level is about the same as that of high speed steel. Skip the coatings on these drills —there’s no need to increase the already high cost. Especially avoid any coating with “Al” in the ingredients (AlTiN, TiAlN, etc.). A drill bit with a bright finish is ideal.

PRO TIP:

Try to avoid the cheapest drill bits, or you could likely end up spending more in the long run. Always use cutting oil or coolant for any drilling operation.

BEST DRILL BITS FOR MilD STEEL (carbon STEELs):

Recommended drill bits for mild steel or carbon steels:

Viking's M42 135° 8% Cobalt High Speed Steel Jobbers Length Drills

Precision's 135° Split Point Bronze Oxide Cobalt Jobbers Length Drills

TTC Production's TiAlN Coated High Speed Steel Jobbers Length Drills

A good quality High Speed Steel (HSS) drill bit is suitable for use on mild steels, but if you need to get a lot of use from them, go with M35 cobalt drills, or even the aforementioned M42 cobalt drills.

Coatings are helpful when drilling into mild steel, as they:

Add a higher level of hardness to the tool’s surface.
Increase lubricity, which helps with the chip evacuation.
Allow increased feeds & speeds .

BEST DRILL BITS FOR HARDENED STEEL OR STAINLESS STEEL:

Recommended drill bits for hardened steel or stainless steel:

Viking's M42 135° 8% Cobalt High Speed Steel Jobbers Length Drills

Goto GSR to know more.

Additional reading:
Screwdrivers: Parts, Materials, Types & Application (A ...

Precision's 135° Split Point Bronze Oxide Cobalt Jobbers Length Drills

Cobalt drill bits are best suited for use on hard to machine metals, including hardened or stainless steel. Cobalt is blended in with High Speed Steel to make the drill bits harder and more wear resistant. As each cobalt drill bit consists of High Speed Steel with a small percentage of cobalt, the higher the percentage of cobalt, the more heat-resistant and durable the drill bit is.

High speed steel cobalt drill bits: contain 5%–8% cobalt
M35 steel cobalt drill bits: contain 5% cobalt
M42 steel cobalt drill bits: contain an 8% cobalt blend, allowing you to drill at higher speeds than M35 cobalt drill bits

When drilling hardened or stainless steel, select a drill point of at least 135° or higher. This spreads the workload out over a larger cutting surface. Since hardened steel and stainless steel are both quite difficult to drill into, using a drill press or a milling machine should provide the best results.

PRO TIP:

Stainless steel can actually ‘work harden’ as it heats up—so keep your cool, take your time, and make sure the tool and work area stay well lubricated.

Need additional assistance selecting the right drill bit for your workpiece material or application? Contact our tech team!

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We believe the Right Tool Is Everything™, and we strive to share our experience and expertise in an effort to ensure you select the right tool for your application, follow best practices, and can push your productivity further.

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Drill Bits Buying Guide - Lowe's

Drill Bit Materials and Finishes

The materials from which bits are manufactured and the finishes applied to them play a significant role in the life and performance of the bit. Common materials and finishes include:

High-speed steel (HSS) drill bits can drill wood, fiberglass, polyvinyl chloride (PVC) and soft metals such as aluminum.
Cobalt drill bits are extremely hard and dissipate heat quickly. They're mostly used for boring in aluminum and tough metals such as stainless steel.
Black oxide-coated HSS drill bits have a finish designed to help resist corrosion and increase durability. They last longer than basic HSS bits and work well on a variety of materials including metal, hardwood, softwood, PVC and fiberglass.
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. They're effective for drilling tile and masonry.

Drill Bit Construction

For most drill bit types, the angle of the point helps determine what type of material the bit can drill. Flatter points, such as those with 135-degree angles, are suited for drilling into harder material. They may require a pilot hole to keep the bit from wandering. Bits with steeper points, such as those with 118-degree angles, are suited for softer material. They stay on center better and produce cleaner entry and exit holes. Bits with split-point tips improve drilling accuracy by keeping the bit from wandering when you begin to drill.

Bit size reflects the diameter of the body. Some projects call for specific drill bit sizes, but a bit set that includes sizes from 1/16 inch to 1/4 inch will work for many jobs around the home and workshop. You can add larger bits — 5/16-inch, 3/8-inch, 7/16-inch and 1/2-inch bits — if you need them.

The chuck on a hand drill or drill press secures a drill bit to the tool along the bit's shank. A smaller drill for work around the house typically has a 3/8-inch chuck. More powerful drills for heavier applications have a larger, 1/2-inch chuck. Drill presses also have larger chucks, 1/2 inch or 5/8 inch, for example. The bit shank size must not exceed the chuck size of the drill. A larger bit may have a reduced shank — a shank with a smaller diameter than the body of the bit — allowing you to use it with smaller chucks.

A round shank allows you to accurately center a bit in the chuck.
A hex shank has flat surfaces, allowing the tool to grip the bit more securely for greater torque. Hex shanks such as the one in the image above work with quick-change chucks — common on cordless drills — allowing you to insert and remove them without tightening and loosening the chuck.
A slotted drive system (SDS) shank is designed for use on a hammer drill. It fits a spring-loaded chuck that doesn't require tightening. The bit can move forward and backward with the hammering motion of the drill, while flattened areas and slots on the shank allow the chuck to hold the bit.

How to Choose the Right Drill Bit

When deciding which size and type of drill bit you need for the job, take into consideration the size of hole you want and the material you’re drilling into. In most cases, you should drill a hole slightly smaller than the diameter of the screw you’re using so the threads of the fastener have something to cut into. For example, you would need a drill bit with a 2 mm diameter for a 2.5 mm screw. For wall anchors, use a drill bit with the same diameter as the anchor.

When pondering metal vs. wood drill bits or any other types, you’ll need to choose a bit that’s designed specifically for the material. For example, drill bits for wood are not intended for drilling into steel.

Drill Bit Maintenance and Lubricants

Drill bits are tough power tool accessories, but they can wear and become damaged without proper maintenance and care. There are several things you can do to maintain your drill bits and keep them working effectively:

For more drill bits for drilling steelinformation, please contact us. We will provide professional answers.

Keep your drill bits clean. Remove loose debris with a soft brush or cloth.
Use the right type of drill bit for your application. Using the wrong drill bit for a material is a safety hazard. It can also damage the bit, the workpiece and the drill.
Store your bits in a dry location where they’re protected from accidental damage. Storing bits in a drill bit case or using divided storage trays and magnetic holders helps minimize the risk of damage.
Use a cutting tool lubricant when necessary. Drilling into metal generates lots of heat and the heat can shorten the effective life of a bit. Using a cutting tool lubricant can help your bits last longer and let you drill into metal faster.
If you do a lot of drilling, you might want to invest in a drill bit sharpener. This tool uses a grinding wheel to sharpen the cutting edges of many types of drill bits.
Inspect a drill bit before using it. Replace the bit if you find any damage — don’t use a damaged drill bit.