Selecting a metal drill: product types, markings and color. What are the best metal drills? Making the right choice What material are metal drills made from?

Metal drill: design, geometry, drill elements. How and from what drills are made. Shank types and markings. Selection, application and storage rules. The best manufacturers and tips for choosing metal drills.

In mechanical engineering, a metal drill is the second most frequently used tool after a cutter, and in the household it confidently shares leadership with a hacksaw and a cutting wheel. Structurally, a drill is a long cylindrical metal rod with two cutting edges at the end and spiral grooves for removing chips. The principle of cutting metal and forming a hole for all types of this tool is almost the same, therefore the main classification of metal drills is based on design features (type of shank, spiral profile, type of cutting edge, etc.). Determine by appearance All the necessary characteristics of the drill are quite difficult, since the markings that are engraved on the metal of the shank contain information only about the diameter of the tool, the material of manufacture and the manufacturer. Therefore, in order to choose a drill for processing hard, brittle or tough metals and alloys, you need to use the manufacturers’ catalogs. Long-term and short-term storage of drills must be carried out according to certain rules, since tool and high-speed steels are prone to corrosion, and sharpened edges are easily damaged when hitting metal.

Any drill, regardless of its purpose and design features, consists of two main components: the shank and the working part. The first serves to transmit rotation to the tool from the drive or to fix it in a stationary state (on lathes). The working part consists of a number of elements that directly support the drilling process. The geometry of the drill depends on the characteristics of the drilling for which it is intended, as well as the material of the workpiece being processed (various metals, wood, plastics, composites, ceramics).

As an example, we take one of the most common types of such tools in industry: a twist drill for metal work with a conical shank (see drawing below). All drill angles shown in the figure correspond to general-purpose metal work. On the left is a side view, and on the right is from the working end (enlarged).

All the main components and geometric parameters of such a drill are listed below with explanations:

Shank. Serves to secure the tool in the machine spindle or chuck. When drilling metal on lathes, it is fixedly mounted in the tailstock cone.
Working part. Forms a cylindrical hole (or recess). It consists of a cutting part, the length of which for such metal drills is usually half their diameter, and a guide with grooves for removing chips.
Morse cone. For installation in spindles and tailstocks of machine tools, a tool with a conical shank is used, and for clamping into jaw and collet chucks, a tool with a cylindrical shank is used.
Paw. These structural elements are present only on tapered shanks and are designed to knock the tool out of the spindle or arbor.
Neck. Provides convenient approach and retraction of the grinding tool when processing spiral grooves. It does not perform any operational functions, so it is usually marked with a drill bit (embossed directly on the metal).
Guide part. Also called calibrating. Relying on the walls of a hole drilled in the metal, it guides the tool along its axis. Includes spiral striped surfaces and flutes for chip evacuation.
The angle of inclination of the spiral surface. For metal processing it is 18÷30°.
Chip removal groove. The speed of chip removal depends on its width, inclination and surface quality.
Diameter of the cutting part. Equal to the distance between the outer edges of the cutting edges.
Cutting edge. This is the sharp edge between the rake face (chip flute) and the back ground surface.
Main vertex angle. The angle between the cutting edges has a significant impact on the cutting process and the strength of the drilling tool. For metal work, its standard value is 116÷118°.
Back surface. To reduce friction in the cutting zone, the rear surface is sharpened at an angle to the cutting edge. To drill metal, its value near the ribbon should be 8÷12°.
Jumper. A structural part common to both rear surfaces.
Transverse cutting edge. A sharp edge on the bridge separating the rear surfaces. With proper sharpening, in the middle there is the geometric center of the cutting part, which should coincide with the axis of the tool.
Ribbon. Two strips slightly protruding above the spiral surfaces, which calibrate the hole and reduce friction against its walls.

The general layout of other types of metal drills is similar to this, although depending on their purpose they may differ in the design of the cutting part and chip removal grooves.

Types of metal drills

The main classification of drilling tools is carried out according to their design, since it is directly related to the purpose of a particular type of metal drill. In addition, within the design types, varieties are distinguished according to the type of material for which the given tool is intended for processing (the so-called cutting groups). There is no strict classification for them, but usually the following types are distinguished based on the type of working part:

spiral;
feathers;
centering;
special.

Among special drills, the largest group is a tool for deep drilling in metal workpieces. Separate subgroups also include products for drilling large diameter holes and stepped cylindrical profiles. It happens that a modern prefabricated tool has such a complex or innovative design that it is classified into several types at once.

Spiral shape

A traditional, widespread type of drilling tool is a twist drill, in which the formation of a cylindrical hole in the metal is carried out by two symmetrical cutting edges. In this case, the removal of the resulting chips passes through spiral grooves, the initial part of which is the front surfaces that form these edges. By design, these products can be monolithic or prefabricated, with a replaceable head or mechanical fastening of cutting inserts. To reduce friction and increase the speed of chip removal, the spiral part is polished and coated with wear-resistant materials.

