How to drill metal correctly - learn how to make holes of various diameters. Drilling a hole in metal How to drill a hole in metal

Now drilling large diameter holes in metal is not a serious problem.. The main thing is to prepare well. Let's say you need to make a hole in a corner, channel or mortgage to strengthen the building structure or hang a shelf, lamp or pipeline. That is, to carry out this not in the conditions of a workshop or workshop, but directly on the spot. The easiest way to drill in such conditions is to use an electric drill. But, imagine how much pressure you need to apply to it in order to drill a hole with a diameter of 16 or 20 mm? The question is not rhetorical - the effort will be about 40-50 kgf. This is not at all easy to ensure if the intended hole is located above the shoulder level of the driller. Even 10 years ago, when such a task arose, even professionals resorted to autogen and, just imagine, to drilling small holes around the circumference of a large one. Today, there is a completely professional solution for this - core drilling, which ensures the production of holes according to 11 grades.

However, many are sure that core drilling is a rather expensive method, economically viable only with industrial volumes. Is such a statement true? Partly. To date, you can choose from several options for tools and equipment for drilling holes in metal of large diameter without reaming. At the same time, the cost per hole will be justified even when drilling only a few holes.

Consider, what tool options for drilling through holes of large diameter in metal does the market offer. For comparison, we take a diameter of 51 mm.

First, this bimetallic crowns. The choice includes samples from the cheapest ones, which are immediately sold in sets and cannot be accepted by us in this review for the reason that their purpose is to drill wood, and if they manage to drill a sheet of metal, then it will be no thicker than 0.5 mm . At a price of 240 rubles, products with a wall thickness of 1-1.2 mm start, often it is marked HSS -Co 5% and even HSS -Co 8, but judging by the fact that drilling one hole in stainless steel takes more than one such crowns, cobalt is probably not there at all. twice as expensive crowns of more decent quality, really allowing you to drill stainless steel and ordinary steel a few millimeters thick. Bimetal crowns this level allows you to drill 5-20 holes in a steel sheet with a thickness of 5 mm. At the same time, the use of any lubricating-cooling composition ensures that the upper bar of this range is reached. At the third stage there are bimetallic crowns of world-famous brands, which are twice as expensive, can be equipped with special devices for quick change in a drill, but do not exceed the average price level by much or at all.

Drilling holes of large diameter in steel sheets with a thickness of more than 5-6 mm for bi-metal crowns is a great difficulty, although sometimes you can hear a different opinion. It is based on data on the total drilling depth of such crowns - 35-38 mm. As a rule, only sellers of bimetallic crowns, who do not have a more worthy tool in their assortment, risk advising to drill a 30 mm sheet or beam in this way. The fact is that the bimetallic crown is devoid of a chip removal groove, and as soon as the thickness of the drilled metal becomes greater than the height of the tooth of the crown, problems with chip removal begin. In addition, the body of the bimetallic crown is not quite cylindrical, which causes jamming in the metal of solid thickness.

Unlike bimetallic crowns, they provide more accurate drilling. The body of the carbide hole saw is chiselled, while the bi-metal hole saw is rolled from a band and welded into a ring. There are several types of carbide drill bit designs. Without delving into the types of shanks and types of attachment, we will analyze only the cutting part. The most expensive part of the crown is the carbide teeth. The quality of the material greatly affects the drilling speed, impact resistance, bit life and the ability to drill alloyed steels with a high chromium content.

The second feature that you need to pay attention to is the shape of the tooth and its size. For drilling thin sheet steel, thin stainless steel and non-ferrous metals, a narrow tooth with a flat profile, slightly beveled inward, is used. Such crowns also do not have a chip-removing groove, and they will not be able to drill metal thicker than the height of their tooth. The price of such crowns is two to three times higher than that of bimetallic crowns, depending on the design of their body, they can be designed or. Since these are professional samples, fakes are not common at present, and almost all samples found on the market are of acceptable quality, but excellent quality should be chosen from manufacturers specializing in these products.

