When drilling, the right drill bit is crucial. But beginners, in particular, can quickly become overwhelmed: metal drill bits, wood drill bits, masonry drill bits – which is the right one? We'll shed some light on the subject. Our drill bit dictionary provides you with clear explanations and practical tips that will surprise even professionals.

First orientation: Basic drill types

Basically, drills are divided into three categories:

• metal drill

• wood drill

• Stone drill bits (including concrete drill bits)

How do I recognize the different types of drill bits?

Feature 1: Material and lace

• Metal drill bits: Made entirely of high-speed steel (HSS), with a spiral shape and pointed grinding between 118° and 135°.

• Wood drill: centering tip, made entirely of tool steel.

• Masonry drill: Hard metal tip, soldered into a steel shaft.

Feature 2: Shaft shape

• Cylindrical shank: For drilling machines and pillar drills.

• Hexagon shaft: For cordless screwdrivers.

• SDS shank: For hammer drills and impact drills.

Overview of all important drill types

Metal drill bits (HSS drill bits)

The classic twist drill for metalworking. Applications: steel, aluminum, brass.

Stainless steel drill bits (HSS-E)

Specially designed for hard materials such as stainless steel, with a longer service life thanks to the cobalt content.

stone drill

For masonry and brick. Carbide tip for robust work.

Concrete drill (SDS hammer drill)

Optimized for hammer drills, ideal for concrete and hard building materials.

wood drill

Standard wood drill with centering tip, suitable for clean holes in wood materials.

Forstner bit

Perfect for flat and precise holes, e.g. when assembling furniture.

Auger drill

With pull-in thread for deep holes without slipping in hard and soft wood.

Sheet metal cone drill

Ideal for thin sheet metal, drilling holes of different sizes in one step.

Step drill

Multiple drill diameters in one tool, ideal for metal and plastic panels.

Hole saw (can drill)

Large diameters, shallow depth: wood, plastic, plasterboard and thin sheet metal.

Diamond hollow drill

For extremely hard materials such as granite, tiles and glass.

glass drill

Special spoon-shaped tip, perfect for glass and ceramics.

Center drill

Short and precise for drilling, especially in metalworking.

core drill

Cuts only at the edge, particularly efficient for larger metal holes.

Combination tap

Drilling and tapping at the same time – saves time and work steps.

Milling drill

Combination of drilling and milling, ideal for reworking in wood and plastic.

Spot weld drill

For removing weld spots in body construction.

Formwork drill

For drilling through formwork and concrete residues.

HSS / HSSG

HSS is the abbreviation for high-speed steel. It is used as a quality indicator for a drill bit, often in combination with the abbreviation G or R. HSSG / HSS-G stands for ground, and HSSR / HSS-R for rolled. High-speed steels are high-alloy tool steels produced in vacuum arc furnaces. These steels are also hardened at temperatures around 1300°C and undergo three subsequent tempering processes. Due to the higher material hardness, HSS steel is particularly suitable for the production of cutting tools. High-speed steels are available with different alloy proportions, which can then lead to different tool properties.

Core drilling

The hole for a thread is called a core hole, and the drill bits with the corresponding diameter are called core hole drills. For metric standard threads DIN 13, the core hole diameter is generally equal to the thread diameter minus the pitch in mm. Please ensure that the dimensions are correct and always measure the hole before cutting the thread. If the core hole is pre-drilled too small, the following can happen: the tap will jam and break.

Important: For blind holes (bore closed at the bottom), the core hole must be pre-drilled deeper than the desired thread by the chamfer length.

CV / Chrome Vanadium Steel

Chrome-vanadium steel is a steel alloy with the metals chromium and vanadium added. The abbreviation is CV. Vanadium provides increased toughness with a finer microstructure. The chromium content improves hardenability and corrosion protection.

DIN

DIN is the abbreviation for German Institute for Standardization, based in Berlin.

HM / hard metal

HM stands for hard metal. It is produced as follows: Tungsten carbide, cobalt, and titanium are mixed, pressed into sheets, and "baked" in a furnace at 1400 to 1600 degrees Celsius. The technical term for this process is sintering.