Step form

Step drills are used to produce shallow-depth holes with fixed step geometry. Such a tool allows you to form two or more cylindrical surfaces in one pass and is most often used in automated processing. By their design, modern step drills, as a rule, represent a monolithic block that repeats the configuration of the future hole, with rows of cutting plates and straight grooves. The first ones drill an initial hole in the metal of the workpiece, and the ones following them are reaming holes. The biggest problem with this tool is chip removal during machining. Therefore, their use is limited to highly specialized areas.

Core drills

A core drill is a hollow tool with a ring arrangement of six or twelve cutting surfaces and a corresponding number of chip removal grooves. It is used for through drilling of large diameter holes in metal. During operation, the cutting edges only cut a ring around the middle of the future hole, and the central part of the metal simply falls out (or is knocked out) after passing through. This tool is classified as a drilling tool, rather, according to an established tradition, since in its operating principle it is much closer to cutters.

Auger drills

When drilling holes in metal to depths that are multiples of 30–40 diameters, elongated drills of a special design with a spiral groove in the form of an auger are used. This solution greatly improves chip removal and allows continuous drilling of metal to the full depth of the hole without periodic withdrawal of the tool. Auger drills differ from conventional spiral drills in the large angles of inclination of the grooves (up to 65°) and their triangular profile. In addition, they have an increased core diameter and a special sharpening of the front surface.

Feather drills

Feather drills are used to make holes in metal covered with casting crust and scale. Structurally, this is the simplest drilling tool, because it has straight grooves and a cutting part in the form of a plate. Its disadvantages are a direct consequence of its simplicity of design and low cost. During the process of drilling metal, feather drills have poor chip removal and tend to move away from the axis of the hole. A plate protruding forward reduces the strength of the entire product, which does not allow working at high feeds, and also requires frequent regrinding. This is a highly specialized tool of increased rigidity, which is used when working with castings and forgings.

Shank types

In accordance with early Soviet GOST standards, which are still in force, two types of shanks were provided for metal drilling tools: cylindrical and conical (Morse). In 1990, GOST 28706-90 was adopted, which duplicated the regulation of ISP 9766-89 for cylindrical shanks with flats. This type of shank is intended for prefabricated metal drills, in which the flat prevents them from turning in the equipment during operation. Now this solution is widely used for modular tools, and where the drill is directly fixed in the spindle, products with a Morse taper are still used.

Marking of drills according to GOST

The rules for marking drills are regulated by GOST 2034-80. According to this document, markings are not applied to drilling tools with a diameter of less than two millimeters. All information about them must be indicated on the packaging label. For drills with a thickness of over two and up to three millimeters, the marking of a metal drill contains only the diameter value and steel grade (thus they can be distinguished from a tool up to two millimeters). For diameters over three millimeters, the manufacturer must indicate its size, its trademark, metal grade and accuracy class as part of the marking. The grade of metal from which the tool is made can be indicated both in the form of the GOST designation of steel (for example, R6M7K6), and the international abbreviation generally accepted for high-speed steels (HSS) with the addition of the designation of the main alloying metal (Co, Ni, Ti, etc.) ( see photo below). Foreign manufacturers mark their products in a similar way, so you can distinguish Russian drills from imported ones only by the trademark.

Color designation

In their catalogs, all leading manufacturers of drilling tools use color markings to designate products, provided for by the international standard ISO 513. In accordance with this regulatory document, all tool materials are divided into six groups, each of which is intended for processing certain types of metals, alloys and polymer materials.

Group	Color	Processed metals and plastics
P	Blue	Selected species carbon, alloy and tool steels. Steels for castings. Some grades of corrosion-resistant steels.
M	Yellow	Austenitic corrosion-resistant steels. Certain types of non-magnetic and wear-resistant steels.
K	Red	Various brands of cast iron.
N	Green	Non-ferrous metals and their alloys. Thermoplastics and duroplasts.
S	Golden	Heat-resistant alloys based on nickel, cobalt, titanium and iron.
H	Grey	Hardened steels of high hardness.

In addition, each cutting group is divided into application groups, which are designated by a number in the range from 1 to 40. Groups with a higher index have higher strength, and with a lower index, greater hardness and wear resistance.

Structurally, a twist drill consists of two main components: the working part and the shank. The first is made of high-speed steel or hard alloys, and the second is made of carbon tool steel. The production of twist drills for metal includes the following enlarged stages:

Preparation of components. Cylindrical blanks for both parts are cut on bar machines and then cleaned of burrs, surface oxides and contaminants.
Welding. Two parts made of different metals are welded using resistance butt welding. After this, excess metal is removed from the welds, and the workpieces are straightened to give them an accurate cylindrical shape.
Turning. The workpieces are centered and ground to the exact size. At the same stage, the ends are trimmed, the shank cone is sharpened, and the end of the cone is ground for the foot (for a tool with a cylindrical shank, the last two operations are absent).
Milling. The foot (for tapered shanks), spiral grooves and flanks are milled. After this, the workpiece is subjected to heat treatment, followed by cleaning in a sandblasting machine.
Grinding. The grooves of the spirals are ground and polished. After this, the shank and working part are subjected to grinding (with finishing of the reverse cone).
Drill sharpening.