Thicker metal can be drilled. In such crowns, every second or, as a rule, one of three consecutive carbide teeth is sharpened in its own way. This provides soft cutting, no vibration, reduced load on the cutting edges and, as a result, an increase in the resource of the crown. In such crowns, there is a short or long chip removal groove, almost the entire height of the wall. The first version of the crowns allows you to drill metal up to 12 mm thick, and up to 25 mm. It is this version of the tool for drilling holes in large diameter metal that is the most progressive, providing the best performance and quality. The price of such crowns is 20-30% higher than that of thin-walled ones and in absolute terms is 1880-1910 rubles, as we agreed, for a crown with a diameter of 51 mm. As elsewhere in nature, there are deviations in one direction or another up to 2 times, but, as usual, to consider builds a golden mean.

An option in which the metal is quite thick, say 10 mm, and the hole diameter is 20-25 mm can be solved. It is recommended as a drive, but you can also use an electric drill. With the mentioned machine, investments will amount to 21,164 rubles without VAT, and with a drill - 5,000 - 5,500 thousand.

For a hole with a diameter of 50-60 mm, with such a metal thickness, the use of a magnetic or stationary drilling machine is clearly required. A large load causes a high cost of investing in equipment, and together with a crown it will be about 56,000 rubles, or, alternatively, with magnetic drill stand and a separately purchased drill about 50,000. Drilling such holes with a drill from your hands is not only difficult, but also dangerous.

Drilling large-diameter holes in metal up to 5 mm thick with a hand-held electric drill is not difficult when using both bi-metal and carbide drill bits. The choice of tool is made depending on the required accuracy. When drilling holes with a bimetallic crown, the ovality of the holes and the increase in diameter from the desired one can reach 4% or in absolute terms - 2 - 3 mm. When drilling with a carbide crown - only 0.6 - 1 mm. In addition, all carbide drill bits presented in the review, and almost all metal drill bits available on the market, also drill stainless steel.

Drilling metal with a drill is somewhat more difficult than wood, brick or concrete. There are also some features.

For convenience, we have combined practical advice on this type of work into step-by-step instructions.

1. You will need the following tools: a drill, a drill, coolant (oil is better, but water is also possible), a center punch, a hammer, goggles.
2. When drilling metal on a horizontal surface, we put a wooden block under the product and fix it as best as possible. When working in a vertical position, rigid fixation is extremely important, since drilling must be strictly perpendicular.
3. We make markings, after that, using a center punch and a hammer, we outline the center of the future hole.
4. Pour coolant into a small container.
5. We put on protective goggles.
6. We start drilling. Do not exert strong pressure on the drill, because it is better to work at low speeds. If the drill is powerful, then the method of short-term inclusions is suitable, until the tool has had time to gain maximum speed.
7. Do not forget to cool the drill as often as possible .
8. When drilling is not strictly perpendicular, but at an angle, it is likely that the drill will jam. If this happens, put the switch in the reverse position. So you avoid injury and do not break the drill.
9. If everything was done correctly, then even at home, using a low-power drill, you can drill a hole in metal up to 5 mm thick inclusive and up to 10-12 mm in diameter. More complex tasks will be discussed below.

Metal drilling work

It is possible, but this is in case of emergency for shallow holes with a small diameter. Unprofitable.

It is better to use either standard metal drills with steel grade R6M5 or improved - R6M5K5.

The letter K in the marking indicates that this is an alloy with the addition of cobalt. On the market you can find a drill, which is called "Cobalt". We will not vouch for all manufacturers, we only note that the reviews on practical application in the vast majority of cases are positive.

How to drill with a step drill for metal?

Step drills are universal - just one can make holes of different diameters (from 2 to 40 mm). They are most effective when working with thin metal, when you need to get a neat edge. They are better fixed in the cartridge, they are easier to sharpen, and therefore, with proper operation, they last longer, but they are also more expensive than usual ones. They work with the same principles, but it is easier to drill large diameter holes than with conventional twist drills.

Is it possible to drill metal with a Pobedite drill?