SDS plus

SDS is a term for the hammer drill bit holder in a hammer drill with a special design of two grooves. The SDS plus system has a standard shank diameter of 10 mm. The advantages are obvious: quick tool changes and good power transmission. SDS-max (18 mm) and SDS-quick (6.5 mm) are variants of this shank holder developed by Bosch for larger and smaller diameters, respectively.

Drill

Drilling is the creation of a round hole in a material using a cutting tool that is rotated and advanced. Drilling requires a metal drill bit, wood drill bit, masonry drill bit, etc.

cylindrical shank

The cylindrical shank is a round shank and fits all three-jaw chucks and the so-called keyless chucks.

Cutting speed

The cutting speed is specified in meters per minute (m/min). It depends on the material being machined (e.g., structural steel), the material of the cutting tool (HSS or carbide), and the type of process (drilling, reaming, or threading).

The exact calculation of the cutting speed as well as a free table are available for download here : https://gewindeaufschneider.de/blog/schnittgeschwindigkeit/

Tip angle of the twist drill

The point angle of a twist drill is located at the tip of the drill bit. The point angle ensures that the drill bit is aligned and centered when it is inserted into the material. There are different point angles. The point angles can be 118 degrees, 130 degrees, or even 135 degrees. For unalloyed steels with a particularly high degree of purity (stainless steel), a large point angle should always be selected. 135 degrees is particularly recommended for stainless steel. For soft materials, such as aluminum, a twist drill with a point angle of 118 degrees is sufficient.

Spiral angle/ helix angle of the twist drill

The tip angle of a twist drill is also called the helix angle.

Main cutting edges of the twist drill

The main cutting edges of a twist drill perform the actual drilling process. A twist drill always has two main cutting edges connected by a chisel edge. Longer cutting edges provide greater cutting performance compared to shorter ones.

Cross cutting of the twist drill

The chisel edge is located in the center of the drill tip and has no cutting effect. However, it is essential to the design of the twist drill because it connects the two main cutting edges. The chisel edge is responsible for penetration into the material and exerts pressure and friction on it.

PGM

PGM = Testing Association for Masonry Drills

HSS-R

The R stands for roll-formed. The drill's helix is ​​hot-formed, meaning it's red-hot.

HSS-G

The G stands for ground. The drill's helix is ​​ground from solid material.

HSS-E

The E stands for a high-speed steel with at least 4.5% cobalt or at least 2.6% vanadium. These steels are more heat-resistant but also more brittle.

HSS-PM

PM stands for powder-metallurgical high-speed steels. They are purer than conventional steels made from traditional ingot castings.

Impact drilling

With a so-called impact drill, you can drive the stone drill forward in the hole with light blows.

Hammer drilling

The hammer drill bit works its way into the material with powerful impacts. Special hammer drill bits with SDS chucks are available for this purpose.

Rotary drilling

In contrast to hammer drilling and percussion drilling, rotary drilling is carried out without additional impacts.

Tapping

The term "tapping" is misleading. A tap doesn't actually drill, but rather cuts the thread into an existing core hole.

DIN 338

This is the standard for short twist drills with cylindrical shanks. Other applicable standards are DIN 1414 (twist drills made of high-speed steel) and DIN 1414 (drivers on tools with cylindrical shanks).

CBN

CBN stands for Cubic Boron Nitride. It is the second hardest material in the world after diamond. It was invented by the American company General Electric. The term "CBN ground" is often used to describe drill bits. This is intended to convey the message that these tools have a higher surface quality. CBN grinding wheels do indeed offer advantages when machining high-alloy steels. They have high thermal conductivity and a low coefficient of friction.

Tips for the right choice

• Always check first what material you want to drill.

• Make sure you choose the right shaft shape for your machine.

• Use quality drill bits – they save time, effort and money in the long run.
  
  

This glossary is updated regularly. Check back regularly to stay up-to-date. If you have any specific questions, our team of experts at Bohrer-Outlet will be happy to help!

[update on April 14, 2025, SB]