The housings of prefabricated drilling tools, in which the cutting part is made of carbide plates with brazed or mechanical fastening, are quite complex products, since their manufacture requires complex milling and turning. Therefore, they are usually made on CNC machines or machining centers.

Metal drill size chart

State standards, rules for the manufacture of spiral and centering drills for metal, include tables of size ranges for different designs and directions of rotation of the spiral. Each standard size has a unique digital code designation. For example, if the diameter of a drill with a cylindrical shank is 3.1 mm, it has an N1 design and a right-handed spiral, then its total length should be 65 mm, the length of the working part should be 36 mm, and the code designation of such a product will be 2300-7517. Size charts for metal drills with a tapered shank include a diameter range from 5 to 80 mm, and for tools with a cylindrical shank - from 0.25 to 20 mm. At the same time, for thin drills with a diameter of up to 1 mm, only version N1 with a right-hand spiral is provided.

Manufacturing materials and coatings

The main materials for the manufacture of working parts of monolithic drilling tools are high-speed steels and hard alloys. Steels with tungsten or tungsten-molybdenum alloys are most often used as high-speed cutters. The latter are also used in a version with the addition of cobalt. Hard alloys, which are produced by powder metallurgy methods, are more durable, stronger and heat-resistant than high-speed steels. They usually contain several refractory metals such as tungsten, titanium, cobalt and tantalum. Some products designed to perform several technological operations in one tool installation (for example, a combination drill) may include components made from different tool materials.

To improve the performance of metal drills, their surfaces are subjected to additional processing or coated with hard metal compounds. The most common processing methods that increase the strength and wear resistance of tools are cyanidation and sulfidation. And for protective coatings Titanium carbonitride (TiCN), including alloyed aluminum (TiAlN), is usually used.

How to choose a drill for the metal being processed

When choosing a drill for metal work, first of all you need to familiarize yourself with the color markings of the ISO 513 standard, which all manufacturers of drilling tools adhere to. It should be understood that such markings are not applied to the product itself, but are present only in its catalog description. You can, of course, rely on the advice of a consultant in a tool store, but this method is only suitable if you need to select a drill bit for a drill designed to work with ordinary structural steel. If you have to drill hard or tough metals or require high-quality custom work, then it is better to follow the recommendations of professionals. The figure below shows an example of the use of color coding from the Mitsubishi catalog.

It must also be remembered that the parameters of the drilling process depend both on the characteristics of the drill and on the power and rotation speed of the drive. Therefore, it is better not to use drill bits for a screwdriver with a drill, as this will most likely lead to their damage. And the rotation speed of the screwdriver is clearly not enough for drilling metal with conventional drill bits.

Drills used in machine tools

On drilling machines in which the spindle mounting hole is made under a Morse taper, drills for metal processing are installed directly into the spindle. And to fix them, it has a special through groove for wedging the foot. The same drills are also used in universal machines (drilling and milling, etc.), in which the spindle mounting hole is made for a metric cone or one of its modern varieties. Only in this case are they inserted into transition mandrels with the appropriate cone. In general, metal drills used on machine tools do not differ from those used when drilling with hand tools. The only type of drilling tool intended only for machine tool use is a drill with a through channel designed to supply coolant to the processing zone (see figure below).

The best manufacturers

Among Russian manufacturers of drilling tools for metal work, the products of the Volzhsky Tool Plant (VIZ), Tomsk Tool Plant (TIZ) and Tulamash Production Association have a good price-quality ratio. The tools of the Ukrainian Zaporozhye Tool Plant (ZIZ) fall into this category. The best quality drills are worldwide famous manufacturers cutting tools, such as German Bosch, Hasser and Ruko, Swedish Sandvik, Japanese Mitsubishi, Taiwanese Winstar, etc. But their products have a fairly high price and are intended mainly for professional use. In addition, metal drills under the trademarks of well-known sellers and manufacturers of power tools are widely available on the market. Basically, this is an inexpensive tool, but many products are of very high quality. In this category, users most often note Zubr, Interskol, DeWalt, Hilti, Makita and Metabo.

Rules for storing drills

At workplaces industrial enterprises Drills are stored in tool cabinets and bedside tables made of sheet metal, installed in the immediate vicinity of the machine, as well as on racks in special tool storage rooms. Drilling tools must be placed in a certain order (by type and diameter) in the appropriate compartments, cases or cases. Laying should ensure the safety of cutting edges, as well as working and seating surfaces. Before storing the drilling tool, clean it of metal dust and contaminants, and if not used for a long time, lubricate it with lithol or technical petroleum jelly. In order to prevent corrosion, it is prohibited to place acid-containing or other aggressive liquids near the tool storage areas. In home workshops, tools should be stored in compliance with the same rules. Only instead of bedside tables and cabinets, it is much more convenient to use plastic pencil cases and special stands (see video below).

When drilling deep holes in metal, it is recommended to pour a small amount of oil on the surface of the tool. I-20 is usually used in production, but not everyone has the opportunity to purchase this particular brand. What kind of oil can be used at home instead of industrial oil? Please share your thoughts and recommendations on this issue in the comments.

