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.). It is quite difficult to determine all the necessary characteristics of a drill by appearance, 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.
Drill design and geometry
Any drill, regardless of its purpose and design features, consists of two main components: the shank and the working part. The first serves to transfer 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 directs 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 must 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.
Metal drills: varieties of diameters depending on the shape and task
The need to make a hole in a metal product arises not only among builders or metal craftsmen. Quite often, such a need may arise at home. But to make a hole you will need suitable tools and drills of the required diameter.
At the same time, the question arises: what types of metal drills exist? Surely each type has its own advantages and disadvantages. The answers to this and many other questions are in this article.
Selection Criteria
Choosing a drill for metal is a very important step. After all, the quality of work largely depends on this product. By purchasing a low-quality model or a drill of the wrong diameter , you can not only ruin your mood, but also damage the metal product in which you needed to make a hole.
Therefore, when choosing, you should rely on the following characteristics:
- Required diameter.
- Symmetrical sharpening.
- Hardness and strength of the product.
- The type of metal from which the drill is made.
- Manufacturer.
- And, of course, the price.
In order not to make a mistake with the choice, experts recommend purchasing such devices in a set. Usually in one package there are 6-8 drills of different diameters. However, products can be purchased individually. True, this will require certain knowledge.
Variety of shapes and diameters
A standard drill has a cylindrical shape and consists of a cutting part and a shank. At the same time, each product has special recesses (so-called working surfaces) that remove chips from the hole. Based on these parameters, a wide variety of products are distinguished, each of which has its own diameter ranges:
- Screw model with tapered shank . Most often, such modifications can be found on special two-handed drills or drilling machines. In this case, the drill is mounted on a conical shank, and not on a chuck, as usual. Such products are used for drilling large holes, and therefore have a wide diameter.
- Crown varieties . The cutting part of such models is much wider than the shank, so it is shaped like a crown. As a rule, such modifications are used to drill holes in several metal sheets. Therefore, there are frequent teeth on the working surface.
- Products with a stepped shape . They appeared relatively recently, so they have a less wide selection of products. Nevertheless, they are gaining popularity by leaps and bounds due to their versatility. The fact is that with the same drill you can make holes with a width of 4 to 36 mm. Accordingly, the more “steps”, the higher the cost. However, this innovation can only be used on sheet metal.
- Left-hand modifications . It is quite difficult to find this variety in a store due to the specificity of its application. The purpose of such devices is to remove a broken screw or bolt. Based on this, there are only 5–7 varieties in diameter.
- Carbide models . They are distinguished by a one-sided sharpening angle and high strength. These qualities allow the products to be used for working with strong metal. Most often, such drills are produced with a small radius, but you can always make an individual order.
- High precision products . As the name implies, such devices are designed for high-precision work, so the size error is minimized. Because of this, high-precision drills are significantly higher in cost than standard models. As a rule, they are used in special enterprises, and not at home.
- Threaded _ They are used only in cases where it is necessary to make a thread in the hole. However, despite their narrow specialization, they have a huge variety in diameter.
Diameter and marking
The presence and volume of information on the drill depends on the size of the product. That is, the larger the diameter, the more data is indicated. Typically, manufacturers adhere to the following sizes:
- Drills with a cross-section of up to 2 mm are not marked.
- Products with a diameter of 2 to 3 mm contain information about the steel grade and cross-section.
- On models from 3 mm, data on the manufacturer, cross-section and alloy composition are entered.
However, this applies only to domestic producers. Foreign companies try to provide as much information as possible about the product . This especially applies to large brands, which usually indicate:
- The country in which the drill was made.
- Company `s logo.
- Composition (usually the grade of alloy or steel).
- Product size and cross-section.
- Accuracy class.
- And even brief recommendations for use (for which metal a particular drill is best suited).
To decipher the markings you do not need any specific skills. The manufacturer made sure that everything was intuitive. For example, the letter “P” is used to mark high-speed steel, and numbers with letters indicate the proportions of a particular element. For example, the larger the number next to the letter (for example, K - cobalt), the higher the concentration of this element.
In conclusion
In the modern world there are many products designed to work with metal. However, if you need to make a hole in a metal object, then nothing will cope with this task better than a special drill. Nevertheless, it is very important to choose a product of a suitable diameter, since the outcome of the work largely depends on this parameter.
Using low-quality products can harm both the metal object and yourself. Therefore, you should purchase products from well-known brands that not only produce high-quality drills, but also provide a wide variety of models.
- Vitaly Danilovich Orlov
Types of drills for metal
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 design, modern step drills, as a rule, are 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.