The principle of operation of metal drills is to cut, and crush materials with victorious soldering. Brick, concrete, stone are better suited for this. Therefore, as mentioned above, it is, of course, possible to drill metal with a concrete drill, but it will quickly become unusable and the victorious soldering will collapse.

Turnovers

What is the larger hole diameter? the lower the turnover should be. The more depth? the gradually you need to reduce the pressure on the drill. With a drill diameter of up to 5 mm, the torque should not be higher than 1200-1500 rpm. Accordingly, 10 mm in diameter - no more than 700 rpm, 15 mm - 400 rpm.

How to drill holes in large diameter metal?

As a rule, most drills for domestic use have a power of 500 to 800W, which allows drilling holes up to 10-12 mm in diameter.

How to drill metal with a thickness of more than 10 mm with an electric drill?

In metal up to 2 mm thick, using step drills, holes up to 40 mm can be made. With a thickness of 3 mm, bimetallic crowns are better suited.

Bimetal crown

When drilling deep holes with any tool, you may sometimes need a magnet to extract the chips.

metal drilling process

Particular attention should be paid to safety, be sure to take care of your eyes from chips, and if there is a skew and jamming, immediately turn off the drill and rearrange the torque to reverse.

In a power outage or where the noise of an operating tool may disturb others ( read: when can repairs be made so as not to quarrel with neighbors?) - an ideal solution for drilling metal would be a manual mechanical drill, the so-called brace. Low speed and pressure, no overheating, just what you need. Of course, there are also disadvantages - the cost of time and fatigue. In such a simple "old-fashioned" way, you can drill holes with a diameter of up to 10 mm.

We hope our advice will be useful to you.

More information in this video.

Coolant for metal cutting

Rolled metal drilling: types and technology

The drilling procedure can be safely called one of the most important technologies for processing metal products.

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The main purpose of drilling is to obtain mounting and technical holes of various diameters, depths and shapes, threading, countersinking and reaming. This procedure is carried out on drilling machines of various sizes and configurations. Also, the Center MTS company is engaged in the production of stuffed glands.

With the help of the drilling method carried out on modern equipment and the use of a special tool, various operations are performed, among which the following can be distinguished:

Drilling cylindrical holes

Drilling holes with oval or polyhedral configuration;

Reaming, countersinking and even grinding of existing holes.

The drilling technology implies the possibility of obtaining both blind and through holes in metal structures of various sizes and shapes. At the same time, using special equipment equipped with CNC, it is possible to ensure high hole accuracy, prepare the product, for example, sliding supports for subsequent assembly or further operations prescribed in the technological process.

This method is used to process products or workpieces made of various types of steels and cast iron. Naturally, for each material, a cutting tool (drill, countersink, reamer) is individually selected, as well as processing modes, lubrication and other parameters.

This type of metalworking as drilling is indispensable in various industries, ranging from small enterprises engaged in small-scale production of components for equipment, and large factories that have a full cycle of production of a certain range of products. The accuracy of processing, as well as the characteristics of the holes obtained by drilling, directly depend on the machines, tools and technologies used.

Drills for metal are selected based on the diameters of the holes and the properties of the material being processed. As a rule, they are made of high-speed steels, such as R6M5K5, R6M5, R4M2. Carbide drills are used to work with cast iron, carbon and alloy hardened steels, stainless steel, and other difficult-to-cut materials.

The power of the electric drill must be designed to drill a hole of the required diameter. Power tool manufacturers indicate the relevant technical data on the product. For example, for drills with a power of 500 ... 700 W, the maximum drilling diameter for metal is 10 ... 13 mm.

There are blind, incomplete, and through holes. They can be used to connect parts to each other by means of bolts, studs, pins and rivets. If the hole is drilled for the purpose of threading, you should pay special attention to the choice of drill diameter. Due to its beating in the cartridge, a breakdown of the hole occurs, which must be taken into account. Indicative data are presented in the table.