Drills- a very popular tool not only in various fields of activity, but also in everyday life, in daily use. Very wide range of drills different manufacturers sometimes they just confuse the average buyer. Let's find out how to choose a drill for metal and which manufacturer's drills should be preferred.

Metal drills

Metal drills are used to cut holes in unalloyed and alloyed steel, cast iron, non-ferrous metal, etc. This type of drill bits has a spiral shape, hence the corresponding name - twist drills. Twist drills have two longitudinal flutes that guide chips away during drilling. There are several types of twist drill shanks - conical, hexagonal and cylindrical. Conical ones are inserted directly into the machine, cylindrical ones into a special chuck.

If you are interested in the question: “Which metal drills are better?”, when choosing a drill, pay attention to the color, it will say a lot about the quality.

Choosing a quality drill by color

If the drill is black, it means superheated steam was used during finishing. This drill has increased wear resistance.

If tempering was used during finishing to relieve internal stresses, the drill will have a faint golden tint.

High-quality metal drills have a bright golden hue - a layer of titanium nitride is applied to the drill. These are very high quality tools, have high strength and reduced friction. A little more expensive than the others, but also higher in quality than the others.

A regular gray drill (the cheapest) does not have any processing. Minimum price and the same service life, and nothing more.

Look at the photo of metal drills to finally remember the types of colors and their inherent characteristics.

Marking drills for metal

The marking depends on the diameter. Drills up to 2mm are not marked; drills up to 3mm are marked with steel grade and diameter; thicker drills may carry information about the manufacturer and accuracy class.

The drill marking begins with the letter P - high-speed steel. The content of various substances in the alloy is also indicated in the form of a numerical value. For example, K6 is part of cobalt, M3 is molybdenum content. On imported drills, the marking is in the form of HSS or Din values.

Having learned the characteristics and types of drills, you now know exactly how to choose a drill for metal. We will only give examples of high-quality drills that are widely used by professionals.

RUKO twist drills for metal TL 3000 (HSS-G, HSS-E, HSS-G TiN, HSS-G TiAlN)

Metal drills ruko model range TL 3000 is known to consumers as a high-quality material at an affordable price. The diameter of the drills is from 3 mm (they have a cross sharpening according to the DIN 1412 C standard). The drills have a sharpening angle of 130°. Depending on the specific model, they have coatings of titanium nitride, titanium aluminum nitride, etc.

Multi-purpose drill bits, great for deep drilling depths. Best suited for materials that produce long to medium chips.

HSS-G drills are excellent at drilling carbon and alloy steels, cast iron, copper and aluminum alloys.

In addition to carbon and alloy steel, HSS-E drills into stainless and acid-resistant steel, as well as copper and aluminum alloy.

HSS-G TiN and HSS-G TiAlN are suitable for all materials described above, as well as titanium alloy.

Metal drills BOSCH HSS-CO

BOSCH drills of the HSS-CO model range are made of high-speed steel according to all standards. The drills have an oxide coating that quickly removes chips while drilling. The standard 135° chisel edge with mesh grinding is suitable for almost any type of work.

Alloying with cobalt improves the strength and heat resistance of the drill. The tensile strength is 1000N/mm2, which allows you to work with most types of steel and alloys, as well as cope with heavy production tasks.

Accuracy class h8 ensures the required outer diameter tolerance.

HAISSER metal drills with titanium coating

One of the most powerful drills that are used under extreme loads in household and industrial conditions. The drills have a cross-shaped sharpening. The titanium coating provides maximum cooling, allowing you to work in the toughest conditions. The main use of drills is in the field of industrial and complex work. Angle 135 with mesh grinding. Titanium nitride coating provides minimal friction and reduced cold welding. Thanks to their high wear resistance, the drills have a uniquely long service life.

Metal drill BISON "Cobalt"

The ZUBR metal drill is made of high-speed steel R6M5K5. Has a cylindrical shank. In terms of strength class it belongs to category A1. The use of cobalt (5%) in manufacturing gives this drill additional strength and wear resistance.

Cobalt drills are used for drilling non-ferrous metals, stainless steel, difficult-to-cut tough steel, etc. Drills are made in accordance with GOST 10902-77. The price of BISON drills “Cobalt” is quite consistent with the quality of the product, which is why many buyers choose this product.

This type of tool, such as a metal drill, can be found in any home craftsman, but it is imperative to have a set of drills of various sizes in order to be able to make holes of the required diameter.

Workshops processing metal at professional level have in their inventory several types of this instrument, differing in type, length and diameter. In addition, they differ in:

type of shanks - an element with which the tool is fixed in the equipment,
type of cutting part - the working surface that cuts metal,
type of working surface - the part of the drill responsible for removing chips from the processing zone.

Cylindrical Twist Drills

This is the most common type of this tool that can be found in the inventory of every master. Can be used in all types of drilling equipment and tools. They are made, according to GOST 885-77, from tool steel of such grades as HSS, P6M5 and P18, which ensures their reliability and durability.