We drill different materials with different drills
We work on metal
1. If you need to make holes in non-ferrous metal, cast iron, steel, use spiral-type drills. The longitudinal grooves machined into them carry away the chips generated during operation. It should be noted that metal drills differ from each other not only in material and coating, but also in the type of shank. It can be made in the form of a cone, cylinder or hexagon. To attach cylindrical drills, you need a chuck; conical drills are inserted more easily - directly into the machine.
The quality of a drill can be determined by eye - to do this, take a closer look at its color. Thus, ordinary drills of low quality have an inconspicuous gray color.
But the black drill is more durable - this means that it was treated with superheated steam at the end of production.
The tool has a light shade of gold that has been treated with tempering, relieving internal tension.
And if the drill shines brightly with gold, it means it is coated with titanium nitride. Such a drill will serve faithfully for a long time, and its friction is reduced due to the coating. Although its price is higher than that of other types of drills, the quality more than pays for it.
2. Carbide drills. Since metals have different densities, different drills must be used to process them. Hard materials such as heat-resistant steel, cast iron or non-ferrous metal require the use of tools made of carbide.
3. A few words should be said about step-type drills, which appeared not so long ago. They are very convenient for drilling fairly thin sheets of plastic, tin, and roofing materials. The holes can be from 0.4 to 3.6 centimeters or even more.
Working with wood
If you need to make small holes (no more than 1.2 centimeters in diameter) in a chipboard or wooden surface, then a regular spiral drill for metal can handle these. But large holes or those that require increased precision are drilled only with a special tool designed for working with wooden surfaces. They are made from special tool steel, carbon or alloy. They are not suitable for metal.
The following wood drills are available:
1. Twist type drill bit is suitable for small and medium holes. Instead, you can take a metal drill, but the hole will turn out to be of slightly worse quality.
2. Screw drill. A single-spiral drill with a sharp cutting edge is also called a twisted drill. Due to its screw-like shape, excess chips are easily removed from it during operation. If you need to get a deep hole with smooth edges, you can't do without a screw drill.
Above is a spiral drill, below is a twisted drill bit for concrete.
3. The feather type drill is suitable for making holes with a diameter ranging from a centimeter to 2.5 centimeters. The result will not be of very high quality - rough walls, approximate accuracy. But these drills can please you with an extremely low price.
4. Crowns for wood. A drill made in the form of a crown (ring) can be used when you have to drill a hole with a diameter of up to 10 centimeters. As a rule, the set contains one shank, a mandrel and a center drill. Several crowns are included in the kit.
5. The Forsner drill has a centering point and a sharp-edged scoring tool. Thanks to it, the cutting line is accurate. For blind holes that have clear dimensions, this tool is perfect. They drill into soft wood, laminate and chipboard.
We work on concrete and brick
To comfortably work with surfaces such as brick, stone and concrete, you must have a drill with a hard tip. It is made of a special alloy, and drilling is carried out using shock-rotational movements.
Unlike conventional drills with a cylindrical shank, the drill used in a hammer drill can have a different shape in addition to the cylindrical one. These are, for example, SDS-top, SDS-max or SDS-plus. Drills with SDS shanks are used to work with rotary hammers.
1. If you need to make a medium or small hole in concrete, take a drill or drill with a carbide tip. The shape of the tool is in the form of a screw.
At the top is a concrete drill, below is a concrete drill for a hammer drill.
2. We drill a large hole with a crown, which has carbide teeth on the edge. In this case, we use the percussion drilling method using a hammer drill. You can also use a diamond-coated tool. We use either non-impact drilling with water cooling or dry drilling. The core remains inside the nozzle - a cut out piece of material.
Pobedit drills can have different quality - it depends on the brand of this material (pobedit). To drill a granite surface, you need to take a drill with plates made of medium or high hardness. Medium soft or soft plates are suitable for soft concrete or brick. This must be taken into account when purchasing Pobedit drills and drills.
We work on glass and ceramic tiles
It is more convenient to drill glass and tiles either with a crown or with a tool made in the form of a spear.
1. A spear-shaped drill tip can be either pobedite or made of tungsten carbide. In addition, there are ring-shaped drills with diamond coating. If you don’t have a special tool at hand, you can take a drill for concrete work, only a sharp one. And you have to work carefully - after all, this drill has a different shape.
A spear-shaped drill bit for ceramic tiles, and below that an annular drill bit with diamond coating.
2. But a crown for glass or ceramic tiles looks about the same as a crown for concrete work, but it does not have teeth, but only dusting.