To reduce breakdown, drilling is performed in two stages: first with a smaller diameter drill, and then with the main one. The same method of sequential reaming is used when it is necessary to make a hole of a large diameter.

How to drill metal with a drill

The peculiarity of drilling metal with a drill is that it is necessary to manually hold the tool, give it the correct position, and also ensure the required cutting speed.

After marking the workpiece, the center of the future hole should be punched. This will prevent the drill from moving away from the set point. For the convenience of work, the workpiece should be clamped in a bench vise or placed on a stand so that it takes a stable position. The drill is set strictly perpendicular to the surface to be drilled. This is important to avoid damage.

When drilling metal, the drill does not need to exert much pressure. On the contrary, it should decrease as you go. This will prevent breakage of the drill and also reduce burr formation on the trailing edge of the through hole. Chip removal should be monitored. If the cutting tool jams, it is released by reverse rotation.

Cutting mode selection

When using a tool made of high speed steel, you can refer to the speed according to the data in the table. When working with carbide drills, the allowable values ​​are 1.5 ... 2 times higher.

Drilling of metal products must be carried out with cooling. If it is not used, there is a high probability that the tool will lose its cutting properties due to overheating. The cleanliness of the surface of the hole in this case will be quite low. An emulsion is usually used as a coolant for hard steels. At home, machine oil is suitable. Cast iron and non-ferrous metals can be drilled without coolant.

Features of deep hole drilling

Holes are considered deep if their size is greater than five drill diameters. The peculiarity of the work here lies in the difficulties associated with cooling and chip removal. The length of the cutting part of the tool must be greater than the depth of the hole. Otherwise, the body of the part will block the helical grooves, through which chips are removed, and liquid is also supplied for cooling and lubrication.

First, the hole is drilled with a rigid short drill to a shallow depth. This operation is necessary to set the direction and centering of the main tool. After that, a hole of the required length is made. As you progress, you need to remove metal shavings from time to time. For this purpose, use coolant, hooks, magnets, or turn the part over.

Drilling metal is one of the most common plumbing operations. Collapsible and non-collapsible connections - rivet, screw, bolt, hairpin - require holes. To drill metal, it is enough to have a drill, a drill of the appropriate diameter and a center punch with a hammer for basting the hole.

Drill selection

If holes in the metal are drilled for threading, then according to GOST 24705-81, for the most commonly used thread sizes (for standard large pitches): M4, M5, M6, M8, M10 and M12 - the diameter of the drills will be 3.3, respectively; 4.2; 5; 6.7; 8.4; 10.2 mm. It is quite acceptable if drilling for threading will be carried out with a drill, the diameter of which differs slightly (by 0.1 mm) from the GOST dimensions in one direction or another.

When purchasing drills, you need to keep in mind that conventional drills made of high-speed tool steel (for example, R6M5) are designed for drilling metals that do not have high hardness. To drill through hard metal, carbide drills are required. These drills can be full carbide or have only a carbide tip.

Sometimes, before starting drilling, it is not known what hardness the metal is to be drilled. Therefore, when you see at the first moment of drilling that the drill does not penetrate into the metal, you must immediately stop drilling, otherwise the drill will be irrevocably disabled, overheating and losing hardness. Evidence of this will be the appearance of a dark blue color on it. Before drilling metal, the hardness of which is not known, you can run a file through it. If the latter does not leave traces on the metal, then the material has increased hardness.

How to drill metal

Optimal for drilling most metals are low and medium speeds - 500-1000 rpm. High speeds quickly heat up the drill, as a result of which its annealing and softening can occur. When drilling, do not press too hard on the drill, the feed should be slow and smooth.

When drilling metal, the sharpness of the drill is very important, while the drill becomes dull very quickly. The rate of blunting of the drill depends in particular on revolutions, feed force, cooling and other factors, however, no matter how hard you try, if a non-aluminum alloy is being drilled, the drill's operating time to unsatisfactory performance is measured in minutes.