This type of drill has a diameter of 1-16 mm, but in some cases up to 80 mm (as a rule, they are made to special order for workshops and workshops) and is designed to perform almost all types of metal drilling work.

Diameters of metal drills of this type

The table shows standard sizes drills of this type for metalworking. It shows all the options for diameter, length and length of the working part.

Other size options are rare; as a rule, they are produced in small quantities or to order from metalworking enterprises.

Conical drills for metal, their sizes and characteristics

This type of tool has a canonical shank, which is used in machine tools and some types of professional drilling tools and is designed for drilling large diameter holes. Therefore, it can extremely rarely be in the arsenal of a home master.

What diameter are conical drills? The diameter of this type of drill can be 6–30 mm and have increased or normal accuracy. For industrial machines, this tool can have a diameter of up to 75 mm. Below is full table with all sizes.

Core drills for metal, diameters and characteristics

This type of tool is also called cutters because it looks completely different from a classic metal drill. Thanks to this equipment, you can get holes large size– the diameter of which can be 12–150 mm, but a relatively small depth of 5–50 mm. This is due to the structure of the instrument itself.

The equipment is made of high-speed steel. Some drills are tipped with high-strength steel, which significantly speeds up the processing process, 4–12 times less than with conventional drills.

Marking drills for metal, decoding symbols

All metal drills, according to GOST requirements, must have markings that indicate the grade of steel from which the equipment is made.

If there is no such marking, most likely this drill meets the quality requirements and is not recommended for use in professional metalworking. However, for a home handyman it may be excellent option because it costs less.

Let's look at the markings that can be seen on the drill itself; it consists of letters and numbers, for example P 9, P18, P6m5, P9K15. Letter R here means that this tool is made of high-speed steel. Next comes a number indicating the amount of tungsten in the steel. The following is the designation of the alloying substance in the alloy, example:

K6 – the alloy contains six parts of cobalt.
M4 – four parts of molybdenum are present.
F3 – three parts of vanadium.

These elements increase strength, heat resistance and other characteristics.

Marking that comes with the accompanying documents (packaging) for the equipment. Equipment accuracy designation:

A1– increased accuracy.

B1– normal accuracy.

Example 2300-7055 A1 GOST 885-77, where 2300 is the operational and design characteristics, 7055 is the manufacturing serial number (series), A1 is increased accuracy of the tool, GOST 885-77 is the tool meets the requirements of standards 886-77.

Drill markings hss and din

H.S.S.. This marking is used on foreign-made tools used in professional metalworking and capable of processing material with a strength of up to 1100N/mm2. After the abbreviation there are additional letters indicating what metal is added to the alloy, examples:

HSS-G TiN (addition of titanium nitride),
HSS-G TiAlN (with titanium-aluminum-nitride coating),
HSS-Co (addition of cobalt),
HSS-E (cobalt addition),
HSS-G (addition of metal P4M3 – molybdenum),
HSS-R (addition of metal P2M1 – molybdenum),
HSS-E VAP (stainless steel processing equipment).

DIN. Drills with this marking are intended for processing metal with soft and medium chips. They are multi-purpose and are more often used by home craftsmen than by professional workshops.

A metal drill is one of the most popular tools of a mechanic. At the same time, not every master has sufficient experience to choose the right tool. Let's focus on the main parameters for choosing this tool and consider the design features of various drills.

The stores offer both single drills and entire sets - let’s look at when it would be convenient to buy a set, and when it is not necessary. Let's learn to distinguish low-quality drills from good ones.

A metal drill has a special design for cutting this particular material, but can also be used for cutting wood and plastic.

It consists of the following elements:

Cutting - the part of the drill that cuts deep into the metal, the front element
Shank - the back part of the drill, used to secure the tool in the drill chuck
The working element is the surface of the drill that scoops chips out of the hole.

Depending on the specifics of their design, metal drills are:

flat;
spiral;
crowned;
conical

Flat

Drills with a narrow working part. Compared to other drills:

much less likely to warp
simple design
low price

Feather drill for metal with replaceable inserts

cannot be used for drilling wide holes
chips are not removed from the hole. may remain inside, so the holes need to be cleaned and the drill itself must be kept clean

Spiral

The most common type of drill, optimal for creating holes in metal. It is a metal rod with side grooves covering the entire length of the tool. It is these lateral spiral grooves that determine the main property of the drill - removal of chips from the holes.

According to their purpose, twist drills are divided into several subgroups:

Cylinder-shaped drills, general purpose work (industrial and home use). Their diameter reaches 82 mm.
Left-handed twist drills are so called because they have the opposite direction of twisting of the spiral groove, that is, to the left. Thanks to this, the drill can be used to unscrew broken bolts or other damaged fasteners. The fastener is drilled and unscrewed along with the movement of the drill.
High precision drills. These tools demonstrate the highest level of material processing with an accuracy of up to a millimeter.

Crowns

Designed for drilling large diameter holes. They are a large metal glass with teeth on the edge. In some cases, instead of teeth, various coatings of metals or diamonds can be used. To work with high forces, crowns are made of hard alloys.