3. The tiles can be drilled with special ballerina drills. They come in handy if you need to make a large hole. Drill carefully, from the inside of the tile, with the drill speed set to minimum.
We drill everything
Perhaps the classification of drills would be incomplete without mentioning universal drills. When finishing rooms, this tool can be used to work on almost all surfaces. Brick and concrete, tiles, wood and plastic, aluminum, steel - a universal drill can handle all of this. It also has a tricky sharpening, which, by the way, is also called universal.
Shank types
In accordance with early Soviet GOSTs, 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 the 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.
What steel are metal drills made of and which is better?
To choose high-quality drills that can last a long time and maintain sharpness despite repeated use, it is important to know what types of steel such a tool is made from and what their differences are. The best metal drills are made from high-speed steel HSS (a common abbreviation) with the addition of a number of impurities. The price of the instrument and the properties described above depend on their type and quantity.
High speed steel is characterized by its high hardness, ability to resist fracture and tolerance of temperature resulting from drilling speed. The material is doped with special impurities, which is indicated in the marking.
For example:
- P - reports that tungsten is present in the alloy.
- F is an indicator of the presence of vanadium.
- M - indicates the addition of molybdenum.
Sometimes manufacturers list the type of steel as a special benefit of their products. What can such a marking tell us? Let's look at popular options.
Drill bits made of HSS-E steel
5-8% cobalt is added to this high-speed steel. This technological solution allows them to drill into stainless steel with a tensile strength of up to 1200 N/mm2. Designed for particularly astringent and difficult materials when heated. Instead of the letter E, they may be designated Co.
HSS-E steel drill
Drills made of steel HSS-TiAIN
They have a three-layer coating (titanium-aluminum-nitride). This increases their heat resistance to a temperature of 900 degrees and allows them to be used on steel with a strength of 1100 N/mm2. They have an increased service life, 5 times longer than other types.
Drill made of HSS-TiAIN steel.
Drills made of HSS-TiN steel
The marking indicates that the outer layer is sprayed with titanium nitride. This adds strength and increases heat resistance up to 600 degrees. Suitable for making holes in cast iron, aluminium, carbon and alloy steel with a tensile strength of 1100 N/mm2.
Drill made of HSS-TiN steel.
Drill bits made of HSS-G steel
Suitable for cast iron and various types of steel with a tensile strength of 900 N/mm2. The cutting part in them is polished using cubic boron nitride. This gives resistance to radial runout and abrasion resistance. Drills made of this steel are the most common.
Drill made of HSS-G steel.
Steel drill bits HSS-R
This is a high-speed steel with the lowest durability. It can also be indicated simply without the letter R, which will mean conventional heat treatment (hardening) and roller rolling. Suitable for creating holes in mild steel and cast iron.
Drill made of HSS-R steel.
Carbide drills
This type of material only touches the tip of the drill. It is designed to withstand very high temperature loads and is abrasion resistant. This HHS is used for drills designed to work with titanium alloys, heat-resistant steels and stainless steel.
Carbide drills.
For long service life and working with particularly hard metals, it is better to choose HSS-E and HSS-TiAIN drills. To drill holes in regular carbon steel and not overpay, HHS-R or slightly better HSS-G is enough.
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 | Certain types of 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 those with a lower index have greater hardness and wear resistance.
Drill manufacturing technology
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.
How to determine what type of work a twist drill is intended for (concrete or metal)
To determine what kind of work a twist drill is intended for (concrete or metal), look at its tip. For instruments of the first category, they have a special shape.
Photo No. 4: twist drills for concrete
As you can see, the diameters of the blunt tips are larger than the diameters of the drills themselves. These elements of the working parts are made from pobedit. This is a super-strong alloy that is used in the production of equipment intended for the extraction of mining materials. It is the pobedite tips that make drilling in concrete possible.
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. The size tables 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.