Before drilling, it is necessary to mark the hole by punching it. To do this, you need to install the tip of the center punch (or dowel) in the intended center of the hole and hit it with a hammer. Piercing is necessary to prevent slipping of the drill at the first moment of drilling. If the core mark is not large enough to hold a large diameter drill, then first widen the hole with a small diameter drill.

To create the best drilling conditions, it is advisable to dip the tip of the drill in machine oil or drop it into the place of punching. The oil in the drilling zone contributes to better cooling of the drill and facilitates metal cutting. A drill drilled with oil is less blunt, requires less sharpening, and lasts longer. A special emulsion, soapy water, kerosene are also used as a coolant. According to some craftsmen, lard is a good lubricant and coolant. Before drilling, a rotating drill is immersed in a piece of fat, which melts during drilling and has a lubricating and cooling effect. But still the simplest and most convenient remedy is soapy water. It does not stain, and there is soap in every home. It is enough to drop it once at the beginning of drilling and in the process. You can periodically dip the drill in a soapy solution.

When through drilling with a high feed, a burr (burr) is formed at the exit of the hole, for which the drill clings to its side cutters. As a result, a sharp blocking of the drill and its fracture or chipping off of the cutter can occur, and even at this moment the drill becomes particularly intensely blunt. Such stops also have a negative effect on the state of the drill. To avoid the formation of burrs, you need to finish drilling holes in metal with a low feed. It is also advisable to place a wooden block under the drilled part, which prevents the formation of a burr. The bar and the workpiece must be tightly pressed against each other. For greater effect, you can put not a wooden block, but a plate of the same or less hard metal, which should be tightly pressed to the exit point of the drill.

Most often, it is necessary to drill steel, but it is often necessary to drill other metals, which have their own drilling characteristics. Aluminum, for example, envelops the drill, making it difficult for it to penetrate deep and widening the resulting hole. If you want to drill a precise hole in aluminum (for example, for a thread), you must always apply coolant and remove the drill from the hole more often to clean it. Ordinary gray cast iron is relatively easy to drill and does not require coolant or lubrication. But drilling in cast iron can bring surprises. There are ductile gray cast irons that need to be drilled with a carbide drill bit. White cast iron, the main structural component of which is cementite, is very hard, it requires a high-strength drill.

Large diameter holes should be drilled in stages. First you need to drill the part with a thin drill, then drill the hole to a larger diameter. For example, a hole with a diameter of 12 mm is best drilled in two or three steps - sequentially with 5, 10 and 12 mm drills.

Blunt drills need to be sharpened in a timely manner. It is better to do this with a sharpening tool, but you can do without it. In this case, you need to pay attention to the symmetry of the tip of the drill. If the sharpened edges do not meet strictly in the center, the hole drilled with such a drill will have a larger diameter, since one cutting edge will be longer than the other. The standard point angle (the angle between the cutting edges) is 118°. For drilling aluminum, an angle of 130-140 ° is considered optimal, soft bronze and red copper 125-130 °. However, all these metals can be drilled with a standard angle drill. Read more about drill sharpening.

When drilling, it is necessary to maintain the verticality of the drill relative to the metal surface (if it is not required to drill an inclined hole). When making holes in thin sheets, this requirement is not as relevant as for thick-walled or hollow parts. Drilling pipes, for example, often leads to the fact that the inlet and outlet holes are offset relative to each other - the more, the larger the diameter of the pipe. It is quite difficult to maintain the perpendicularity of the drill by eye, so you can use home-made or purchased drilling jigs or guides that ensure the perpendicularity of the drill.

Conductors are also needed for drilling two or more holes in mating parts. The best way to ensure the holes match is to drill them as an assembly. When drilling rivet holes, complete drilling is a must. Having drilled the first hole, you can use it to connect the parts with a bolt so that you can drill the remaining holes without fear that the parts will move relative to each other. If it is impossible or inconvenient to drill mating assembly parts, then a jig or guide must be used. You should know that no matter how accurately the mating holes are marked and punched, they will still not match absolutely exactly, since when drilling even a punched hole, the drill will go a little to the side.

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