Drilling occurs only from the outside, so the middle of the hole simply remains empty.

Cone drills

The working surface of drills of this type is smooth and consists of steps. Used to make holes in thin materials. Thanks to their shape, they are easily centered at the first moments of drilling, which, of course, is more convenient than with cylindrical drills. Another undoubted advantage is that with one drill you can produce holes of different diameters; this is easily adjusted by the depth of immersion of the drill into the material. We drilled one diameter to the first step, went deeper one step and increased the diameter.

With such drills you can not only create a new hole, but also expand an existing one.

Manufactured from high-speed steel or HSS. At the same time, they are additionally alloyed with cobalt. It is this that creates the necessary strength for the drill, resistance to fracture and temperature loads. Cobalt drills cope not only with materials of increased hardness, but also with viscous materials. Of course, the high properties of cobalt drills require more significant costs from the buyer, but in our opinion, these costs are completely justified. The performance of one cobalt drill is high enough to replace several non-alloy steel drills.

The hardness of cobalt drills is high enough to drill materials without punching the workpiece before starting work.

Carbide drills

The cutting surface of this type of drill is reinforced with special carbide inserts, while the base of the tool is made of CS. The plates are made from carbide alloys, which have increased hardness and wear resistance. Drill blades are sharpened only once during production and cannot be re-sharpened. Such drills are used for working with particularly hard alloys and metals or for thick metal workpieces.

How to choose drills

To choose the right drill for metal, you need to know not only the final task you are working on, but also understand what characteristics the material that needs to be drilled has. Here are some good questions to answer when choosing a metal drill:

drill material color;
level of sharpening and symmetry of the sides of the drill;
diameter;
how well the shape of the drill matches the standard characteristics;
properties of the material from which the drill is made
purpose of the tool and its capabilities
drill manufacturer
characteristics of working equipment for drilling

For example, for large-diameter holes in metal, powerful drills with low speeds are used.

Now let's look at each drill quality indicator in order.

The color of the surface of a metal drill is a parameter by which one can judge the quality of the presented tool, but, perhaps, this is one of the most dubious ways to determine the quality of the tool. A snag in gray and black drills.

Drills with predominant gray color

There is a point of view that gray drills are the cheapest and unsuitable even for one-time work. Without any improvements or special processing. This is not true. For example, drills that have undergone oxide treatment may well be gray. Therefore, when choosing a drill, do not believe the stories and do not run past the gray drills - they may be quite suitable for the job.

Black color predominates

There is an opinion that black drills are better than gray ones. And more expensive. This is not true or accurate. Yes, there are drills that turn black from steaming or something else, but in general, black drills can also be of poor quality. Do not blindly trust such schemes.

Golden shade of the drill

These are instruments that have undergone a tempering procedure. Tempering the metal means heating it just below the maximum permissible value, and then gradually cooling it in air to a temperature environment. Tempering allows you to relieve the internal stresses of the drill material and improve its strength.

Rich gold color

These drills are considered the best high-end tools, and of course, they are expensive. Actually, the shade of the drill is obtained by adding titanium to the composition. This material reduces the friction of the drill on the surface, which greatly increases its survivability.

When choosing a drill of one type or another, keep in mind how long you expect it to last and what quality of holes you expect.

The more often and more intensely you drill into metal, the more expensive drills will be suitable for the job. As we have already said, it is better to buy one expensive drill than to use 10 of the cheapest ones for professional work. There will be little pleasure from the work; the drilling itself will take more time and effort.

Purchasing cheap tools saves money, but they have to be changed more often, and they are more suitable for one-time or infrequent work with medium force and malleable metal.

Drill sizes

Drills are produced in a fairly wide range of sizes, so to understand this we offer the following classification.

So, drills are:

short: with a length from 18 to 130 mm with a diameter of 0.4-20 mm.

elongated, their diameter is also in the range of 0.3–20 mm, and their length is 19–205 mm;

long, with a length of 56–254 mm and a diameter of 1–20 mm.

Drill markings:

These are symbols containing all the necessary information about a specific instrument. They are not applied to all products.

For example, on small drills up to 2 mm, special marks are not applied.

For drills with a diameter of up to 3 mm, indicate the type of steel used and the cross-sectional size of the tool.

And for tools larger than 3 mm, information is added not only about the grade used in the production of steel, but also the diameter, as well as the manufacturer’s logo.

In addition, digital and letter designation on drills you can determine whether the material contains additional substances, such as cobalt (K), titanium, molybdenum (M).

If the marking contains the letter “P”, then the drill is made of high-speed steel. The international designation is HSS (high speed steel).

Markings are located on the drill shank.

A number of manufacturers provide even more detailed information in the labeling, for example:

country of origin;
company trademark;
grade of steel or alloy;
drill diameter;
what accuracy class does the drill have?
mini-recommendations on the materials used for this drill

However, on drills manufactured abroad, the markings differ from GOST, and in general they are carried out in the Latin alphabet. Let's look at what designations such companies leave.