Drill bit conversion table[edit]
click to see a ruler comparing millimeters to fractions of an inch
See also: Drill and Tap Size Chart
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| 0,406 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 77 | 0,018 | 0,457 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 76 | 0,020 | 0,508 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 75 | 0,021 | 0,533 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 74 | 0,0225 | 0,572 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 73 | 0,024 | 0,610 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 72 | 0,025 | 0,635 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 71 | 0,026 | 0,660 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 70 | 0,028 | 0,711 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 69 | 0,0292 | 0,742 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 68 | 0,031 | 0,787 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 67 | 0,032 | 0,813 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 66 | 0,033 | 0,838 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 65 | 0,035 | 0,889 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 64 | 0,036 | 0,914 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 63 | 0,037 | 0,940 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 62 | 0,038 | 0,965 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 61 years old | 0,039 | 0,991 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 60 | 0,040 | 1.016 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 59 | 0,041 | 1.041 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 58 | 0,042 | 1.067 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 57 | 0,043 | 1.092 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 56 | 0,0465 | 1,181 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 55 | 0,052 | 1,321 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 54 | 0,055 | 1,397 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 53 | 0,0595 | 1,511 |
| 1,613 | ||
| 51 | 0,067 | 1,702 |
| 50 | 0,070 | 1,778 |
| 49 | 0,073 | 1,854 |
| 48 | 0,076 | 1,930 |
| 47 | 0,0785 | 1,994 |
| 46 | 0,081 | 2,057 |
| 45 | 0,082 | 2,083 |
| 44 year | 0,086 | 2,184 |
| 43 years old | 0,089 | 2,261 |
| 42 | 0,0935 | 2.375 |
| 41 years old | 0,096 | 2,438 |
| 40 | 0,098 | 2,489 |
| 39 | 0,0995 | 2,527 |
| 38 | 0,1015 | 2,578 |
| 37 | 0,104 | 2,642 |
| 36 | 0,1065 | 2,705 |
| 35 year | 0,110 | 2,794 |
| 34 | 0,111 | 2,819 |
| 33 | 0,113 | 2,870 |
| 32 | 0,116 | 2,946 |
| 31 year | 0,120 | 3,048 |
| 30 | 0,1285 | 3,264 |
| 29 | 0,136 | 3,454 |
| 28 year | 0,1405 | 3,569 |
| 27 | 0,144 | 3,658 |
| 3,734 | ||
| 25 | 0,1495 | 3,797 |
| 24 | 0,152 | 3,861 |
| 23 | 0,154 | 3,912 |
| 22 | 0,157 | 3,988 |
| 21 years old | 0,159 | 4,039 |
| 20 | 0,161 | 4,089 |
| 19 | 0,166 | 4,216 |
| 18 | 0,1695 | 4,305 |
| 17 | 0,173 | 4,394 |
| 16 | 0,177 | 4,496 |
| 15 | 0,180 | 4,572 |
| 14 | 0,182 | 4,623 |
| 13 | 0,185 | 4,699 |
| 12 | 0,189 | 4,801 |
| 11 | 0,191 | 4,851 |
| 10 | 0,1935 | 4,915 |
| 9 | 0,196 | 4,978 |
| 8 | 0,199 | 5,055 |
| 7 | 0,201 | 5,105 |
| 6 | 0,204 | 5,182 |
| 5 | 0,2055 | 5,220 |
| 4 | 0,209 | 5,309 |
| 3 | 0,213 | 5,410 |
| 2 | 0,221 | 5,613 |
| 1 | 0,228 | 5,791 |
| 5,944 | ||
| B | 0,238 | 6.045 |
| C | 0,242 | 6,147 |
| D | 0,246 | 6,248 |
| E | 0,250 | 6,350 |
| F | 0,257 | 6,528 |
| gram | 0,261 | 6,629 |
| HOUR | 0,266 | 6,756 |
| I | 0,272 | 6,909 |
| J | 0,277 | 7,036 |
| K | 0,281 | 7,137 |
| L | 0,290 | 7,366 |
| M | 0,295 | 7,493 |
| N | 0,302 | 7,671 |
| ABOUT | 0,316 | 8,026 |
| P | 0,323 | 8,204 |
| Q | 0,332 | 8,433 |
| R | 0,339 | 8,611 |
| S | 0,348 | 8,839 |
| T | 0,358 | 9,093 |
| U | 0,368 | 9,347 |
| V | 0,377 | 9 576 |
| W | 0,386 | 9,804 |
| X | 0,397 | 10.08 |
| Y | 0,404 | 10,26 |
| Z | 0,413 | 10,49 |
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).
See also[edit]
- Drill and Tap Size Chart
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The best manufacturers
Among Russian manufacturers of drilling tools for metal work, the products of the Volzhsky Tool Plant (VIZ) and Tomsk Tool Plant have a good price-quality ratio. The tools of the Ukrainian Zaporozhye Tool Plant (ZIZ) belong to this category. The best quality drills are from world-famous manufacturers of 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 are widely available on the market under the trademarks of well-known sellers and manufacturers of power tools. Basically, this is an inexpensive tool, but many products are of very high quality. In this category, users most often refer to Interskol, DeWalt, Hilti, Makita and Metabo.
Rules for storing drills
At workplaces of 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.