What does HSS-R and HSS-G mean?

products made of carbon and alloy steels with a strength of no more than 900 N/mm2;

blanks made of metal alloys containing aluminum, graphite, copper, nickel, zinc (bronze, brass, cupronickel, etc.);

gray and malleable cast iron;

HSS-G Co 5

This designation refers to drills that can work with metals with a strength of up to 1100 N/mm2. Such metals, in particular, can be the following steels:

carbon;
stainless;
thermally improved;
acid-, heat- and heat-resistant;
alloyed.

HSS-G TiAN/TiN

If such a designation is present on metal drills, this means that titanium-aluminum-nitride coating is applied to their working part. This coating significantly increases the resistance of drills not only to corrosion, but also to wear, which helps to increase their service life. Tools with this marking can also be used for processing metals and alloys with strength reaching up to 1100 N/mm2. Manufacturers recommend using the following types of drills for processing:

malleable and gray cast iron, in the structure of which graphite inclusions are spherical;
copper-based alloys (brass, bronze, cupronickel);
steel blanks produced by casting (including injection molding).

Manufacturers

Another detail thanks to which you can choose a drill is the company name. There are quite a few of them on the market, but we would like to focus only on the three most interesting from our point of view. Bosch is a manufacturer with excellent equipment, great experts in the industry.

Unlike other tools of the brand, it is the equipment of Praktika that is analyzed in detail. Each group of drills from this manufacturer has detailed descriptions and recommendations for their use. If you are not familiar with drills, then the “Practice” instructions will greatly help with this.

VIRA may not be the most well-known brand of equipment, but it is worth paying attention to. In the drill category, VIRA represents several levels of quality and value.

Characteristics of drills from the RAGE line:

High quality M2 steel
Hardness 63-65HRC
For professional use
The drill is made in accordance with high European DIN standards, number 338.

VIRA HSS-TiN drill series

These are tools made of high-carbon high-speed steel with titanium-nitride coating. The coating not only reduces drill friction, but also protects it from overheating and improves chip removal.

The drill is suitable for effective work with alloy and non-alloy steel, cast iron, plexiglass, cupronickel, copper, bronze.

To perform more simple tasks,VIRA presents. One set allows you to work with wood, metal and stone.

VIRA universal drill set.

made of high quality CS
the set includes 9 drills: for metal (4.6.8 mm.), stone (4.6.8 mm.) and wood (4.6.8 mm.)

Not only specialists, but also home craftsmen often have to process various metal products. And here you cannot do without special tools, in particular drills. And here the question arises about which metal drills are the best and how to choose them correctly.

Design and functional features

Eat different types metal drills, which differ from each other in functionality and design. Moreover, with the help of such devices it is possible to process not only the metal itself, but also other materials, for example:

tree;
ceramics;
polymer materials;
concrete;
brick.

Design features must be taken into account material characteristics, which will be processed. When it comes to metal drills, they include such elements as:

cutting part - performs key work;
shank - with its help the tool is fixed in the equipment chuck;
working surface - it is used to remove chips from the processing area.

Classification

Depending on the design of the drill for metal products there are:

spiral;
conical;
crowned;
flat.

Flat tools differ in the flat shape of the working part, they are also called feather ones. Their advantages are:

lack of sensitivity to distortions;
simple design;
affordable price.

However, they also have their disadvantages:

They cannot be used to drill large diameter holes.
There is no automatic removal of chips from the processed area.

Spiral tools

Twist type drills are the most common. This tool has the shape cylindrical rod, the assembly of which contains spiral grooves, covering its entire working part. Thanks to them, chips are removed from the working area.

Depending on the design and scope of use, spiral instruments are divided into:

Cylindrical - have a general purpose. The diameter of the tools can reach 80 mm; they can be used for both home and industrial purposes.
Left-handed - have a limited scope of use. They are needed primarily when you need to drill a bolt with a broken head or a fastener from a threaded hole that cannot be unscrewed in any other way.
Tools of increased precision - they can be identified by the presence of the designation, A 1. With their help, you can make holes with the most accurate diameter.

Core and cone drills

Crown tools look like metal glass. On its end working part there are cutting teeth, with which you can make holes with a large diameter. Such teeth can be diamond-coated or made from hard alloys.

Conical products have a stepped and smooth working surface and are used to create holes of small thickness. They are able to provide easy centering of the hole at the beginning of work. Their key advantage is ability to make holes of different diameters.

There are also other types of tools, thanks to which even the most highly durable materials can be processed. These are cobalt or carbide tools.

Cobalt tools made of high-speed steel, which has been alloyed with cobalt. This material gives high strength to the drill, thanks to which it is resistant to thermal or mechanical stress and deformation. They can be used to drill even high-strength and tough metals or alloys. The only drawback is the high price, which is compensated by technical characteristics.

If we talk about carbide structures, they differ in that they place on their cutting part carbide inserts, and the main part is made on the basis of tool steel. The plates are made on the basis of carbide alloys, which have high wear resistance and hardness. The cutting plates will not need to be sharpened in the future, and with the help of such a tool you can drill particularly hard metals or alloys, as well as products with great thickness.

When choosing one option or another, you should know in advance where you will use it, and also take into account the characteristics of the material being processed. When purchasing, consider the following tool parameters:

quality of sharpening and symmetry of structural elements;
color;
functional features;
material characteristics;
working diameter;
compliance of the form with standard parameters.

When purchasing a metal drill, you need to take into account the features of the equipment with which it will work. For example, if you need to drill a large hole in a metal product, you need to take a powerful low-speed drill.

Surface color characteristics

The quality of products largely depends on the color of the surface. What does this or that color mean?

Gray - such a tool is inexpensive and is not of the best quality. It has not undergone any additional treatment to help increase its hardness and resistance to burning or deformation. When drilling hard metals, such a drill may not be enough even for one hole.
Black - the tool was treated with superheated steam, has increased strength and wear resistance. The cost is higher than the previous option, affordable for most buyers.
Light golden - after manufacturing, the tool was subjected to a tempering procedure, during which residual stresses inside were eliminated and strength characteristics were improved.
Bright golden - these instruments are the best, they contain titanium. During operation, the level of friction is reduced, thanks to which the service life is long. The disadvantage is the high cost.

When purchasing a drill of a particular shade, think about how often you will use it, and also take into account requirements for quality and accuracy of work.

So, if you plan to use them frequently and intensively for high-quality and precise work, then it is better to purchase bright golden models.

But if you buy cheaper options for this, you will have to change them often, and in the end you will not save anything.

Dimensions

Manufacturers of these tools produce them in a wide range of working sizes. But to make it easier to understand them, you need to be able to distinguish them by series:

short series (length ranges from 20 to 131 mm, and diameter from 0.3 to 20 mm, respectively);
elongated (length 19-205 mm, diameter 0.3-20 mm);
long (length 56-254 mm, diameter 1-20 mm).

Marking

Its labeling, which is not so difficult to understand, will also help you choose a particular product. Depending on the working diameter, it contains the following information:

If the instrument has a diameter of up to 2 mm, there is no marking.
For models with a diameter of 2-3 mm, it includes information about the steel grade and cross-sectional size.
If the diameter is more than 3 mm, then the marking includes data on the steel grade, working diameter and an imprint of the manufacturer’s logo.

This or that alphanumeric designation of the material grade indicates not only the category of the alloy, but also about the presence of additional components in it.

For example, the letter “P” means that the product is made from high-speed steel. If there is a letter “M”, then this indicates that the composition contains molybdenum, and “K” indicates the presence of cobalt. These additional substances are designed to improve the performance of the product.

Foreign manufacturers include in their labeling more information, in particular the markings in them indicate the following:

country of origin;
trademark;
alloy grade;
working diameter;
accuracy class;
brief recommendations on materials that can be worked with with this tool.

Features of foreign markings

So, if we talk about the last point, which indicates the presence of recommendations on what materials are best processed with one or another tool, then such markings on foreign models are deciphered as follows:

HSS-R and HSS-G - the product is recommended for processing steel products made by simple casting or injection molding, and those made on the basis of alloy or carbon steels with a strength of up to 900 N/mm 2, things based on metal alloys ( containing copper, zinc, nickel, aluminum, etc.) billets based on malleable or gray cast iron.
HSS-G Co 5 - recommended for drilling metals with a strength of up to 1100 N/mm 2. These include stainless, carbon, alloy, thermally enhanced and heat, acid or heat resistant types.
HSS-G TiAN/TiN - the working part of such products is coated with titanium, aluminum and nitride. This increases their resistance to wear and corrosion, and the tools themselves can be used for processing metals with a strength of up to 1100 N/mm 2. This includes malleable and gray cast iron, copper alloys, and steel blanks made by casting.

Which metal drills are better?

After reviewing the markings and characteristics of metal drills, let's move on to popular brands that are present on the market. It is no secret that the service life and quality of work largely depend not only on the characteristics of the product, but also on the manufacturing company.

Experts advise paying attention to the following brands:

Brands from the CIS countries are highly durable and reliable, resistant to wear and have an affordable price compared to foreign analogues.
Ruko - products can have a cross sharpening and different types spraying, they can be called the best example of the relationship between price and quality of products.
Bosch - this brand speaks for itself.
Haisser - the products of this brand have their own design features, special alloys are used for its manufacture. All this allows it to be successfully used even under extreme loads.
"Zubr" is a Russian brand that offers high-quality and reliable options at an affordable price.

Rules for sharpening

If the cutting part of the drill is dull, then it needs to be sharpened. Follow these recommendations:

Check whether the sharpening device is working properly and prepare a container with coolant.
When sharpening, press the tool tightly against the grinding wheel, starting processing from the back of the cutting edge.
The processing angle depends on the material of manufacture. For steel it is 140 degrees, for copper - 100, and for copper alloys - 120 degrees, respectively.
As a result of the work, the entire cutting surface, including the side, must be processed.

Since there are so many different drills on the market for processing metal products, sometimes right choice and it can be extremely difficult to avoid mistakes in your work. This material will allow you to choose the right tool option.

THE BELL